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Highlights • Differences exist between low and middle income groups to separate waste at source. • Separate methods must be used to involve each group in source separation. • Targeted programmes are needed to overcome indifference among low income groups. • Legislation may fail to increase separation at source participation in both groups. [ABSTRACT FROM AUTHOR]

Abstract Lack of infrastructures, rapid growth in population, high urbanization and unsegregation makes the management of municipal solid waste a difficult task for local authorities. The paper proposes an approach for selecting the waste transfer station locations under unsegregated and segregated waste scenarios in an economical manner. The analytical approach is a combination of two basic components, (i) a mathematical optimization model for the overall cost of municipal solid waste management; and (ii) tools of a geographic information system for creating the dataset of the mathematical model. The novelty in the developed model includes strategic allocation of transfer stations for three scenarios: (i) solid waste collected from sources without segregation (Scenario (I)); (ii) waste collected considering source separation and transfer stations taking only one type of wastes (Scenario (II)); (iii) waste collected under source separation and transfer stations having multiple halls for multiple types of waste (Scenario (III)). The proposed approach has been verified by applying on city of Bilaspur, India. Optimization model selects six best locations for Scenario (I), (II) and five for Scenario (III). Results also show that among the three scenarios studied, scenario (III) is the best as it is providing more profit than scenario (II) and (I). Validity of the model is tested by ANOVA analysis and it suggested key parameters (frequency, operating cost and land value) as significant. This finding suggests that transfer stations with or without multiple halls under source separation environment can earn the profit from solid waste while solving the problem of high collection cost and landfills. Highlights • Mathematical model to find best locations for transfer stations. • Source separation of municipal solid waste along with variation in land cost. • Model validated by applying on a case study. • Significance of key parameters has been tested by ANOVA analysis. [ABSTRACT FROM AUTHOR]

This paper proposes a new method for impulsive source separation (deinterleaving) in multi-input single-output systems based purely on impulse spacing. The impulse spacing for each source is modeled as a renewal process. To classify sources, an algorithm is developed to maximize the likelihood of impulse assignment based on the impulse spacing distributions. A theoretical lower bound on performance is derived and the algorithm is shown to get reasonably close to the bound. The algorithm is extended for use when the impulse spacing distribution parameters are unknown. Performance is evaluated on multiple application examples. [ABSTRACT FROM AUTHOR]

Highlights • Pretreatment of SSO was done at 150–240 °C under 5 different severity index values. • The maximum methane yield of 280 mL/g TCOD added was achieved at 190 °C. • Pretreatment improved solubilization and methane recovery by 50 & 26%, respectively. • A significant correlation was found between soluble COD and methane yield. • Pretreatment temperature beyond 200 °C decreased the methane yield. Abstract The objective of this research was to evaluate the effect of the hydrothermal pretreatment on the solubilization of source separated organics (SSO) as well as the biomethane recovery through the mesophilic batch anaerobic digestion process. For this purpose, the SSO was subjected to fifteen different pretreatment conditions within five different severity index (SI) values (3, 3.5, 4, 4.5, and 5). The pretreatment temperature, holding time, and pressure ranged from 150 to 240 °C, 5 to 30 min, and 476 to 3367 kPa, respectively. The highest solubilization improvement of ∼50% was achieved under the pretreatment condition of "220 °C-10 min-2323 kPa" corresponding to the SI value of 4.5. However, the maximum biomethane production yield of 280 mL/g TCOD added and biomethane production rate of 30 mL/g TCOD added were obtained under the less intense pretreatment conditions of "190 °C-20 min-1247 kPa" and "170 °C-30 min-786 kPa", respectively. [ABSTRACT FROM AUTHOR]

