Search results for: sludge reuse

Authors: Petros Gkotsis, Anastasios Zouboulis, Manasis Mitrakas, Dimitrios Zamboulis, E. Peleka

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The most serious drawback in wastewater treatment using membrane bioreactors (MBRs) is membrane fouling which gradually leads to membrane permeability decrease and efficiency deterioration. This work is part of a research project that aims to develop an integrated methodology for membrane fouling control, using specific chemicals which will enhance the coagulation and flocculation of compounds responsible for fouling, hence reducing biofilm formation on the membrane surface and limiting the fouling rate acting as a pre-treatment step. For this purpose, a pilot-scale plant with fully automatic operation achieved by means of programmable logic controller (PLC) has been constructed and tested. The experimental set-up consists of four units: wastewater feed unit, bioreactor, membrane (side-stream) filtration unit and permeate collection unit. Synthetic wastewater was fed as the substrate for the activated sludge. The dissolved oxygen (DO) concentration of the aerobic tank was maintained in the range of 2-3 mg/L during the entire operation by using an aerator below the membrane module. The membranes were operated at a flux of 18 LMH while membrane relaxation steps of 1 min were performed every 10 min. Both commercial and composite coagulants are added in different concentrations in the pilot-scale plant and their effect on the overall performance of the ΜΒR system is presented. Membrane fouling was assessed in terms of TMP, membrane permeability, sludge filterability tests, total resistance and the unified modified fouling index (UMFI). Preliminary tests showed that particular attention should be paid to the addition of the coagulant solution, indicating that pipe flocculation effectively increases hydraulic retention time and leads to voluminous sludge flocs. The most serious drawback in wastewater treatment using MBRs is membrane fouling, which gradually leads to membrane permeability decrease and efficiency deterioration. This results in increased treatment cost, due to high energy consumption and the need for frequent membrane cleaning and replacement. Due to the widespread application of MBR technology over the past few years, it becomes clear that the development of a methodology to mitigate membrane fouling is of paramount importance. The present work aims to develop an integrated technique for membrane fouling control in MBR systems and, thus, contribute to sustainable wastewater treatment.

Keywords: coagulation, membrane bioreactor, membrane fouling, pilot plant

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Authors: Passkorn Khanthongthip, John T. Novak

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Many studies have been reported that the nZVI and MgO NPs were often found in waste activated sludge (WAS). However, little is known about the impact of those NPs on WAS stabilization. The aims of this study were to investigate the effects of both NPs on WAS anaerobic digestion for methane production and to examine the change of metanogenic population under those different environments using qPCR. Four dosages (2, 50, 100, and 200 mg/g-TSS) of MgO NPs were added to four different bottles containing WAS to investigate the impact of MgO NPs on methane production during WAS anaerobic digestion. The effects of nZVI on methane production during WAS anaerobic digestion were also conducted in another four bottles using the same methods described above except that the MgO NPs were replaced by nZVI. A bottle of WAS anaerobic digestion without nanoparticles addition was also operated to serve as a control. It was found that the relative amounts, compared to the control system, of methane production in each WAS anaerobic digestion bottle adding 2, 50, 100, 200 mg/gTSS MgO NPs were 98, 62, 28, and 14 %, respectively. This suggests that higher MgO NPs resulted in lower methane production. The data of batch test for the effects of corresponding released Mg2+ indicated that 50 mg/gTSS MgO NPs or higher could inhibit methane production at least 25%. Moreover, the volatile fatty acid (VFA) concentration was 328, 384, 928, 3,684, and 7,848 mg/L for the control and four WAS anaerobic digestion bottles with 2, 50, 100, 200 mg/gTSS MgO NPs addition, respectively. Higher VFA concentration could reduce pH and subsequently decrease methanogen growth, resulting in lower methane production. The relative numbers of total gene copies of methanogens analyzed from samples taken from WAS anaerobic digestion bottles were approximately 99, 68, 38, and 24 % of control for the addition of 2, 50, 100, and 200 mg/gTSS, respectively. Obviously, the more MgO NPs appeared in sludge anaerobic digestion system, the less methanogens remained. In contrast, the relative amount of methane production found in another four WAS anaerobic digestion bottles adding 2, 50, 100, and 200 mg/gTSS nZVI were 102, 128, 112, and 104 % of the control, respectively. The measurement of methanogenic population indicated that the relative content of methanogen gene copies were 101, 132, 120, and 112 % of those found in control, respectively. Additionally, the cumulative VFA was 320, 234, 308, and 330 mg/L, respectively. This reveals that nZVI addition could assist to increase methanogenic population. Higher amount of methanogen accelerated VFA degradation for greater methane production, resulting in lower VFA accumulation in digesters. Moreover, the data for effects of corresponding released Fe2+ conducted by batch tests suggest that the addition of approximately 50 mg/gTSS nZVI increased methane production by 20%. In conclusion, the presence of MgO NPs appeared to diminish the methane production during WAS anaerobic digestion. Higher MgO NPs dosages resulted in more inhibition on methane production. In contrast, nZVI addition promoted the amount of methanogenic population which facilitated methane production.

Keywords: magnesium oxide nanoparticles, methane production, methanogenic population, nano zerovalent iron

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Authors: Ayda Maadani Mallak, Amir lakzian, Elham Khodaverdi, Gholam Hossein Haghnia

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The use of pharmaceuticals and personal care products such as antibiotics and antibacterials has been increased in recent years. Since the major part of consumed compounds remains unchanged in the wastewater treatment plant, they will easily find their way into the human food chain following the land use of sewage sludge (SS). Biological treatment of SS is one the most effective methods for expunging contaminants. White rot fungi, due to their ligninolytic enzymes, are extensively used to degrade organic compounds. Among all three different morphological forms and growth patterns of filamentous fungi (mycelia, clumps, and pellets), fungal pellet formation has been the subject of interest in industrial bioprocesses. Therefore this study was aimed to investigate the uptake of tetracycline (TC) and triclosan (TCS) by radish plant (Raphanus sativus) from soil amended with untreated and pretreated SS by P. ostreatus fungal pellets under greenhouse conditions. The experimental soil was amended with 1) Contaminated SS with TC at a concentration of 100 mgkg-1 and pretreated by fungal pellets, 2) Contaminated SS with TC at 100 mgkg-1 and untreated with fungal pellets, 3) Contaminated SS with TCS at a concentration of 50 mgkg-1 and pretreated by fungal pellets, 4) contaminated SS with TCS at 50 mgkg-1 and untreated with fungal pellets. An uncontaminated and untreated SS-amended soil also was considered as control treatment. An AB SCIEX 3200 QTRAP LC-MS/MS system was used in order to analyze the concentration of TC and TCS in plant tissues and soil medium. Results of this study revealed that the presence of TC and TCS in SS-amended soil decreased the radish biomass significantly. The reduction effect of TCS on dry biomass of shoot and root was 39 and 45% compared to controls, whereas for TC, the reduction percentage for shoot and root was 27 and 40.6%, respectively. However, fungal treatment of SS by P. ostreatus pellets reduced the negative effect of both compounds on plant biomass remarkably, as no significant difference was observed compared to control treatments. Pretreatment of SS with P. ostreatus also caused a significant reduction in translocation factor (concentration in shoot/root), especially for TC compound up to 32.3%, whereas this reduction for TCS was less (8%) compared to untreated SS. Generally, the results of this study confirmed the positive effect of using fungal pellets in SS amendment to decrease TC and TCS uptake by radish plants. In conclusion, P. ostreatus fungal pellets might provide future insights into bioaugmentation to remove antibiotics from environmental matrices.

