Resource Recovery Potential Research Articles

Recovery of resources from end-of-life passenger cars in the informal sector in India

Sustainable management of vehicles at their end-of-life stage (ELVs) offers a significant potential for resource recovery by closing the material loop and thus contributes to dealing with scarcity of resources. Although ELVs till date in countries like India are considered as waste and not as secondary resource material (SRM), but, if used judiciously, may obviate the extraction of primary or virgin materials. Although policymakers have focused on ways to ensure higher resource efficiency in the automobile sector, research on the role of the informal sector in recovering useful materials and parts from ELVs is limited. The present study examines the current situation of ELV processing at Mayapuri scrap market, one of the largest informal markets for ELVs in Asia wherein, mass-balance approach is used to examine how hatchback cars are disposed. A conceptual framework depicting process flow and the interactions between the multiple stakeholders involved in this sector has been developed. Further, approximately 7% of aluminium and 76% of iron, by weight, were recovered from the sampled hatchback cars. These results were used for estimating the potential to recycle and to recover useful materials from ELVs that are processed by the informal sector in India. Under the business-as-usual scenario, the estimates show that the sector can recover about 0.34 million tonnes of aluminium and 4.03 million tonnes of iron by 2030. These figures indicate the huge potential of this sector in a circular economy and highlight the need to make operations in this sector more formal and to include informal players in the value chain to address the scarcity of these resource.

Life Cycle Assessment of Community-Based Sewer Mining: Integrated Heat Recovery and Fit-For-Purpose Water Reuse

Municipal sewage contains significant embedded resources in the form of chemical and thermal energy. Recent developments in sustainable technology have pushed for the integration of resource recovery from household wastewater to achieve net zero energy consumption and carbon-neutral communities. Sewage heat recovery and fit-for-purpose water reuse are options to optimize the resource recovery potential of municipal wastewater. This study presents a comparative life cycle assessment (LCA) focused on global warming potential (GWP), eutrophication potential (EUP), and human health carcinogenic potential (HHCP) of an integrated sewage heat recovery and water reuse system for a hypothetical community of 30,000 people. Conventional space and water heating components generally demonstrated the highest GWP contribution between the different system components evaluated. Sewage-heat-recovery-based district heating offered better environmental performance overall. Lower impact contributions were demonstrated by scenarios with a membrane bioreactor (MBR) and chlorination prior to water reuse applications compared to scenarios that use more traditional water and wastewater treatment technologies and discharge. The LCA findings show that integrating MBR wastewater treatment and water reuse into a district heating schema could provide additional environmental savings at a community scale.

A decision-support framework for techno-economic-sustainability assessment of resource recovery alternatives

The careful consideration of technology readiness, economics and sustainability holds the key to identifying and then transitioning a resource recovery opportunity into actual implemented solution. Currently this decision-making process is carried out based on in-house experience of stake-holders as there is no established framework that can be followed. This work presents a systematic computer-aided decision-support framework to tackle challenges faced when attempting to identify and develop resource recovery projects. The framework is hierarchical and combines key evaluation aspects in one integrated approach. The framework will enable industries transition towards more sustainable production, providing users with the opportunity to evaluate and support decisions on not only a financial basis, but also from a comprehensive techno-economic and sustainability angle. To this end, the framework collects relevant aspects within the sustainability field and addresses concepts such as circular economy, resource recovery, and waste management. This research also aims to add additional relevant inputs for increasing the possibilities to reach the scope of cleaner production. The proposed methodology is generic and can be applied to a wide variety of potential resource recovery projects. The application of the framework is highlighted through an industrial case study of the monosaccharide recovery from wheat straw liquor in bio-refinery setting.