Highlights • New approaches for the management of municipal waste is a must in modern cities. • Environmental benefits should also be considered in waste collection activities. • OPEX associated with underground systems is much more advantageous for the final user. • Vacuum waste collection systems achieves reductions in CO2 emissions above 90% Abstract Waste collection is the activity of transporting solid waste from the point of production to the point of treatment or disposal. Today, the most common way of waste collection is by road from each individual’s house or collecting point. Whilst other services and utilities such as sewage, water, drainage and even modern day telecommunications have wisely been designed to be out of sight in the underground infrastructure, solid waste collection has commonly remained unchanged since the 19th century. Furthermore, traditional municipal waste handling in historical city centres is often made difficult by: old infrastructures; narrow, crooked streets that are not suitable for large waste collection vehicles; little space for rubbish bins, making at source separation difficult, and; high volumes of tourists that make traditional bins less accessible by waste operatives, which often conflicts with the objectives of keeping areas associated with tourism clean and hygienic. In these circumstances, underground vacuum waste collection arise as a revolutionary solution, even in remote areas. This waste management model lets integrate waste collection into the infrastructure of a building, a residential development a district or even entire towns, by transporting waste using vacuum technology through an underground network of pipes. The result, among other positive elements, is an average reduction in CO 2 emissions above 90% compared with traditional collection models by truck. [ABSTRACT FROM AUTHOR]

China has experienced a rapid growth of solid waste over the years, household waste source-separation is becoming a nationwide strategy for promoting recycling economy and improving urban environmental sustainability. Waste separation, however, may end in failure due to the free-rider problem similarly existing in other pro-environmental collective actions. Along with the economic and sociological/social psychological logic respectively, this study tested the effects of economic incentive and social influence, which are theoretically considered as two general solutions to domestic waste separation dilemma. One hundred and eighty-eight residents in the three communities of Hangzhou, Zhejiang Province were assigned to a control group or one of two experimental scenarios, where they were encouraged to participate in waste separation activities through either the economic rewards given on their performance, or door-stepping campaigns aimed at constructing a supportive social environment. Six-month intervention effects were analyzed and showed that economic inducement was more effective than social mobilization in promoting waste separation. Further mediation tests indicated that self-efficacy partially mediated the effects of both strategies, while personal norms were positively associated with two treatments instead of behavior demonstration. In addition, the moderating effects of several socio-demographic factors on psychological mechanisms were also explored. The findings, limitations and implications for future research and policy are discussed in the concluding section. [ABSTRACT FROM AUTHOR]

Recovering nitrogen from separately collected urine can potentially reduce costs and energy of wastewater nitrogen removal and fertilizer production. Through benchtop experiments, we demonstrate the recovery of nitrogen from urine as ammonium sulfate using electrochemical stripping, a combination of electrodialysis and membrane stripping. Nitrogen was selectively recovered with 93% efficiency in batch experiments with real urine and required 30.6 MJ kg N-1 in continuous-flow experiments (slightly less than conventional ammonia stripping). The effects of solution chemistry on nitrogen flux, electrolytic reactions, and reactions with electro-generated oxidants were evaluated using synthetic urine solutions. Fates of urine-relevant trace organic contaminants, including electrochemical oxidation and reaction with electro-generated chlorine, were investigated with a suite of common pharmaceuticals. Trace organics (<0.1 μg L-1) and elements (<30 μg L-1) were not detected at appreciable levels in the ammonium sulfate fertilizer product. This novel approach holds promise for selective recovery of nitrogen from concentrated liquid waste streams such as source-separated urine. [ABSTRACT FROM AUTHOR]

The aim of this study was to mimic real conditions for storage and transport and to evaluate how much of the biomethane potential is lost before the organic fraction of municipal solid waste (OFMSW) from households in Sweden reaches the biogas plant. The laboratory biomethane potential (BMP) experiments was carried out with respect to the storage time, collection method (paper or plastic bag) and storage temperature (22 °C and 6 °C) in order to evaluate the effect of these factors on the biomethane potential. A recipe representative for OFMSW from households in Sweden was designed with the help of literature and modification of recipes from technical reports and scientific literature. Laboratory experiments showed that the difference in the BMP of OFMSW stored in plastic- compared to paper bags were obvious at 22 °C with a lower biomethane potential for paper bags, but there was no difference at 6 °C. Provided that the loss of organic matter during pre-treatment is equivalent for both paper and plastic bags it is possible to get more biomethane from OFMSW collected in plastic bags during the warmest part of the year, since they have a more preservative effect on OFMSW than paper bags. This could be explained by the plastic bags being denser than paper and therefore maintain the volatile organic compounds inside the bag and promote a pre-hydrolysis of the material rather than aerobic degradation. [ABSTRACT FROM AUTHOR]