Keywords: antibiotic, fungal pellet, sewage sludge, white-rot fungi

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Authors: Pinzón Uribe Luis Felipe, Chávez Porras Álvaro, Ruge Castellanos Liliana Constanza

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According to global data, solid waste management of has low economic investment for its management in underdeveloped countries; being the main factor the advanced technologies acknowledge for proper operation and at the same time the technical development. Has been evidenced that communities have a distorted perception of the role and legalized final destinations for waste or "Landfill" places specific management; influenced primarily by their physical characteristics and the information that the media provide of these, as well as their wrong association with "open dumps". One of the major inconveniences in these landfills is the leachate sludge management from treatment plants; as this exhibit a composition highly contaminating (physical, chemical and biological) for the natural environment due to improper handling and disposal. This is the case Landfill Doña Juana (RSDJ), Bogotá, Colombia, considered among the largest in South America; where management problems have persisted for decades, since its creation being definitive on the concept that society has acquired about this form of waste disposal and improper leachate handling. Within this research process for treating phytoremediation alternatives were determined by using plants that are able to degrade heavy metals contained in these; allowing the resulting sludge to be used as a seal in the final landfill cover; within a restoration process, providing option to solve the landscape contamination problem, as well as in the communities perception and conflicts that generates landfill. For the project chemical assays were performed in sludge leachate that allowed the characterization of metals such as chromium (Cr), lead (Pb), arsenic (As) and mercury (Hg), in order to meet the amount in the biosolids regard to the provisions of the USEPA 40 CFR 503. The evaluations showed concentrations of 102.2 mg / kg of Cr, 0.49 mg / kg Pb, 0.390 mg / kg of As and 0.104 mg / kg of Hg; being lower than of the standards. A literature review on native plant species suitable for an alternative process of phytoremediation, these metals degradation capable was developed. Concluding that among them, Vetiveria zizanioides, Eichhornia crassipes and Limnobium laevigatum, for their hiperacumulativas in their leaves, stems and roots characteristics may allow these toxic elements reduction of in the environment, improving the outlook for disposal.

Keywords: health, filling slurry of leachate, heavy metals, phytoremediation

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Authors: Nor-Edine Abriak, Ilyas Ennahal, Abdeljalil Zri, Mahfoud Benzerzour

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Nord Pas de Calais is one of the French regions that records a large volume of dredged sediment in harbors and waterways. To ensure navigation within ports and waterways, harbor and river managers are forced to find solutions to remove sediment that contamination levels exceed levels established by regulations. Therefore, this non- submersible sediment must be managed on land and will be subject to the waste regulation. In this paper, some examples of concrete achievements and experiments of reusing dredged sediment in civil engineering and sector will be illustrated. These achievements are alternative solutions to sediment landfilling and guarantee the reuse of this material in a logic of circular economy and ecological transition. It permits to preserve the natural resources increasingly scarce and resolve issues related to the accumulation of sediments in the harbor basins, rivers, dams, and lakes, etc. Examples of beneficial use of dredged material illustrated in this paper are the result of different projects reusing harbor and waterways sediments in several applications. These projects were funded under the national SEDIMATERIAUX approach. Thus the technical and environmental feasibility of the reuse of dredged sediment is demonstrated and verified; the dredged sediment reusing would meet multiple challenges of sustainable development in relation to environmental, economic, social and societal.

Keywords: circular economy, sediment, SEDIMATERIAUX, waterways

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Authors: Abdelkader T. Ahmed

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Greywater is any wastewater draining from a household including kitchen sinks and bathroom tubs, except toilet wastes. Although this used water may contain grease, food particles, hair, and any number of other impurities, it may still be suitable for reuse after treatment. Greywater reusing serves two purposes including reduction the amount of freshwater needed to supply a household, and reduction the amount of wastewater entering sewer systems. This study aims to investigate and design a simple and cheap unit to treat the greywater in household via using ceramic membranes and reuse it in supplying water for toilet flushing. The study include an experimental program for manufacturing several tablet ceramic membranes from clay and sawdust with three different mixtures. The productivity and efficiency of these ceramic membranes were investigated by chemical and physical tests for greywater before and after filtration through these membranes. Then a treatment unit from this ceramic membrane was designed based on the experimental results of lab tests. Results showed that increase sawdust percent with the mixture increase the flow rate and productivity of treated water but decrease in the same time the water quality. The efficiency of the new ceramic membrane reached 95%. The treatment unit save 0.3 m3/day water for toilet flushing without need to consume them from the fresh water supply network.

Keywords: ceramic membranes, filtration, greywater, wastewater treatment

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Authors: Ann Mariya Jose, Ashfina T.

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Construction and demolition waste is one of the rising concerns globally due to the amount of waste generated annually, the area taken up by landfills, and the adverse environmental impacts that follow. One of the primary causes of the rise in construction and demolition waste is a lack of facilities and knowledge for incorporating recycled materials into new construction. Bricks are a conventional material that has been used for construction for centuries, and Autoclave Aerated Concrete (AAC) blocks are a new emergent material in the market. This study evaluates the impact brick walls, and AAC block walls have on the environment using the tool One Click LCA, considering three End of Life (EoL) scenarios: the materials are landfilled, recycled, and reused in a new building. The final objective of the study is to evaluate the environmental impact caused by these two different walls on the environmental factors such as Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), Ozone Depletion Potential (ODP), and Photochemical Ozone Creation Potential (POCP). The findings revealed that the GWP caused by landfilling is 16 times higher in bricks and 22 times higher in AAC blocks when compared to the reuse of materials. The study recommends the effective use of AAC blocks in construction and reuse of the same to reduce the overall emissions to the environment.