Waste-to-Resource value chain optimisation: Combining spatial, chemical and technoeconomic aspects

Due to complex composition of carbohydrates, lipid, protein, cellulose, hemicellulose and lignin, wastewater (WW) and organic fraction municipal solid waste (OFMSW) represent nutrient and carbon rich resources. Conventionally, value chains in the waste sector have considered OFMSW and WW as unwanted by-products as opposed to potential valuable resources. Full exploitation of these resources calls for a value chain transformation towards proactive resource recovery. This study focuses on the waste supply chain optimisation to recover value added products from OFMSW.The research leads to a systems-modelling approach, which integrates spatial data analyses, mathematical mixed integer linear programming (MILP) optimisation and technology performance evaluation to inform the design of waste-to-resource value chains. A UK based study on OFMSW is presented to demonstrate the efficacy of the approach. The study captures variation in OFMSW quantity and composition, incorporating over 600 existing anaerobic digestion (AD) operational plants in the UK, while potential sites for new waste-recovery facilities are identified, accounting for transportation and logistics, using a GIS-based analysis. Key outcomes are analysed (technology type, size, location, logistical connections), placing emphasis on the need to consider the value of the resource recovery potential over the lifetime of an AD or thermochemical treatment facility in the design process. Such an approach offers a promising pathway for tackling the open challenges currently hindering the waste-to-resource transformation.

A Review of Landfill Leachate Treatment by Microalgae: Current Status and Future Directions

Solid waste generation has been projected to increase worldwide. Presently, the most applied methodology to dispose of solid waste is landfilling. However, these landfill sites, over time release a significant quantity of leachate, which can pose serious environmental issues, including contamination of water resources. There exist many physicochemical and biological landfill leachate treatment schemes with varying degrees of success. With an increasing focus on sustainability, there has been a demand for developing eco-friendly, green treatment schemes for landfill leachates with viable resource recovery and minimum environmental footprints. Microalgae-based techniques can be a potential candidate for such a treatment scenario. In this article, research on microalgae-based landfill leachate treatments reported in the last 15 years have been summarized and critically reviewed. The scale-up aspect of microalgae technology has been discussed, and the related critical factors have been elucidated. The article also analyzes the resource recovery potential for microalgal techniques with respect to leachate treatment and explores possible methodologies to minimize the environmental footprints of the microalgae-based treatment process. The future research potential in the area has been identified and discussed.

A Study on Solid Waste Generation of Household and Potential of Resource Recovery in Dhaka, Bangladesh

Rapid population growth in Dhaka has resulted in excess generation of solid waste. Present solid waste management authority of Dhaka City Corporation is struggling to manage this huge amount of waste properly as there is no framework on solid waste management. The purpose of this work is to identify the present waste generation per person (Kg/person/day) in a housing society of Dhaka city and possible resource recovery potential of solid waste of the area so that the correspondent authority can have a scope of finding a framework for effective management of solid waste. The survey was conducted in 100 households of Mirpur Defense Officers’ Housing Society, (DOHS) Dhaka. These households were classified into five groups according to monthly income ranging from 60,000 BDT to 160,000 BDT. The total population of the area was around 15,000. Average waste generation was found 0.74 Kg/person/ day. Around 11.10 tons of solid waste was generated per day and major fraction was food waste (on average 69.90%). About 226 Kilograms of solid waste can easily be achievable for using as compost component every day. Possible energy recovery from generated waste was equivalent to 3428.70 Kwh of electricity per day

Effect of selenate and thiosulfate on anaerobic methanol degradation usingactivated sludge.

Anaerobic bioconversion of methanol was tested in the presence of selenate (SeO42-), thiosulfate (S2O32-), and sulfate (SO42-) as electron acceptors. Complete SeO42- reduction occurred at COD:SeO42- ratios of 12 and 30, whereas ~ 83% reduction occurred when the COD:SeO42- ratio was 6. Methane production did not occur at the three COD:SeO42- ratios investigated. Up to 10.1 and 30.9% of S2O32- disproportionated to SO42- at COD:S2O32- ratios of 1.2 and 2.25, respectively, and > 99% reduction was observed at both ratios. The presence of S2O32- lowered the methane production by 73.1% at a COD:S2O32- ratio of 1.2 compared to the control (no S2O32-). This study showed that biogas production was not preferable for SeO42- and S2O32--rich effluents and volatile fatty acid production could be a potential resource recovery option.

