Sanitation in the Circular Economy: Transformation to a Commercially Valuable, Self-sustaining, Biological System

In 2016 the Toilet Board Coalition ran a Feasibility Study to explore the potential role of Sanitation in the Circular Economy. The following questions were at the centre of our inquiry:- Are there products or materials of value being upcycled from toilet resources?- Are there scalable business models to deliver sustainable supply of these products to the market?- Is there commercial interest and demand from large industrial operations to become buyers into the system? This paper presents the findings of our study in the form of a thought piece on the topic of sanitation in the Circular Economy. Our intent is to present a number of business opportunity spaces, where we believe that value has been left on the table and customer needs unmet, which we recommend are to be explored further in the decade ahead.

Challenges of a feasible route towards sustainability in environmental protection

Anaerobic processes for treatment of low and high strength wastewaters and solid wastes constitute the core method in the natural biological mineralization (NBM) treatment concept. When adequately combined with the complementary NBM-systems and modern clean water saving practices in wastewater collection and transport, they represent a feasible route to sustainable environmental protection (EPsus), in essence even towards a more sustainable society. Despite the development and implementation of modern high rate Anaerobic Wastewater Treatment (AnWT-) systems and complementary innovative NBM-processes, the considerable progress made since the seventies in fundamental insights in microbiology, biochemistry and process technology, still numerous challenging improvements in the NBM-field can be realized. This contribution is mainly based on the insights attained from wide ranging literature evaluations and the results of experimental research conducted by numerous PhD students who participated in our group over the last four decades. An attempt is made here to identify major facets on which an improved insight can, and consequently should, be obtained in order to accomplish more optimal operation and design of various types of Anaerobic Degradation (AnDeg-) processes

MODEL DEVELOPMENT AND SYSTEM OPTIMIZATION TO MINIMIZE GREENHOUSE GAS EMISSIONS FROM WASTEWATER TREATMENT PLANTS

As greenhouse gas emissions (GHG) reduction has drawn considerable attention, various methods have been established to estimate greenhouse gas emissions from wastewater treatment plants (WWTPs). In order to establish a design and operational strategy for GHG mitigation, accurate estimates are essential. However, the existing approaches (e.g. the IPCC protocol and national greenhouse gas inventories) do not cover emissions from all sources in WWTPs and are not sufficient to predict facility-level emissions. The ultimate goal of this research was to improve the quantification of GHG emissions from WWTPs. This was accomplished by creating a new mathematical model based on an existing activated sludge model. The first part of the research proposed a stepwise methodology using elemental balances in order to derive stoichiometry for state variables used in a mass balance based whole-plant wastewater treatment plant model. The two main advantages of the elemental balance method are the inclusion of carbon dioxide (CO2) into the existing model with no mass loss and ease of tracking elemental pathways. The second part of the research developed an integrated model that includes (1) a direct emission model for onsite emissions from treatment processes and (2) an indirect emission model for offsite emissions caused by plant operation. A sensitivity analysis of the proposed model was conducted to identify key input parameters. An uncertainty analysis was also carried out using a Monte Carlo simulation, which provided an estimate of the potential variability in GHG estimations. Finally, in the third part, the research identified an optimal operational strategy that resulted in minimizing operating costs and GHG emission, while simultaneously treating the wastewater at better levels. To do this, an integrated performance index (IPI) was proposed to combine the three criteria. The IPI was then incorporated into an optimization algorithm. The results obtained in this research demonstrated that the variation of GHG emissions is significant across the range of practical operational conditions. With system optimization, however, WWTPs have the potential to reduce GHG emissions without raising operating costs or reducing effluent quality. Further research should include a mechanistic examination of processes that produce methane (CH4) in the wastewater treatment stream and nitrous oxide (N2O) in the sludge treatment stream

Life cycle assessment of biowaste and green waste composting systems : A review of applications and implementation challenges

Altres ajuts: acords transformatius de la UABComposting is one of the most widely applied methods for recycling organic waste. This process has been proposed as one option that facilitates the reincorporation of materials into the production cycle. However, composting also generates environmental impacts. Life Cycle Assessment (LCA) is the most common approach to evaluate the environmental impacts of a process at different system stages. Nevertheless, applying LCA in composting facilities is challenging due to the extensive information required, the lack of standardization on the initial assumptions, the definition of system boundaries, and the high diversity of existing composting technologies. This paper systematically reviews LCA studies in biowaste and/or green waste composting. The study highlights the challenges that should be met in order to improving the application of LCA to evaluate the environmental impacts of this type or waste treatment strategy. The review protocol used identified 456 papers published between 2010 and 2022. After the screening, 56 papers were selected, read, and thoroughly analyzed. The results show that: i) about 68% of the studies aimed to compare composting with other solid waste management options; ii) there was a wide diversity among the impact categories considered, which predominantly included climate change and ozone depletion; iii) there was no consensus on the functional unit or the system boundaries; iv) the main gaseous emissions studied were ammonia, methane, and nitrogen oxide, which were generally determined by emission factors; v) the avoided environmental impacts associated with the end-product quality and its application as an organic amendment or soil improver were ignored. This work demonstrates the complexity of conducting credible and valid composting LCA studies and proposes seven recommendations for improving the application of this assessment methodology to analyze this waste management alternative

Life-cycle Cost Analysis of Nutrient Reduction Technologies Employed in Municipal Wastewater Treatment