Keywords: construction and demolition waste, environmental impact, life cycle impact assessment, material recycling

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Authors: Almaz Negash, Dessie Tibebe, Marye Mulugeta, Yezbie Kassa

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Large-scale textile industries use large amounts of toxic chemicals, which are very hazardous to human health and environmental sustainability. In this study, the removal of various dyes from effluents of textile industries using the electrocoagulation process was investigated. The studied dyes were Reactive Red 120 (RR-120), Basic Blue 3 (BB-3), and Basic Red 46 (BR-46), which were found in samples collected from effluents of three major textile factories in the Amhara region, Ethiopia. For maximum removal, the dye BB-3 required an acidic pH 3, RR120 basic pH 11, while BR-46 neutral pH 7 conditions. BB-3 required a longer treatment time of 80 min than BR46 and RR-120, which required 30 and 40 min, respectively. The best removal efficiency of 99.5%, 93.5%, and 96.3% was achieved for BR-46, BB-3, and RR-120, respectively, from synthetic wastewater containing 10 mg L1of each dye at an applied potential of 10 V. The method was applied to real textile wastewaters and 73.0 to 99.5% removal of the dyes was achieved, Indicating Electrocoagulation can be used as a simple, and reliable method for the treatment of real wastewater from textile industries. It is used as a potentially viable and inexpensive tool for the treatment of textile dyes. Analysis of the electrochemically generated sludge by X-ray Diffraction, Scanning Electron Microscope, and Fourier Transform Infrared Spectroscopy revealed the expected crystalline aluminum oxides (bayerite (Al(OH)3 diaspore (AlO(OH)) found in the sludge. The amorphous phase was also found in the floc. Textile industry owners should be aware of the impact of the discharge of effluents on the Ecosystem and should use the investigated electrocoagulation method for effluent treatment before discharging into the environment.

Keywords: electrocoagulation, aluminum electrodes, Basic Blue 3, Basic Red 46, Reactive Red 120, textile industry, wastewater

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Authors: L. Bouqbis, H.W. Koyro, M. C. Harrouni, S. Daoud, L. F. Z. Ainlhout, C. I. Kammann

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The application of biochar to soils is becoming more and more common. Its application which is generally reported to improve the physical, chemical, and biological properties of soils, has an indirect effect on soil health and increased crop yields. However, many of the previous results are highly variable and dependent mainly on the initial soil properties, biochar characteristics, and production conditions. In this study, two biochars which are biochar II (BC II) derived from a blend of paper sludge and wheat husks and biochar 005 (BC 005) derived from sewage sludge with a KCl additive, are used, and the physical and chemical properties of BC II are characterized. To determine the potential impact of salt stress and toxic and volatile substances, the second part of this study focused on the effect biochars have on germination of salad (Lactuca sativa L.), barley (Hordeum vulgare), and cress (Lepidium sativum) respectively. Our results indicate that Biochar II showed some unique properties compared to the soil, such as high EC, high content of K, Na, Mg, and low content of heavy metals. Concerning salad and barley germination test, no negative effect of BC II and BC 005 was observed. However, a negative effect of BC 005 at 8% level was revealed. The test of the effect of volatile substances on germination of cress revealed a positive effect of BC II, while a negative effect was observed for BC 005. Moreover, the water holding capacities of biochar-sand mixtures increased with increasing biochar application. Collectively, BC II could be safely used for agriculture and could provide the potential for a better plant growth.

Keywords: biochar, phytotoxic tests, seedlings growth, water holding capacity

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Authors: Lidia Lombardi

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Waste management in Europe and North America is evolving towards sustainable materials management, intended as a systemic approach to using and reusing materials more productively over their entire life cycles. Various waste management strategies are prioritized and ranked from the most to the least environmentally preferred, placing emphasis on reducing, reusing, and recycling as key to sustainable materials management. However, non-recyclable materials must also be appropriately addressed, and waste-to-energy (WtE) offers a solution to manage them, especially when a WtE plant is integrated within a complex system of waste and wastewater treatment plants and potential users of the output flows. To evaluate the environmental effects of such system integration, Life Cycle Assessment (LCA) is a helpful and powerful tool. LCA has been largely applied to the waste management sector, dating back to the late 1990s, producing a large number of theoretical studies and applications to the real world as support to waste management planning. However, LCA still has a fundamental role in helping the development of waste management systems supporting decisions. Thus, LCA was applied to evaluate the environmental performances of a Municipal Solid Waste (MSW) management system, with improved separate material collection and recycling and an integrated network of treatment plants including WtE, anaerobic digestion (AD) and also wastewater treatment plant (WWTP), for a reference study case area. The proposed system was compared to the actual situation, characterized by poor recycling, large landfilling and absence of WtE. The LCA results showed that the increased recycling significantly increases the environmental performances, but there is still room for improvement through the introduction of energy recovery (especially by WtE) and through its use within the system, for instance, by feeding the heat to the AD, to sludge recovery processes and supporting the water reuse practice. WtE offers a solution to manage non-recyclable MSW and allows saving important resources (such as landfill volumes and non-renewable energy), reducing the contribution to global warming, and providing an essential contribution to fulfill the goals of really sustainable waste management.

Keywords: anaerobic digestion, life cycle assessment, waste-to-energy, municipal solid waste

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Authors: R. K. D. G. Kaluarachchi

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The generation of solid waste and its effective management are debated topics in Sri Lanka as well as in the global environment. It was estimated that the most of the waste generated in global was originated from construction and demolition of buildings. Thus, the proportion of construction waste in solid waste generation cannot be underestimated. The construction waste, which is the by-product generated and removed from work sites is collected in direct and indirect processes. Hence, the objectives of this research are to identify the proportion of construction waste which can be reused and identify the methods to reduce the waste generation without reducing the quality of the process. A 6-storey building construction site was selected for this research. The site was divided into six zones depending on the process. Ten waste materials were identified by considering the adverse effects on safety and health of people and the economic value of them. The generated construction waste in each zone was recorded per week for a period of five months. The data revealed that sand, cement, wood used for form work and rusted steel rods were the generated waste which has higher economic value in all zones. Structured interviews were conducted to gather information on how the materials are categorized as waste and the capability of reducing, reusing and recycling the waste. It was identified that waste is generated in following processes; ineffective storage of material for a longer time and improper handling of material during the work process. Further, the alteration of scheduled activities of construction work also yielded more waste. Finally, a proper management of construction waste is suggested to reduce and reuse waste.

Keywords: construction-waste, effective management, reduce, reuse

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Authors: Hanen Filali, Mohamed Hachicha

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Treated grey water (TGW) reuse emerged as an alternative resource to meet the growing demand for water for agricultural irrigation and reduce the pressure on limited existing fresh water. However, this reuse needs adapted management in order to avoid environmental and health risks. In this work, the treatment of grey water (GW) was studied from a cyclic treatment system that we designed and implemented in the greenhouse of National Research Institute for Rural Engineering, Water and Forests (INRGREF). This system is composed of three levels for treatment (TGW 1, TGW 2, and TGW 3). Each level includes a sandy soil box. The use of grey water was moderated depending on the chemical and microbiological quality obtained. Different samples of soils and treated grey water were performed and analyzed for 14 irrigation cycles. TGW through cyclic treatment showed physicochemical parameters like pH, electrical conductivity (EC), chemical oxygen demand (COD), biological oxygen demand (BOD5) in the range of 7,35-7,91, 1,69-5,03 dS/m, 102,6-54,2 mgO2/l, and 31,33-15,74 mgO2/l, respectively. Results showed a reduction in the pollutant load with a significant effect on the three treatment levels; however, an increase in salinity was observed during all irrigation cycles. Microbiological results showed good grey water treatment with low health risk on irrigated soil. Treated water quality was below permissible Tunisian standards (NT106.03), and treated water is suitable for non-potable options.