This work aims to assess the operation of the first large scale segregated biowaste composting scheme in Greece to divert Household Food Waste (HFW) from landfill and produce a material which can be recovered and used as compost. The source separation and collection of HFW was deployed in selected areas in Attica Region serving about 3700 households. Sorted HFW is collected & transported to the Mechanical and Biological Treatment (MBT) plant in Attica Region that has been designed to produce Compost Like Output (CLO) from mixed MSW. The MBT facility has been adjusted in order to receive and treat aerobically HFW mixed with shredded green waste in a dedicated composting tunnel. The composting process was monitored against temperature, moisture and oxygen content indicating that the biological conditions are sufficiently developed. The product quality was examined and assessed against the quality specifications of EU End of Waste Criteria for biowaste subjected to composting aiming to specify whether the HFW that has undergone recovery ceases to be waste and can be classified as compost. More specifically, the heavy metals concentrations (Cr, Cu, Ni, Cd, Pb, Zn and Hg) are within the set limits and much lower compared to the CLO material that currently is being produced at the MBT plant. In regard to the hygienic requirements of the product it has been found that the process conditions result in a pathogen free material (i.e. E. Coli and Salmonella ) which does not favor the growth of viable weeds and plant propagules, while it acquires sufficient organic matter content for soil fertilization. Noticeable physical impurities (mainly fractions of glass) have been detected exceeding the quality control threshold limit of 0.5% w/w (plastics, metals and glass). The latter is related to the missorted materials and to the limited pre-treatment configurations prior to composting. The above findings indicate that effective source separation of biowaste is prerequisite for good quality production and marketing of compost and special consideration should be made to minimize glass impurities prior composting (i.e. awareness raising and pretreatment stage). Therefore, it is feasible to gradually replace the production of questionable quality CLO in MBTs with biowaste compost which is in line with the required quality control standards especially when heavy metals concentrations is concerned. [ABSTRACT FROM AUTHOR]

Zero-discharge constructed wetland environments are more prone to the accumulation of pollutants. The relationship between filter media and microbial communities in this type of environment is still poorly known. We conducted bench-scale studies of different filter media (polyurethane foam, blast-furnace slag, and loofah) in these systems by simulating the batch operation with light greywater for 433 days. Physicochemical and microbiological analyses (scanning electron microscopy and polymerase chain reaction electrophoresis denaturing gradient gel) were used. In all systems, anoxic environments prevailed. These environments were crucial for methanogenesis and sulfidogenesis processes, which are primarily responsible for organic material conversion. The chemical oxygen demand/sulfate (COD/SO42−) ratio was the limiting factor in the competition of microorganisms involved in these processes. This condition, combined with the neutral-alkaline pH, also allowed Chloroflexi phylum bacteria to oxidize sulfide to sulfate and elemental sulfur in all studied media. The results showed strong evidence supporting that the microbial community formed in the present study is more related to operational/environmental conditions than to the different tested filter media. Thus, this demonstrates that the control of interactive effects between pH, redox potential, and the COD/SO42−ratio can prevent the accumulation and/or release of sulfide in anoxic environments. [ABSTRACT FROM PUBLISHER]

Source separation systems for the management of domestic wastewater and food waste has been suggested as more sustainable sanitation systems for urban areas. The present study used an attributional life cycle assessment to investigate the carbon footprint and potential for nutrient recovery of two sanitation systems for a hypothetical urban area in Southern Sweden. The systems represented a typical Swedish conventional system and a possible source separation system with increased nutrient recovery. The assessment included the management chain from household collection, transport, treatment and final return of nutrients to agriculture or disposal of the residuals. The results for carbon footprint and nutrient recovery (phosphorus and nitrogen) concluded that the source separation system could increase nutrient recovery (0.30–0.38 kg P capita −1 year −1 and 3.10–3.28 kg N capita −1 year −1 ), while decreasing the carbon footprint (−24 to −58 kg CO 2 -eq. capita −1 year −1 ), compared to the conventional system. The nutrient recovery was increased by the use of struvite precipitation and ammonium stripping at the wastewater treatment plant. The carbon footprint decreased, mainly due to the increased biogas production, increased replacement of mineral fertilizer in agriculture and less emissions of nitrous oxide from wastewater treatment. In conclusion, the study showed that source separation systems could potentially be used to increase nutrient recovery from urban areas, while decreasing the climate impact. [ABSTRACT FROM AUTHOR]