Exploring resource recovery potentials for the aerobic granular sludge process by mass and energy balances – energy, biopolymer and phosphorous recovery from municipal wastewater

Mass and energy balances are an excellent tool to explore the integration of resource recovery technologies into wastewater treatment processes and reveal recoverable resource quantities and occurring trade-offs at an early process design stage.

Effects of Light on Saccharide Wastewater Treatment and Resource Recovery by Proteiniphilum acetatigenes PSB-W

Photosynthetic bacteria (PSB) wastewater treatment is a new method with great resource recovery potential. In order to improve the biomass and valuable resources of bacteria in the wastewater treatment of photosynthetic bacteria, the effects of different light conditions on the efficiency of Proteiniphilum acetatigenes PSB-W in the treatment of sugar wastewater and the production of bacteria and carotenoids in the wastewater were analyzed from three aspects of light source, light intensity and light period. Under the principle of priority of pollutant removal efficiency, the red LED light was selected with the light intensity of 4000 Lux, 16L (light):8D (dark) for light cycle, and the best efficiency of wastewater removal and bacterial yield were obtained when the culture time was 3d, Chemical oxygen demand (COD) removal rate was 80.9%, bacterial OD600 was 0.907 ± 0.023, carotenoid yield was 7.83 ± 0.27 mg/L, respectively. These results show that PSB-W strains can provide more biomass and valuable substances in suitable environment. It provides a theoretical basis for the realization of wastewater recycling.

Status and Potential of Resource Recovery from Municipal Solid Waste in Kathmandu Valley, Nepal

Current waste management strategies are shifting from waste disposal to recycling and recovery and are considering waste as a potential new resource. This paper aims to quantify reusable and recyclable fractions with status of material recovery from municipal solid waste (MSW) in Kathmandu Valley of Nepal. 550 households, 110 institutions and 110 commercial establishments were sampled to compute the generation, composition and quantify reusable and recyclable fraction of solid waste. In addition, 120 scrap shops were surveyed randomly from Kathmandu Valley to estimate the amount of resource recovered for economic benefits. As per results, the average per capita MSW generation can be estimated at range of 0.25 kg day-1 to 0.47 kg day-1 in municipalities of Kathmandu Valley. Based on these generation rates and population for the year 2011, the total MSW generation of the five municipalities of Kathmandu Valley was estimated to be 620 metric tonnes day-1. The major content of reusable and recyclable materials in MSW comprised with an average of 44% that is equivalent to 271 metric tonnes day-1 among which only 52% (i.e. 140 metric tonnes day-1) of these materials were found to be recovered during survey. The key materials that have been recovered are papers, plastics, metals, glasses, and batteries. Recovery of reusable and recyclable materials not only helps to minimize the quantity of solid waste for land filling, but also provides a potential source of livelihood for the urban poor.

Wastewater treatment technology selection under various influent conditions and effluent standards based on life cycle assessment

Influent concentration and effluent standards have strong impacts on technology selection by wastewater treatment plants (WWTPs) and on resource recovery processes. In this paper, resource recovery simulation scenarios incorporated with conventional WWTP models were designed in an imitation of typical existing facilities. We integrated economic analysis and a life cycle assessment to evaluate the impacts of treatment technologies selected for different influent conditions and effluent standards. The results revealed that high concentration influents required the most complicated treatment processes to meet a strict effluent standard. The pattern of total impacts was strongly dependent on the influent conditions. High concentration influent was found to correlate with low energy consumption, low costs, a high nutrient recovery potential but also a high global warming potential when removing 1 kg of pollutants. The incorporation of resource recovery improved the overall performance of WWTPs; however, low concentration influents were not suitable for resource recovery due to their limited benefits. The strict effluent standard limited the resource recovery potential from wastewater, and a loose effluent standard may improve the resource recovery performance, especially for high concentration influents.