Keywords: treated grey water, irrigation, cyclic treatment, soils, physico-chemical parameters, microbiological parameters

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Authors: Oluyemi O. Awolusi, Abimbola M. Enitan, Sheena Kumari, Faizal Bux

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Nitrification is essential to biological processes designed to remove ammonia and/or total nitrogen. It removes the excess nitrogenous compound in wastewater which could be very toxic to the aquatic fauna or cause a serious imbalance of such aquatic ecosystem. Efficient nitrification is linked to an in-depth knowledge of the structure and dynamics of the nitrifying community structure within the wastewater treatment systems. In this study, molecular technique was employed for characterizing the microbial structure of activated sludge [ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB)] in a municipal wastewater treatment with intention of linking it to the plant efficiency. PCR-based phylogenetic analysis was also carried out for. The average operating and environmental parameters, as well as specific nitrification rate of a plant, was investigated during the study. During the investigation, the average temperature was 23±1.5oC. Other operational parameters such as mixed liquor suspended solids and chemical oxygen demand inversely correlated with ammonia removal. The dissolved oxygen level in the plant was constantly lower than the optimum (between 0.24 and 1.267 mg/l) during this study. The plant was treating wastewater with the influent ammonia concentration of 31.69 and 24.47 mg/l. The influent flow rates (ML/day) was 96.81 during the period. The dominant nitrifiers include: Nitrosomonas spp. Nitrobacter spp. and Nitrospira spp. The AOB had a correlation with nitrification efficiency and temperature. This study shows that the specific ammonia oxidizing rate and the specific nitrate formation rates can serve as a good indicator of the plant overall nitrification performance.

Keywords: Ammonia monooxygenase α-subunit gene, amoA, ammonia-oxidizing bacteria, AOB, nitrite-oxidizing bacteria, NOB, specific nitrification rate

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Authors: Pedro M. Velasco, Cecilia C. Alday, Oscar C. Avello, Ximena T. Faundez, Luis M. Velasco

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Anaerobic digestion (AD) plants of food waste (FW) produced by agro-industry, have been widely developed from last decade to nowadays, because of the advantages over aerobic active sludge systems. Despite several bioreactor configurations and operation modes have been successfully improved and implemented at industrial scale in a wide range of applications, effluent behavior, after AD, does not commonly meet requirements for direct disposal into the environment without further treatments. In addition, literature has rarely shown AD of food waste at psychrophilic range. This temperature range may be of interest for making AD plant operation easier and increasing the stability of digestion. In spite of literature shows several methods for post-treatment, such as the use of microalgae, these have not been cultivated on effluents from AD at psychrophilic range. Hence, with the aim of showing the potential use of AD of FW at the psychrophilic range (25ºC) and the viability of microalgae post-treatment, single batch reactors have been used for methane potential tests at laboratory scale. Afterwards, digestates, derived from this AD of FW sludge, were diluted with fresh water at different ratios (1:0, 1:1; 1:4) and used as culture media for photoautotrophic microalgae. Several parameters, such as pH, biogas production, and chemical oxygen demand, were measured periodically over several months. Results show that methane potential is 150 ml g-1 per volatile solid with up to 57.7 % of methane content. Moreover, microalgae has been successfully cultivated on all tested effluents and in case of 1:1 and 1:4 rates, the resulting effluents meet the quality levels required for irrigation water.

Keywords: anaerobic digestion, biogas, food waste, microalgae, psychrophilic range

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Authors: Q. Rzina, M. Lahrouni, S. Rida, N. Saadaoui, Y. Almossaid, K. Oufdou, K. Fares

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Many organic solid wastes are produced in the world. Poultry manure (PM), municipal organic wastes (MOW) and sugar beet lime sludge (LS) are produced in large quantities in Morocco. The co-composting of these organic wastes was investigated. The recycling and the valorization of such wastes is environmentally and economically beneficial especially for PM which is known source of bacterial pathogens. The aerobic biodegradation process was carried out by using three windrows of variable compositions: C1 prepared without LS (only MOW were composted with PM), C2 prepared from MOW plus PM and10% LS; and the last one C3 from MOW plus PM and 20% LS. The main process physico-chemical parameters (temperature, pH, humidity and C/N) and microbiological populations (mesophilic and thermophilic flora, total coliform, fecal coliform, Streptococci, Staphylococcus aureus and mesophilic fungi) were monitored over three months to ascertain the compost maturity and to ensure the compost hygienic aspect. The final products were characterized by their relatively high organic matter content, and low C/N ratio of 10.6-10.9. The organic matter degradation was reached approximately 59% for C2 and C3. In addition, the monitoring of the microbial population showed that the produced composts are mature and hygienic. The agronomic valorization of the final composts was tested on radish plant with tree level of composts and poultry manure without composting. The primary results of field trial showed a growth of radish plant biomass and root development without any phytotoxicity detected which reflects the quality of the composts produced. As for poultry manure it allowed to have a better results than other composts because of its readily available nitrogen.

Keywords: compost, municipal organic wastes, poultry manure, radish crop, sugar beet lime sludge

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Authors: Riad Benelmir, Muhammad Shoaib Ahmed Khan

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The socio-economic importance of the olive oil production is significant in the Mediterranean region, both in terms of wealth and tradition. However, the extraction of olive oil generates huge quantities of wastes that may have a great impact on land and water environment because of their high phytotoxicity. Especially olive mill wastewater (OMWW) is one of the major environmental pollutants in olive oil industry. This work projects to design a smart and sustainable integrated thermochemical catalytic processes of residues from olive mills by hydrothermal carbonization (HTC) of olive mill wastewater (OMWW) and fast pyrolysis of olive mill wastewater sludge (OMWS). The byproducts resulting from OMWW-HTC treatment are a solid phase enriched in carbon, called biochar and a liquid phase (residual water with less dissolved organic and phenolic compounds). HTC biochar can be tested as a fuel in combustion systems and will also be utilized in high-value applications, such as soil bio-fertilizer and as catalyst or/and catalyst support. The HTC residual water is characterized, treated and used in soil irrigation since the organic and the toxic compounds will be reduced under the permitted limits. This project’s concept includes also the conversion of OMWS to a green diesel through a catalytic pyrolysis process. The green diesel is then used as biofuel in an internal combustion engine (IC-Engine) for automotive application to be used for clean transportation. In this work, a theoretical study is considered for the use of heat from the pyrolysis non-condensable gases in a sorption-refrigeration machine for pyrolysis gases cooling and condensation of bio-oil vapors.