Until recently there has been little, if any, concern over revamping let alone improving wastewater management system in Zimbabwe's urban areas given the dominance and institutionalised water-borne system. Yet, the current constraints in this system and the immensity of urbanisation in the country begs and compels planners, engineers and systems thinkers to rethink what best can work as a sustainable wastewater system. With particular reference to the ever-expanding Harare metropolitan region, this article provides an evaluative analysis on the potentiality, risks and strategies that can be adopted by Harare and its satellites in addressing the problems of the conventional wastewater management system. The suggested framework of operation is a decentralised domestic wastewater collection and treatment system which however has its own multifarious risks. Using systems dynamics conceptualisation of the potentiality, opportunities, risks and strategies, the paper seeks to model the path and outcomes of this decentralised domestic wastewater collection and treatment system and also suggests a number of policy measures and strategies that the city of Harare and its satellites can adopt. [ABSTRACT FROM AUTHOR]

Efficient and economic reuse of waste is one of the pillars of modern environmental engineering. In the field of domestic sewage management, source separation of yellow (urine), brown (faecal matter) and grey waters aims to recover the organic substances concentrated in brown water, the nutrients (nitrogen and phosphorous) in the urine and to ensure an easier treatment and recycling of grey waters. With the objective of emphasizing the potential of recovery of resources from sewage management, a lab-scale research study was carried out at the University of Padova in order to evaluate the performances of oleaginous plants (suitable for biodiesel production) in the phytotreatment of source separated yellow and grey waters. The plant species used were Brassica napus (rapeseed), Glycine max (soybean) and Helianthus annuus (sunflower). Phytotreatment tests were carried out using 20 L pots. Different testing runs were performed at an increasing nitrogen concentration in the feedstock. The results proved that oleaginous species can conveniently be used for the phytotreatment of grey and yellow waters from source separation of domestic sewage, displaying high removal efficiencies of nutrients and organic substances (nitrogen > 80%; phosphorous > 90%; COD nearly 90%). No inhibition was registered in the growth of plants irrigated with different mixtures of yellow and grey waters, where the characteristics of the two streams were reciprocally and beneficially integrated. [ABSTRACT FROM AUTHOR]

A paradigm shift to waste reuse has started in the wastewater sector with many experts calling for greater resource recovery, often facilitated by alternative solutions such as source separation. Source separation has been shown to be advantageous for improving treatment capacity, food security, and efficiency; yet these systems are still immature, considered risky by professionals and scarcely implemented. This study attempts to answer the question of why source separation is still marginalized by examining the Swedish experience with source separated wastewater from the perspective of Technology Innovation Systems (TIS) in order to identify obstacles and policy recommendations. Considering that source-separation is still in a development phase, the study found that source separation works moderately well within the on-site niche and that blackwater systems in general perform better than urine diversion. Knowledge development is found to be the weakest function. A major blocking mechanism is the weakness of interchange between knowledge development and entrepreneurial activity. Policy recommendations include: increased R&D; building networks and communication platforms; and establishing guidelines for technologies, legislation interpretation and organizational models. [ABSTRACT FROM AUTHOR]