Eutrophication presents a serious threat to America\u27s aquatic ecosystems, negatively impacting both the aquatic life and the communities dependent on these bodies of water. Reducing nutrient inflow of nitrogen and phosphorus into waterways from point and non-point sources is critical in reversing the environmental degradation caused by eutrophication. Municipal wastewater treatment plants are one of the primary point sources of nutrient-rich effluent, and as such, implementing nutrient reduction strategies within the treatment process is an impactful step towards mitigating eutrophication. Grey infrastructure technologies that use mechanical or chemical treatment have historically been used for wastewater nutrient reduction. However, constructed wetlands have also been implemented for wastewater nutrient reduction. These systems mimic the biological and chemical processes that occur in natural wetlands to remove nutrients but in a more controlled environment. A life-cycle cost analysis is conducted to analyze differences between the total life cycle costs of constructed wetland systems and grey infrastructure improvements for nutrient removal from municipal wastewater treatment facilities. Furthermore, this paper evaluates whether the inclusion of ecosystem services generated by constructed wetlands significantly reduces their life-cycle costs. The results of this study suggest that CW systems are more cost-effective than grey infrastructure technologies for nutrient reduction when ecosystem services are included in the analysis. This study lays the groundwork for future research on the inclusion of ecosystem services into future life-cycle cost analysis for nutrient reduction and cost analyses for constructed wetland systems

Life-cycle Cost Analysis of Nutrient Reduction Technologies Employed in Municipal Wastewater Treatment

Eutrophication presents a serious threat to America\u27s aquatic ecosystems, negatively impacting both the aquatic life and the communities dependent on these bodies of water. Reducing nutrient inflow of nitrogen and phosphorus into waterways from point and non-point sources is critical in reversing the environmental degradation caused by eutrophication. Municipal wastewater treatment plants are one of the primary point sources of nutrient-rich effluent, and as such, implementing nutrient reduction strategies within the treatment process is an impactful step towards mitigating eutrophication. Grey infrastructure technologies that use mechanical or chemical treatment have historically been used for wastewater nutrient reduction. However, constructed wetlands have also been implemented for wastewater nutrient reduction. These systems mimic the biological and chemical processes that occur in natural wetlands to remove nutrients but in a more controlled environment. A life-cycle cost analysis is conducted to analyze differences between the total life cycle costs of constructed wetland systems and grey infrastructure improvements for nutrient removal from municipal wastewater treatment facilities. Furthermore, this paper evaluates whether the inclusion of ecosystem services generated by constructed wetlands significantly reduces their life-cycle costs. The results of this study suggest that CW systems are more cost-effective than grey infrastructure technologies for nutrient reduction when ecosystem services are included in the analysis. This study lays the groundwork for future research on the inclusion of ecosystem services into future life-cycle cost analysis for nutrient reduction and cost analyses for constructed wetland systems

Pathways to Water Sector Decarbonization, Carbon Capture and Utilization

The water sector is in the middle of a paradigm shift from focusing on treatment and meeting discharge permit limits to integrated operation that also enables a circular water economy via water reuse, resource recovery, and system level planning and operation. While the sector has gone through different stages of such revolution, from improving energy efficiency to recovering renewable energy and resources, when it comes to the next step of achieving carbon neutrality or negative emission, it falls behind other infrastructure sectors such as energy and transportation. The water sector carries tremendous potential to decarbonize, from technological advancements, to operational optimization, to policy and behavioural changes. This book aims to fill an important gap for different stakeholders to gain knowledge and skills in this area and equip the water community to further decarbonize the industry and build a carbon-free society and economy. The book goes beyond technology overviews, rather it aims to provide a system level blueprint for decarbonization. It can be a reference book and textbook for graduate students, researchers, practitioners, consultants and policy makers, and it will provide practical guidance for stakeholders to analyse and implement decarbonization measures in their professions

Integrating Algaculture into Small Wastewater Treatment Plants: Process Flow Options and Life Cycle Impacts

Algaculture has the potential to be a sustainable option for nutrient removal at wastewater treatment plants. The purpose of this study was to compare the environmental impacts of three likely algaculture integration strategies to a conventional nutrient removal strategy. Process modeling was used to determine life cycle inventory data and a comparative life cycle assessment was used to determine environmental impacts. Treatment scenarios included a base case treatment plant without nutrient removal, a plant with conventional nutrient removal, and three other cases with algal unit processes placed at the head of the plant, in a side stream, and at the end of the plant, respectively. Impact categories included eutrophication, global warming, ecotoxicity, and primary energy demand. Integrating algaculture prior to activated sludge proved to be most beneficial of the scenarios considered for all impact categories; however, this scenario would also require primary sedimentation and impacts of that unit process should be considered for implementation of such a system

Compost and digestate: sustainability, benefits, impacts for the environment and for plant production

This proceedings volume contains the papers presented at the CODIS 2008 congress held on 27 - 29 February 2008 in Solothurn (Switzerland).The composting and digestion of biogenic waste materials and the subsequent application of compost and digestate to soil contributes to nutrient recycling and renewable energy production. Moreover, compost and digestate can improve soil fertility and suppress plant diseases. On the other hand, compost and digestate may also contain a variety of pollutants hazardous to soil, such as heavy metals and organic contaminants.Compost and digestate have been thoroughly investigated in the framework of two associated projects entitled Organic Pollutants in Compost and Digestate in Switzerland and Effects of Composts and Digestate on the Environment, Soil Fertility and Plant Health. These projects yielded new insights into the properties of compost and digestate, mainly with regard to biological parameters and the occurrence of both classic and emerging organic pollutants.The CODIS 2008 congress was the final event of these two projects