Keywords: biomass, olive oil extraction, adsorption cooling, pyrolisis

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Authors: Daniela Rimnacova, Maryna Vorokhta, Martina Svabova

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CO₂ adsorption capacity of several materials - waste (power fly ash, slag, carbonized sewage sludge), rocks (Czech Silurian shale, black coal), and carbon (synthesized carbon, activated carbon as a reference material) - were measured on dry samples using a unique hand-made manometric sorption apparatus at a temperature of 45 °C and pressures of up to 7 MPa. The main aim was finding utilization of the waste materials and rocks for removal of the air or water pollutants caused by anthropogenic activities, as well as for the carbon dioxide storage. The equilibrium amount of the adsorbate depends on temperature, gas saturation pressure, porosity, surface area and volume of pores, and last but not least, on the composition of the adsorbents. Given experimental conditions can simulate in-situ situations in the rock bed and can be achieved just by a high-pressure apparatus. The CO₂ excess adsorption capacities ranged from 0.018 mmol/g (ash) to 13.55 mmol/g (synthesized carbon). The synthetized carbon had the highest adsorption capacity among all studied materials as well as the highest price. This material is usually used for the adsorption of specific pollutants. The excess adsorption capacity of activated carbon was 9.19 mmol/g. It is used for water and air cleaning. Ash can be used for chemisorption onto ash particle surfaces or capture of special pollutants. Shale is a potential material for enhanced gas recovery or CO₂ sequestration in-situ. Slag is a potential material for capture of gases with a possibility of the underground gas storage after the adsorption process. The carbonized sewage sludge is quite a good adsorbent for the removal and capture of pollutants, as well as shales or black coal which show an interesting relationship between the price and adsorption capacity.

Keywords: adsorption, CO₂, high pressure, porous materials

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Authors: A. Laksanayothin, W. Ariyawong

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Mae Moh Lignite Mine is the largest open-pit mine in Thailand. The mine serves coal to the power plant about 16 million tons per year. This amount of coal can produce electricity accounting for about 10% of Nation’s electric power generation. The mining area of Mae Moh Mine is about 28 km2. At present, the deepest area of the pit is about 280 m from ground level (+40 m. MSL) and in the future the depth of the pit can reach 520 m from ground level (-200 m.MSL). As the size of the pit is quite large, the stability of the pit is seriously important. Furthermore, the preliminary drilling and extended drilling in year 1989-1996 had found high pressure aquifer under the pit. As a result, the pressure of the underground water has to be released in order to control mine pit stability. The study by the consulting experts later found that 3-5 million m3 per year of the underground water is needed to be de-watered for the safety of mining. However, the quality of this discharged water should meet the standard. Therefore, the ground water treatment facility has been implemented, aiming to reduce the amount of naturally contaminated Arsenic (As) in discharged water lower than the standard limit of 10 ppb. The treatment system consists of coagulation and filtration process. The main components include rapid mixing tanks, slow mixing tanks, sedimentation tank, thickener tank and sludge drying bed. The treatment process uses 40% FeCl3 as a coagulant. The FeCl3 will adsorb with As(V), forming floc particles and separating from the water as precipitate. After that, the sludge is dried in the sand bed and then be disposed in the secured land fill. Since 2011, the treatment plant of 12,000 m3/day has been efficiently operated. The average removal efficiency of the process is about 95%.

Keywords: arsenic, coagulant, ferric chloride, groundwater, lignite, coal mine

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Authors: Swati Tomar, Sunil Kumar Gupta

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Anammox is a novel and promising technology that has changed the traditional concept of biological nitrogen removal. The process facilitates direct oxidation of ammonical nitrogen under anaerobic conditions with nitrite as an electron acceptor without the addition of external carbon sources. The present study investigated the feasibility of anammox hybrid reactor (AHR) combining the dual advantages of suspended and attached growth media for biodegradation of ammonical nitrogen in wastewater. The experimental unit consisted of 4 nos. of 5L capacity AHR inoculated with mixed seed culture containing anoxic and activated sludge (1:1). The process was established by feeding the reactors with synthetic wastewater containing NH4-H and NO2-N in the ratio 1:1 at HRT (hydraulic retention time) of 1 day. The reactors were gradually acclimated to higher ammonium concentration till it attained pseudo steady state removal at a total nitrogen concentration of 1200 mg/l. During this period, the performance of the AHR was monitored at twelve different HRTs varying from 0.25-3.0 d with increasing NLR from 0.4 to 4.8 kg N/m3d. AHR demonstrated significantly higher nitrogen removal (95.1%) at optimal HRT of 1 day. Filter media in AHR contributed an additional 27.2% ammonium removal in addition to 72% reduction in the sludge washout rate. This may be attributed to the functional mechanism of filter media which acts as a mechanical sieve and reduces the sludge washout rate many folds. This enhances the biomass retention capacity of the reactor by 25%, which is the key parameter for successful operation of high rate bioreactors. The effluent nitrate concentration, which is one of the bottlenecks of anammox process was also minimised significantly (42.3-52.3 mg/L). Process kinetics was evaluated using first order and Grau-second order models. The first-order substrate removal rate constant was found as 13.0 d-1. Model validation revealed that Grau second order model was more precise and predicted effluent nitrogen concentration with least error (1.84±10%). A new mathematical model based on mass balance was developed to predict N2 gas in AHR. The mass balance model derived from total nitrogen dictated significantly higher correlation (R2=0.986) and predicted N2 gas with least error of precision (0.12±8.49%). SEM study of biomass indicated the presence of the heterogeneous population of cocci and rod shaped bacteria of average diameter varying from 1.2-1.5 mm. Owing to enhanced NRE coupled with meagre production of effluent nitrate and its ability to retain high biomass, AHR proved to be the most competitive reactor configuration for dealing with nitrogen laden wastewater.

Keywords: anammox, filter media, kinetics, nitrogen removal

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Authors: Wa`d Odeh, Alon Tal, Alfred Abed Rabbo, Nader Al Khatib, Shai Arnon

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The presence of endocrine disrupting compounds (EDCs) in raw sewage and effluents from wastewater treatment plants (WWTPs) has been increasingly studied in the last few decades. Higher risks are said to characterize situations where raw sewage streams are found to be flowing, or where partial and inadequate wastewater treatment exists. Such conditions are prevalent in the West Bank area of Palestine. To our knowledge, no previous data concerning the occurrence and fate of EDCs in the aquatic environment has ever been systematically evaluated in the region. Hence, the main objective of this study was to identify the occurrence and concentrations of major EDCs in raw sewage, wastewater effluents produced by treatment plants and in the receiving environments, including streams and groundwater in the West Bank, Palestine. Water samples were collected and analyzed for four times during the years of 2013 and 2014. Two large-scale conventional activated sludge WWTPs, two wastewater watercourses, one naturally perennial stream, and five groundwater locations close to wastewater sources were sampled and analyzed by GC/MS following EPA methods (525.2). Five EDCs (estriol, estrone, testosterone, bisphenol A, and octylphenol) were detected in trace concentrations (ng/l) in wastewater streams and at inputs to WWTPs. WWTPs were not able to achieve complete removal of all EDCs, and EDCs were still found in the effluents. In this regard, the most significant environmental estrogenic impact was due to estrone concentrations. Nevertheless, no EDCs were detected in groundwater. Yet, in order for effluents to be reused, significant improvement in treatment infrastructure should be a top priority for environmental managers in the region.