The aim of single channel source separation is to accurately recover signals from mixtures. Non-negative matrix factorization (NMF) is a popular method to separate mixed signals using learned dictionaries. These dictionaries can be produced efficiently by sparse NMF to approximate the input signal as closely as possible. However, the literature does not consider the structure of the data in terms of the similarity among vertices of the input signal. Furthermore, state-of-art variants of NMF that are more efficient than conventional ones have not been utilized, and the learned dictionary is typically fixed in the separating phase. This strategy is not favorable because the training data and the testing data totally differ. To deal with these issues, our work proposes a method that incorporates the graph regularization into group sparsity ß-NMF to improve the performance of source separation. The proposed algorithms differ from those in the literature by using an adaptive dictionary in which particular characteristics of the testing data are updated to produce newer dictionaries. Experimental results demonstrate that our proposed method is outstandingly effective in speech separation in various scenarios, relative to the baseline. [ABSTRACT FROM AUTHOR]

Proper management of food waste, a major component of municipal solid waste (MSW), is needed, especially in developing Asian countries where most MSW is disposed of in landfill sites without any pretreatment. Source separation can contribute to solving problems derived from the disposal of food waste. An organic waste source separation and collection programme has been operated in model areas in Hanoi, Vietnam, since 2007. This study proposed three key parameters (participation rate, proper separation rate and proper discharge rate) for behaviour related to source separation of household organic waste, and monitored the progress of the programme based on the physical composition of household waste sampled from 558 households in model programme areas of Hanoi. The results showed that 13.8% of 558 households separated organic waste, and 33.0% discharged mixed (unseparated) waste improperly. About 41.5% (by weight) of the waste collected as organic waste was contaminated by inorganic waste, and one-third of the waste disposed of as organic waste by separators was inorganic waste. We proposed six hypothetical future household behaviour scenarios to help local officials identify a final or midterm goal for the programme. We also suggested that the city government take further actions to increase the number of people participating in separating organic waste, improve the accuracy of separation and prevent non-separators from discharging mixed waste improperly. [ABSTRACT FROM AUTHOR]

A case study on the source separation of municipal solid waste (MSW) was performed in Changsha, the capital city of Hunan Province, China. The objective of this study is to analyze the effects of different separation methods and compare their effects with citizens’ attitudes and inclination. An effect evaluation method based on accuracy rate and miscellany rate was proposed to study the performance of different separation methods. A large-scale questionnaire survey was conducted to determine citizens’ attitudes and inclination toward source separation. Survey result shows that the vast majority of respondents hold consciously positive attitudes toward participation in source separation. Moreover, the respondents ignore the operability of separation methods and would rather choose the complex separation method involving four or more subclassed categories. For the effects of separation methods, the site experiment result demonstrates that the relatively simple separation method involving two categories (food waste and other waste) achieves the best effect with the highest accuracy rate (83.1%) and the lowest miscellany rate (16.9%) among the proposed experimental alternatives. The outcome reflects the inconsistency between people’s environmental awareness and behavior. Such inconsistency and conflict may be attributed to the lack of environmental knowledge. Environmental education is assumed to be a fundamental solution to improve the effect of source separation of MSW in Changsha. Important management tips on source separation, including the reformation of the current pay-as-you-throw (PAYT) system, are presented in this work. Implications: A case study on the source separation of municipal solid waste was performed in Changsha. An effect evaluation method based on accuracy rate and miscellany rate was proposed to study the performance of different separation methods. The site experiment result demonstrates that the two-category (food waste and other waste) method achieves the best effect. The inconsistency between people’s inclination and the effect of source separation exists. The proposed method can be expanded to other cities to determine the most effective separation method during planning stages or to evaluate the performance of running source separation systems. [ABSTRACT FROM PUBLISHER]

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Recently, research on source separation followed by the treatment of urine and/or resource recovery from human urine has shown promise as an emerging management strategy. Despite contributing only 1% of the total volume of wastewater, human urine contributes about 80% of the nitrogen, 70% of the potassium, and up to 50% of the total phosphorus in wastewater. It is also a known fact that many of the micropollutants, especially selected estrogens, get into municipal wastewater through urine excretion. In this research, we investigated the fate of 17β-estradiol (E2) as a model estrogen during struvite precipitation from synthetic urine followed by the treatment of urine using a partial nitritation-anammox (PN/A) system. Single-stage and two-stage suspended growth PN/A configurations were used to remove the nitrogen in urine after struvite precipitation. The results showed an almost 95% phosphorous and 5% nitrogen recovery/removal from the synthetic urine due to struvite precipitation. The single and two stage PN/A processes were able to remove around 50% and 75% of ammonia and nitrogen present in the post struvite urine solution, respectively. After struvite precipitation, more than 95% of the E2 remained in solution and the transformation of E2 to E1 happened during urine storage. Most of the E2 removal that occurred during the PN/A process was due to sorption on the biomass and biodegradation (transformation of E2 to E1, and slow degradation of E1 to other metabolites). These results demonstrate that a combination of chemical and biological unit processes will be needed to recover and manage nutrients in source separated urine. [ABSTRACT FROM AUTHOR]