Contamination of N-poor wastewater with emerging pollutants does not affect the performance of purple phototrophic bacteria and the subsequent resource recovery potential

Propagation of emerging pollutants (EPs) in wastewater treatment plants has become a warning sign, especially for novel resource-recovery concepts. The fate of EPs on purple phototrophic bacteria (PPB)-based systems has not yet been determined. This work analyzes the performance of a photo-anaerobic membrane bioreactor treating a low-N wastewater contaminated with 25 EPs. The chemical oxygen demand (COD), N and P removal efficiencies were stable (76 ± 8, 62 ± 15 and 36 ± 8 %, respectively) for EPs loading rate ranging from 50 to 200 ng L-1 d-1. The PPB community adapted to changes in both the EPs concentration and the organic loading rate (OLR) and maintained dominance with >85 % of total 16S gene copies. Indeed, an increment of the OLR caused an increase of the biomass growth and activity concomitantly with a higher EPs removal efficiency (30 ± 13 vs 54 ± 11 % removal for OLR of 307 ± 4 and 590 ± 8 mgCOD L-1 d-1, respectively). Biodegradation is the main mechanism of EPs removal due to low EPs accumulation on the biomass, the membrane or the reactor walls. Low EPs adsorption avoided biomass contamination, resulting in no effect on its biological methane potential. These results support the use of PPB technologies for resource recovery with low EPs contamination of the products.

Characterization and mitigation of the fouling of flat-sheet ceramic membranes for direct filtration of the coagulated domestic wastewater

Ceramic membranes allow a high filtration flux with a low fouling propensity. Direct filtration of municipal wastewater using flat-sheet ceramic membranes (FSCM) is an attractive and promising technology for wastewater treatment and resource recovery. Urgent need is to determine the fouling behavior of FSCM and its optimal cleaning strategy in direct filtration applications. This study was conducted on pre-coagulation of sewage with FeCl3 (20 mg Fe/L) or polyaluminum chloride (15 mg Al/L), followed by FSCM filtration at around 1.0 m/d (as high as 41.7 L/m2-h in flux). The results showed that the coagulation-FSCM filtration removed chemical oxygen demand and total phosphorus by up to 90.0% and 99.9%, respectively. The pollutants (organics and nutrients) in the sewage influent were concentrated into the sludge for potential resource recovery. Without pre-coagulation, foulants easily entered the membrane pores, causing rapid membrane fouling. Chemically enhanced coagulation greatly decreased the membrane fouling rate by aggregating various foulants into flocs. Fouled membranes were effectively renewed by physical means, such as water flushing and sonication, or a short period of chemical backwashing with NaOH, HCl or oxidizing agents. The study revealed the fouling mechanisms of FSCM in sewage filtration and developed effective cleaning strategies for its long-term operation.

Incorporating Location Aspects in Process Integration Methodology

The large potential for waste resource and heat recovery in industry has been motivating research toward increasing efficiency. Process integration methods have proven to be effective tools in improving industrial sites while decreasing their resource and energy consumption; however, location aspects and their impact are generally overlooked. This paper presents a method based on process integration, which considers the location of plants. The impact of the locations is included within the mixed integer linear programming framework in the form of heat losses, temperature and pressure drop, and piping cost. The objective function is selected as minimisation of the total cost of the system excluding piping cost and ϵ -constraints are applied on the piping cost to systematically generate multiple solutions. The method is applied to a case study with industrial plants from different sectors. First, the interaction between two plants and their utility integration are illustrated, depending on the piping cost limit which results in the heat pump and boiler on one site being gradually replaced by excess heat recovered from the other plant. Then, the optimisation of the whole system is carried out, as a large-scale application. At low piping cost allowances, heat is shared through high pressure steam in above-ground pipes, while at higher piping cost limits the system switches toward lower pressure steam sharing in underground pipes. Compared to the business-as-usual operation of the sites, the optimal solution obtained with the proposed method leads to 20% reduction in the overall cost of the system, including the piping cost. Further reduction in the cost is possible using a state of the art method but the technical and economic feasibility is not guaranteed. Thus, the present work provides a tool to find optimal industrial symbiosis solutions under different investment limits on the infrastructure between plants.