Keywords: endocrine disrupting compounds, raw sewage streams, conventional activated sludge WWTPs, WWTPs effluents

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Authors: Seyedomid Fatemi

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The walls of the building, as the main intermediary between the outside and the inside of the building, play an important role in controlling the environmental conditions and ensuring the comfort of the residents, thus reducing the heating and cooling loads. Therefore, the use of suitable materials is considered one of the simplest and most effective ways to reduce the heating and cooling loads of the building, which will also save energy. Therefore, in order to achieve the goal of the research "Ranking of optimal materials for building walls," optimal materials for building walls in a temperate and humid climate (case example: Sari city) from the perspective of embodied energy, waste of electricity and gas energy, cost and reuse been investigated to achieve sustainable architecture. In this regard, using information obtained from Sari Municipality, design components have been presented by experts using the Delphi method. Considering the criteria of experts' opinions (cost and reuse), the amount of embodied energy of the materials, as well as the amount of waste of electricity and gas of different materials of the walls, with the help of the AHP weighting technique and finally with the TOPSIS technique, the best type of materials in the order of 1- 3-D Panel 2-ICF-, 3-Cement block with pumice, 4-Wallcrete block, 5-Clay block, 6-Autoclaved Aerated Concrete (AAC), 7-Foam cement block, 8-Aquapanel and 9-Reinforced concrete wall for use in The walls of the buildings were proposed in Sari city.

Keywords: optimum materials, building walls, moderate and humid climate, sustainable architecture, AHP-TOPSIS technique

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Authors: Balgaisha Mukanova, Natalya Glazyrina, Sergey Glazyrin

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The formulated problem of optimization of the technological process of water treatment for thermal power plants is considered in this article. The problem is of multiparametric nature. To optimize the process, namely, reduce the amount of waste water, a new technology was developed to reuse such water. A mathematical model of the technology of wastewater reuse was developed. Optimization parameters were determined. The model consists of a material balance equation, an equation describing the kinetics of ion exchange for the non-equilibrium case and an equation for the ion exchange isotherm. The material balance equation includes a nonlinear term that depends on the kinetics of ion exchange. A direct problem of calculating the impurity concentration at the outlet of the water treatment plant was numerically solved. The direct problem was approximated by an implicit point-to-point computation difference scheme. The inverse problem was formulated as relates to determination of the parameters of the mathematical model of the water treatment plant operating in non-equilibrium conditions. The formulated inverse problem was solved. Following the results of calculation the time of start of the filter regeneration process was determined, as well as the period of regeneration process and the amount of regeneration and wash water. Multi-parameter optimization of water treatment process for thermal power plants allowed decreasing the amount of wastewater by 15%.

Keywords: direct problem, multiparametric optimization, optimization parameters, water treatment

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Authors: Dimitra C. Banti, Gesthimani Liona, Petros Samaras, Manasis Mitrakas

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Municipal and industrial wastewaters are often treated biologically, by the activated sludge process (ASP). The ASP not only requires large aeration and sedimentation tanks, but also generates large quantities of excess sludge. An alternative technology is the membrane bioreactor (MBR), which replaces two stages of the conventional ASP—clarification and settlement—with a single, integrated biotreatment and clarification step. The advantages offered by the MBR over conventional treatment include reduced footprint and sludge production through maintaining a high biomass concentration in the bioreactor. Notwithstanding these advantages, the widespread application of the MBR process is constrained by membrane fouling. Fouling leads to permeate flux decline, making more frequent membrane cleaning and replacement necessary and resulting to increased operating costs. In general, membrane fouling results from the interaction between the membrane material and the components in the activated sludge liquor. The latter includes substrate components, cells, cell debris and microbial metabolites, such as Extracellular Polymeric Substances (EPS) and Sludge Microbial Products (SMPs). The challenge for effective MBR operation is to minimize the rate of Transmembrane Pressure (TMP) increase. This can be achieved by several ways, one of which is the addition of specific additives, that enhance the coagulation and flocculation of compounds, which are responsible for fouling, hence reducing biofilm formation on the membrane surface and limiting the fouling rate. In this project the effectiveness of a non-commercial composite coagulant was studied as an agent for fouling control in a lab scale MBR system consisting in two aerated tanks. A flat sheet membrane module with 0.40 um pore size was submerged into the second tank. The system was fed by50 L/d of municipal wastewater collected from the effluent of the primary sedimentation basin. The TMP increase rate, which is directly related to fouling growth, was monitored by a PLC system. EPS, MLSS and MLVSS measurements were performed in samples of mixed liquor; in addition, influent and effluent samples were collected for the determination of physicochemical characteristics (COD, BOD5, NO3-N, NH4-N, Total N and PO4-P). The coagulant was added in concentrations 2, 5 and 10mg/L during a period of 2 weeks and the results were compared with the control system (without coagulant addition). EPS fractions were extracted by a three stages physical-thermal treatment allowing the identification of Soluble EPS (SEPS) or SMP, Loosely Bound EPS (LBEPS) and Tightly Bound EPS (TBEPS). Proteins and carbohydrates concentrations were measured in EPS fractions by the modified Lowry method and Dubois method, respectively. Addition of 2 mg/L coagulant concentration did not affect SEPS proteins in comparison with control process and their values varied between 32 to 38mg/g VSS. However a coagulant dosage of 5mg/L resulted in a slight increase of SEPS proteins at 35-40 mg/g VSS while 10mg/L coagulant further increased SEPS to 44-48mg/g VSS. Similar results were obtained for SEPS carbohydrates. Carbohydrates values without coagulant addition were similar to the corresponding values measured for 2mg/L coagulant; the addition of mg/L coagulant resulted to a slight increase of carbohydrates SEPS to 6-7mg/g VSS while a dose of 10 mg/L further increased carbohydrates content to 9-10mg/g VSS. Total LBEPS and TBEPS, consisted of proteins and carbohydrates of LBEPS and TBEPS respectively, presented similar variations by the addition of the coagulant. Total LBEPS at 2mg/L dose were almost equal to 17mg/g VSS, and their values increased to 22 and 29 mg/g VSS during the addition of 5 mg/L and 10 mg/L of coagulant respectively. Total TBEPS were almost 37 mg/g VSS at a coagulant dose of 2 mg/L and increased to 42 and 51 mg/g VSS at 5 mg/L and 10 mg/L doses, respectively. Therefore, it can be concluded that coagulant addition could potentially affect microorganisms activities, excreting EPS in greater amounts. Nevertheless, EPS increase, mainly SEPS increase, resulted to a higher membrane fouling rate, as justified by the corresponding TMP increase rate. However, the addition of the coagulant, although affected the EPS content in the reactor mixed liquor, did not change the filtration process: an effluent of high quality was produced, with COD values as low as 20-30 mg/L.