Municipal solid waste has been considered as one of the most immediate and serious problems confronting urban government in most developing and transitional economies. Providing solid waste performance highly depends on the effectiveness of waste collection and transportation process. Generally, this process involves a large amount of expenditures and has very complex and dynamic operational problems. Source separation has a major impact on effectiveness of waste management system as it causes significant changes in quantity and quality of waste reaching final disposal. To evaluate the impact of effective source separation on waste collection and transportation, this study adopts a decision support tool to comprehend cause-and-effect interactions of different variables in waste management system. A system dynamics model that envisages the relationships of source separation and effectiveness of waste management in Bangkok, Thailand is presented. Influential factors that affect waste separation attitudes are addressed; and the result of change in perception on waste separation is explained. The impacts of different separation rates on effectiveness of provided collection service are compared in six scenarios. ‘Scenario 5’ gives the most promising opportunities as 40% of residents are willing to conduct organic and recyclable waste separation. The results show that better service of waste collection and transportation, less monthly expense, extended landfill life, and satisfactory efficiency of the provided service at 60.48% will be achieved at the end of the simulation period. Implications of how to get public involved and conducted source separation are proposed. [ABSTRACT FROM AUTHOR]

On-site treatment of black water generated at a residential school was investigated by employing an upgraded two-stage package system: a modified septic tank followed by an anaerobic filter. The findings revealed that the average removal efficiency for COD tot , COD ss , BOD and TSS were 72.6, 90.2, 78.4 and 83.2%, respectively. Monthly septage characterization revealed a declining trend in VSS/TSS ratio, which indicated the progressive hydrolysis as well as stabilization of the sludge. The interrelationship between physico-chemical and microbial parameters revealed a linear relationship between the data with a good coefficient of correlation. High methanogenic activity of 0.386 g CH 4 /g VSS. D was observed within the developed sludge. Thus the studied package system can be a suitable alternative to the conventional septic tank for on-site treatment of black water in the rural areas of developing regions. [ABSTRACT FROM AUTHOR]

To address issues of poor sanitation and water scarcity in developing countries, innovative wastewater management systems should be proposed, based on considerations of life cycle and local environmental impacts. Source-separation separates urine, feces, and gray water, enhancing the reuse of nutrients, and is considered a promising wastewater treatment method. This study evaluates the life cycle and local environmental impacts of source-separation systems. Each system was set to achieve the same effluent quality as the functional unit. Four scenarios were examined: offsite treatment (B1), onsite treatment (B2), source-separation (A1), and pour-flush toilet use (A2). The study area was a hypothetical village in the municipality of Tianjin in China, which has experienced severe water shortages and poor sanitation. Life cycle impacts such as global warming, acidification, and eutrophication were evaluated using a life cycle assessment (LCA) framework, and direct water use was evaluated as the local impact. The scenarios enhancing nutrient recovery (B2 and A2) showed significant benefit by avoiding mineral fertilizer use; however, the source-separation system (A1) showed the best performance in terms of life cycle environmental impacts, which supports the findings of several previous LCA studies with similar system boundaries. Within the selected framework and assumptions, the results show that the source-separation system had the best environmental performance in terms of direct water use and the lifecycle impact categories. [ABSTRACT FROM AUTHOR]