Food waste from a university campus in the Middle East: Drivers, composition, and resource recovery potential

Food waste is a pressing issue that imposes economic, social and environmental impacts on both developing and developed countries. This study analyzes quantitatively and qualitatively the generated food waste at various food outlets of a university campus in Qatar. It is a fundamental step to manage the issue of food waste from educational institutes. The investigation comprised four stages: screening, sampling, surveying, and synthesis. Food waste generation at the sampled locations was estimated at 329.5 kg/day or 80 t/year. Based on per sales estimates, total food waste was 980 g/sale and 757 g/sale at the student male and female housing complexes, respectively, equating to roughly one wasted meal for each sold meal. The majority of this waste was avoidable waste and the root cause for the excessive food waste generation was overproduction rather than consumer wastage. The study found that the main food provider, who primarily serves buffet style meals, lacks the proper tools to measure food waste generated at their cafeterias. Past experience was the primary tool to support the company’s demand management estimation which has proven unsuccessful and highlights the need to not only educate the consumer but also food providers. Possible treatments routes are discussed based on food waste characterization findings.

Elucidating pyrolysis behaviour of activated sludge in granular and flocculent form: Reaction kinetics and mechanism

The pyrolysis kinetics of sewage sludge was studied to determine the constituent of sludge and explore the feasibility of pyrolytic post-treatment. Both flocculent sludge and granular sludge were pyrolysed in a thermogravimetric analyser under inert atmospheric conditions. The pyrolysis of granular sludge and flocculent sludge were described by three parallel reactions model with three individual pseudo-components. The decomposition activation energy values of the three pseudo-components were determined by iso-conversional methods to be 263.97 kJ/mol, 257.18 kJ/mol and 153.61 kJ/mol in flocculent sludge and 139.89 kJ/mol, 228.78 kJ/mol and 142.78 kJ/mol in granular sludge, respectively. Granular sludge exhibited better thermal stability but lower devolatilisation activation energy than flocculent sludge, which could be attributed by enriched alkali and alkaline metals during granulation. Master plots of experimental data sets suggested that the decomposition of all organic pseudo-components of flocculent sludge followed the nth-order mechanism while the pyrolytic mechanism of the first organic fraction in granular sludge coincided with random nucleation and nuclei growth. By investigating the pyrolytic behaviour, this study sheds light on the composition of granular sludge and the impact of sludge components on granular sludge pyrolysis, and lays the foundation for the treatment of waste granular sludge with potential for resource and energy recovery in the near future.

Resource recovery potentials by landfill mining and reclamation in South Korea

In the existing paradigm for waste management, landfills are the final disposal site for waste with no control over the waste being sent to the sites. However, the expanding number of landfills that are at the end of their lifespans and the increasing amount of waste disposed of to landfills have presented a growing need for a shift in this paradigm, which can be achieved by the active promotion of landfill mining and resource recovery. In this study, we analyze the landfill resource recovery potentials to understand the effects on landfill lifespan extension, reduction in landfill disposal rate, energy saving, and reduction in greenhouse gas (GHG) emissions. Simulations based on material flow analysis were conducted on existing landfills, which were categorized into four different types based on their remaining capacities and availability of nearby incineration or SRF facilities. The resource recovery potentials, GHG reduction effect, and energy saving effect were higher for Type 2-1 and Type 2-2 landfills with higher ratios of combustible waste. The landfill lifespan extension effect was the highest for Type 2-2 landfill which receives a relatively smaller amount of waste than the other landfills. The reduction in landfill disposal rate was highest for Type 3, which does not have an incinerator or SRF facilities nearby. On the other hand, the overall effects, including the effect on reducing the landfill disposal rate, are the lowest for Type 1 because the chosen landfill only covers a significantly small proportion of the total waste generated in the city compared to the other landfills. The findings of this study suggest that appropriate landfill mining and reclamation operations are integral to prolonging the lifespans of existing landfills and present insights for building future landfill management strategies.