Keywords: extracellular polymeric substances, MBR, membrane fouling, EPS

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Authors: Swati Tomar, Sunil Kumar Gupta

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The start-up of anammox (anaerobic ammonium oxidation) process in hybrid reactor delineated four distinct phases i.e. cell lysis, lag phase, activity elevation and stationary phase. Cell lysis phase was marked by death and decay of heterotrophic denitrifiers resulting in breakdown of organic nitrogen into ammonium. Lag phase showed initiation of anammox activity with turnover of heterotrophic denitrifiers, which is evident from appearance of NO3-N in the effluent. In activity elevation phase, anammox became the dominant reaction, which can be attributed to consequent reduction of NH4-N into N2 with increased NO3-N in the effluent. Proper selection of mixed seed culture at influent NO2-/NH4+ ratio (1:1) and hydraulic retention time (HRT) of 1 day led to early startup of anammox within 70 days. Pseudo steady state removal efficiencies of NH4+ and NO2- were found as 94.3% and 96.4% respectively, at nitrogen loading rate (NLR) of 0.35 kg N/m3d at an HRT of 1 day. Analysis of the data indicated that attached growth system contributes an additional 11% increase in the ammonium removal and results in an average of 29% reduction in sludge washout rate. Mass balance study of nitrogen indicated that 74.1% of total input nitrogen is converted into N2 gas followed by 11.2% being utilized in biomass development. Scanning electron microscope (SEM) observation of the granular sludge clearly showed the presence of cocci and rod shaped microorganisms intermingled on the external surface of the granules. The average size of anammox granules (1.2-1.5 mm) with an average settling velocity of 45.6 m/h indicated a high degree of granulation resulting into formation of well compacted granules in the anammox process.

Keywords: anammox, hybrid reactor, startup, granulation, nitrogen removal, mixed seed culture

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Authors: Gor Muradyan

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The paper is about friction and wear, including mechanisms, modeling, characterization, measurement and testing case in Bangladesh. Bangladesh is a country under development, A lot of people live here, approximately 145 million. The territory of this country is very small. Therefore buildings are very close to each other. As the pipe lines are very old, and people get almost dirty water, there are a lot of ongoing projects under ADB. In those projects the contractors using HDD machines (Horizontal Directional Drilling ) and grundoburst. These machines are working underground. As ground in Bangladesh is very sludge, machine can't work relevant because of big friction in the soil. When drilling works are finished machine is pulling the pipe underground. Very often the pulling of the pipes becomes very complicated because of the friction. Therefore long section of the pipe laying can’t be done because of a big friction. In that case, additional problems rise, as well as additional work must be done. As we mentioned above it is not possible to do big section of the pipe laying because of big friction in the soil, Because of this it is coming out that contractors must do more joints, more pressure test. It is always connected with additional expenditure and losing time. This machine can pull in 75 mm to 500 mm pipes connected with the soil condition. Length is possible till 500m related how much friction it will had on the puller. As less as much it can pull. Another machine grundoburst is not working at this soil condition at all. The machine is working with air compressor. This machine are using for the smaller diameter pipes, 20 mm to 63 mm. Most of the cases these machines are being used for the installing of the house connection pipes, for making service connection. To make a friction less contractors using bigger pulling had then the pipe. It is taking down the friction, But the problem of this machine is that it can't work at sludge. Because of mentioned reasons the friction has a big mining during this kind of works. There are a lot of ways to reduce the friction. In this paper we'll introduce the ways that we have researched during our practice in Bangladesh.

Keywords: Bangladesh, friction and wear, HDD machines, reducing friction

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Authors: Adel Menchawy, Noha Labib

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Many cities have quarters that confer on them sense of identity and place through its cultural history. They are often vital part of the cities charm and appeal, their functional and visual qualities are important to the city’s image and identity. Brownfield sites present an important part of our built landscape. They provide tangible and intangible links to our past and have great potential to play significant roles in the future of our cities, towns and rural environments. Brownfield sites are places that were previously industrial factories or areas that might have had waste kept at that location or been exposed to many types of hazards. Thus its redevelopment revitalizes and strengthens towns and communities as it helps in economic growth, builds community pride and protects public health and the environment Three case studies are discussed in this paper; the first one is the city of Sterling which was developed and revitalized entirely and became a city with identity after it was derelict, the Second is the city of Castlefield with was a place no one was eager to visit now it became a touristic area. And finally the city of Cleveland which adopted a strategy that transferred it from being a polluted, derelict place into a mixed use development city Brownfield revitalization offers a great opportunity to transfer the city from being derelict, useless and contaminated into a place where tourists would love to come. Also it will increase the economy of the place, increase the social level, it can improve energy efficiency, reduce natural consumption, clean air, water and land and take advantage of existing buildings and sites and transfers them into an adaptive reuse after being remediated

Keywords: Brownfield Revitalization, Sustainable Brownfield, Historical conservation, Adaptive reuse

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Authors: Kaling Taki, Rohit Gahlot, Manish Kumar