There is increasing interest in source separation and treatment of urine so as to recover nitrogen and phosphate more efficiently than treating combined wastewater. Although previous studies primarily focused on struvite precipitation for the recovery of phosphorus, the composition of urine changes during storage. The present study compared the precipitation conditions for fresh urine and hydrolyzed urine. The optimal conditions for struvite crystallization were obtained from orthogonal experiment and single-factor optimization. The pH of fresh urine should be adjusted to around 9.5-10.0 to make the reaction thorough, while this was unnecessary for hydrolyzed urine. To reduce cost, magnesite was selected as an alternative for pure MgO, which presented similar efficiency for phosphate recovery. About 92.4% of phosphorus and 87.2% of ammonia-nitrogen were recovered from urine when adding 2.5 g/L of magnesite and 375 g/L of zeolite to get struvite crystals and nitrogen-rich zeolite as a slow-release fertilizer. [ABSTRACT FROM AUTHOR]

A questionnaire survey consisting of 2400 householders was performed on Abadan residents to evaluate their knowledge, attitudes, and practices (KAP) towards solid waste (SW) reduction, source separation and recycling, collection and willingness to pay (WTP) for SW services. The study has also covered the relationship between demographic variables and KAP towards SW management. The data analyzed suggests that the studied community had a very positive attitude to take part in SW source separation and recycling plans. However, the respondents not only showed low intimate knowledge of different steps of SW management, but were also weak to take practices about these steps. The KAP of SW source separation and recycling was influenced by demographic factors of age, education level, gender and occupation. It was further found that education level and occupation were two significant factors affecting residents’ WTP (χ 2 = 24.083, p -value <0.0001). In conclusion our study found that providing public with MSW infrastructures and improving citizens’ awareness about SW source separation and recycling to promote SW recycling programs hold great promise for developing effective public campaigns and behavior-changing interventions. This has important implications in that the usual KAP of public proved inadequate in the case of SW source separation and recycling. The implementation of needs-based training programmes considering females as one of the main audience groups and determination of municipality needs are thereby highly advocated. [ABSTRACT FROM AUTHOR]

Hydroponic systems are widely used for the treatment of nutrient rich wastewaters. In this study, a hydroponic system was applied as the final treatment stage of source-separated human urine after urea hydrolysis, induced-struvite precipitation and ammonia stripping in tropical conditions (Singapore). The results showed that water spinach grew efficiently in the pretreated urine with 1:50 dilution ratio at the growth rate 0.68 cm/d, leaf number 2.27 pieces/d, shoot dry mass 0.33 g, water content 93.86%, and nitrogen and potassium conversion rate 0.46 and 0.51 mg/mg, respectively. This hydroponic system removed 58–66% chemical oxygen demand (COD), 41–49% total nitrogen (TN) and up to 47% total suspended solid (TSS), indicating sufficient urine stream polishing. Nitrification was observed when COD reduced by 60%, possibly because of oxygen competition between nitrobacteria for nitrification and microbes for COD degradation. The kinetic study revealed that zero-order model provided best fitting for COD and ammonia-nitrogen (NH 4 + -N) removal, while second-order model was more suitable for TN removal. [ABSTRACT FROM AUTHOR]

Wastewater from a source-separated sanitation system connected to 24 residential flats was analysed for the content of organic matter and nutrients and other key parameters for microbiological processes used in the treatment and reuse of wastewater. Black water (BW) was the major contributor to the total load of organic matter and nutrients in the wastewater, accounting for 69% of chemical oxygen demand (COD), 83% of total nitrogen (N) and 87% of phosphorus (P). With a low COD/N ratio and high content of free ammonia, treating BW alone is a challenge in traditional biological nitrogen removal approaches. However, its high nitrogen concentration (1.4–1.7 g L-1) open up for nutrient reuse as well as for novel, more energy efficient N-removal technologies. Grey water (GW) contained low amounts of nutrients relative to organic matter, and this may limit biological treatment processes under certain conditions. GW contains a higher proportion of soluble, readily degradable organic substances compared with BW, which facilitates simple, decentralized treatment approaches. The concentration of organic matter and nutrients varied considerably between our study and other studies, which could be related to different toilet flushing volumes and water use habits. The daily load per capita, on the other hand, was found to be in line with most of the reported studies. [ABSTRACT FROM AUTHOR]