Sustainable waste management through synergistic utilisation of commercial and domestic organic waste for efficient resource recovery and valorisation in the UK

The UK is facing tremendous challenges in tackling food waste diversion from landfill. Whilst much effort has been made to prevent food waste, there is still a lack of attention and strategic approach in dealing with resource recovery and valorisation of food waste. This paper presents a systematic framework for sustainable organic waste management and valorisation in the UK through (i) review of current policy framework; (ii) analysis of resource recovery potential from food waste at national, community and organisational levels; (iii) proposition of alternative waste management strategies; and (iv) examination of challenges and opportunities with respect to economic, environment and social dimensions of sustainability of waste management strategies. The paper explores valorisation of source-segregated food waste and mixed waste from the supermarket and households into electricity and transportation fuels, through partially and completely decentralised configurations using anaerobic digestion and gasification technologies. This study demonstrates a potential for reducing the cost of electricity and greenhouse gas emissions of one supermarket store by 12% when adopting partially decentralised food waste anaerobic digestion strategy, and full substitution of fossil fuel based electricity with net surplus renewable electricity generation through complete decentralisation of mixed waste gasification. Therefore, a more integrated, circular and advanced technological approach in waste management should be undertaken as it can lead to a wider range of socio-economic and environmental advantages to the local community, highly essential in the UK.

Non-woven fabric activated carbon produced from fibrous waste biomass for sulphur dioxide control

Waste fibrous biomass (flax) has been processed using non-woven textile techniques to produce a fibrous fabric material. The biomass fabric was then processed to produce activated carbons which retained their structure and flexibility. The carbons produced in a range of process conditions possessed a range of different surface areas and porosities. The activated carbons produced by chemical activation at different temperatures had high surface areas, ranging from 126 m2 g−1 for the activated carbon produced at 450 ºC to 1177 m2 g−1 produced at 800 °C activation temperature. At increased hold times at 800 °C the surface areas increased further, for example reaching 1656 m2 g−1 at 2 h hold time. The activated carbons were found to be very microporous, containing very small micropores. The produced activated carbons were then investigated in terms of the removal of sulphur dioxide in a bench scale continuous flow reactor. The SO2 adsorption results showed that for the waste biomass fibre carbons, uptake of SO2 from the gas stream was found to be dependent on the degree of activation. As the micropore volume and surface area of the samples increased, the SO2 adsorption capacity also increased, observing a linear relationship. The adsorption of SO2 by the waste derived activated carbons was significantly higher when compared to commercially obtained activated carbons. This appeared to be related to the pore size distribution of the samples, with the waste biomass activated carbons possessing a greater number of ultra-micropores than the commercial samples. Increase in the temperature of the activated carbon bed led to a marked decrease in the adsorption of SO2. Uptake of SO2 was also shown to be dependent on the concentration of the SO2 inlet feed gas, where higher SO2 concentrations led to enhanced uptake. The advantages of using textile processing techniques to produce a non-woven fabric activated carbon enabling different forms to be produced related to the end-use application has great potential for resource recovery.

Effects of light-dark cycles on photosynthetic bacteria wastewater treatment and valuable substances production

Photosynthetic bacteria (PSB) wastewater treatment is a novel method with great potential for resource recovery. Light-dark cycle is important for photosynthetic microorganisms, but its impact on PSB wastewater treatment is still unclear. This study evaluated the effects of four light-dark cycles on PSB biomass, valuable substances production, and pollutant removal. Results indicate that the highest biomass concentration was obtained under 24 h light/24 h dark cycle. The highest concentrations of protein and coenzyme Q10 were obtained under 3 h light/3h dark cycle (826.73 and 88.8 mg/g, respectively). Pigment production were stable under all light-dark cycles tested. Light-dark cycles had little effect on COD and TP removal, while 24 h light/24 h dark cycle resulted in the highest NH3-N removal. ATP and RuBisCO concentrations followed similar trends under different light-dark cycles. These results revealed that PSB could provide more biomass and valuable substances with given energy by changing light-dark cycles.