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Disposal of Sewage Sludge (SS) is a big issue especially in developing nation like India, where there is no control in the dynamicity of SS produced. The present research work demonstrates the potential application of SS amended with varying percentage (0-100%) of Fly Ash (FA) for brick manufacturing as an alternative of SS management. SS samples were collected from Jaspur sewage treatment plant (Ahmedabad, India) and subjected to different preconditioning treatments: (i) atmospheric drying (ii) pulverization (iii) heat treatment in oven (110°C, moisture removal) and muffle furnace (440°C, organic content removal). Geotechnical parameters of the SS were obtained as liquid limit (52%), plastic limit (24%), shrinkage limit (10%), plasticity index (28%), differential free swell index (DFSI, 47%), silt (68%), clay (27%), organic content (5%), optimum moisture content (OMC, 20%), maximum dry density (MDD, 1.55gm/cc), specific gravity (2.66), swell pressure (57kPa) and unconfined compressive strength (UCS, 207kPa). For FA liquid limit, plastic limit and specific gravity was 44%, 0% and 2.2 respectively. Initially, for brick casting pulverized SS sample was heat treated in a muffle furnace around 440℃ (5 hours) for removal of organic matter. Later, mixing of SS, FA and water by weight ratio was done at OMC. 7*7*7 cm3 sample mold was used for casting bricks at MDD. Brick samples were then first dried in room temperature for 24 hours, then in oven at 100℃ (24 hours) and finally firing in muffle furnace for 1000℃ (10 hours). The fired brick samples were then cured for 3 days according to Indian Standards (IS) common burnt clay building bricks- specification (5th revision). The Compressive strength of brick samples (0, 10, 20, 30, 40, 50 ,60, 70, 80, 90, 100%) of FA were 0.45, 0.76, 1.89, 1.83, 4.02, 3.74, 3.42, 3.19, 2.87, 0.78 and 4.95MPa when evaluated through compressive testing machine (CTM) for a stress rate of 14MPa/min. The highest strength was obtained at 40% FA mixture i.e. 4.02MPa which is much higher than the pure SS brick sample. According to IS 1077: 1992 this combination gives strength more than 3.5 MPa and can be utilized as common building bricks. The loss in weight after firing was much higher than the oven treatment, this might be due to degradation temperature higher than 100℃. The thermal conductivity of the fired brick was obtained as 0.44Wm-1K-1, indicating better insulation properties than other reported studies. TCLP (Toxicity characteristic leaching procedure) test of Cr, Cu, Co, Fe and Ni in raw SS was found as 69, 70, 21, 39502 and 47 mg/kg. The study positively concludes that SS and FA at optimum ratio can be utilized as common building bricks such as partitioning wall and other small strength requirement works. The uniqueness of the work is it emphasizes on utilization of FA for stabilizing SS as construction material as a replacement of natural clay as reported in existing studies.

Keywords: Compressive strength, Curing, Fly Ash, Sewage Sludge.

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Authors: Yong Li

Abstract:

Major cities in China has experienced a shift from production based on manufacturing industry to tertiary industry. How to make a better use of existing obsolete industrial land within urban cores has become a difficult problem for many policymakers. City governments regard old manufacturing industrial land as an important source of land to facilitate the development of the cities. Despite the announcement of policies in promoting that, a large portion of industrial land is still not properly redeveloped and most of them became obsolete. The study uses the project of Xinyi International Club as a case to examine the process of adaptive reuse of obsolete industrial space in Guangzhou, China. It attempts to elucidate the underlying mechanisms by identifying the key forces from both the government and the private sectors in influencing the process. The study found that market forces in transforming industrial space are exerting a strong impact on the existing land use planning system in Chinese cities. Pragmatic relaxation of the formal land use the regulatory framework and government supportive land-use intervention have also been crucial towards achieving successful implementation of the restructuring project and making it a showcase. This study questions whether these extraordinary measures, in particular, the use of temporary land use permit, are sustainable in facilitating the transformation of derelict industrial land, and in informing future industrial land-use restructuring policies. It concludes that, while the land use regulatory system in China is becoming increasingly dynamic and flexible, it remains ill-equipped in responding positively to the market, which is characterized by an increasing bargaining power of the private sector. A comprehensive appraisal of the overall impacts of these adaptive re-uses on society is wanting.

Keywords: China, land alteration, obsolete industrial properties, urban planning

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Authors: K. K. Kaidarova, Ye. K. Aibuldinov, Zh. B. Iskakova, G. Zh. Alzhanova, S. Zh. Zayrova

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Currently, the existing road infrastructure of Kazakhstan needs the reconstruction of existing highways and the construction of new roads. The solution to this problem can be achieved by replacing traditional building materials with industrial waste, which in their chemical and mineralogical composition are close to natural raw materials and can partially or completely replace some natural binding materials in road construction. In this regard, the purpose of this study is to develop building materials based on the red sludge of the Pavlodar aluminum plant, blast furnace slag of the Karaganda Metallurgical Plant, lime production waste of the Pavlodar Aluminum Plant as a binder for natural loam. Changes in physical and mechanical properties were studied for uniaxial compression strength, linear expansion coefficient, water resistance, and frost resistance of the samples. Nine mixtures were formed with different percentages of these wastes 1-20:25:4; 2-20:25:6; 3-20:25:8; 4-30:30:4; 5-30:30:6; 6-30:30:8; 7-40:35:4; 8-40:35:6; 9-40:35:8 and the mixture identifier were labeled based on the waste content and composition number. The results of strength measurement during uniaxial compression of the samples showed an almost constant increase in strength and amounted to 0.67–3.56 MPa after three days and 3.33–7.38 MPa after 90 days. This increase in compressive strength is a consequence of the addition of lime and becomes more pronounced over time. The water resistance of the developed materials after 90 days was 7.12 MPa, and the frost resistance for the same period was 7.35 MPa. The maximum values of strength determination were shown by a sample of the composition 9-40:35:8. The study of the mineral composition showed that there was no contamination with heavy metals or dangerous substances. It was determined that road materials made of red sludge, blast furnace slag, lime production waste, and natural loam mixture could be used due to their strength indicators and environmental characteristics.

Keywords: production waste, uniaxial compression, water resistance of materials, frost resistance of samples

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Authors: Rikke Lybæk

Abstract:

This paper delves into the intricacies of recycling household plastic waste within Denmark, employing an exploratory case study methodology to shed light on the technical, strategic, and market dynamics of the plastic recycling value chain. Focusing on circular economy principles, the research identifies critical gaps and opportunities in recycling processes, particularly regarding plastic packaging waste derived from households, with a notable absence in food packaging reuse initiatives. The study uncovers the predominant practice of downcycling in the current value chain, underscoring a disconnect between the potential for high-quality plastic recycling and the market's readiness to embrace such materials. Through detailed examination of three leading companies in Denmark's plastic industry, the paper highlights the existing support for recycling initiatives, yet points to the necessity of assured quality in sorted plastics to foster broader adoption. The analysis further explores the importance of reuse strategies to complement recycling efforts, aiming to alleviate the pressure on virgin feedstock. The paper ventures into future perspectives, discussing different approaches such as biological degradation methods, watermark technology for plastic traceability, and the potential for bio-based and PtX plastics. These avenues promise not only to enhance recycling efficiency but also to contribute to a more sustainable circular economy by reducing reliance on virgin materials. Despite the challenges outlined, the research demonstrates a burgeoning market for recycled plastics within Denmark, propelled by both environmental considerations and customer demand. However, the study also calls for a more harmonized and effective waste collection and sorting system to elevate the quality and quantity of recyclable plastics. By casting a spotlight on successful case studies and potential technological advancements, the paper advocates for a multifaceted approach to plastic waste management, encompassing not only recycling but also innovative reuse and reduction strategies to foster a more sustainable future. In conclusion, this study underscores the urgent need for innovative, coordinated efforts in the recycling and management of plastic waste to move towards a more sustainable and circular economy in Denmark. It calls for the adoption of comprehensive strategies that include improving recycling technologies, enhancing waste collection systems, and fostering a market environment that values recycled materials, thereby contributing significantly to environmental sustainability goals.

Keywords: case study, circular economy, Denmark, plastic waste, sustainability, waste management

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