Assessing the environmental impact of resource recovery from dairy manure.

Manure management is a major contributor to environmental impacts from large-scale dairy production. In this study, technologies for recovering energy, nutrients, and water from dairy manure were evaluated using life cycle assessment (LCA) and compared to conventional practices on California dairy farms. Six scenarios were evaluated: conventional manure management practices, anaerobic digestion (AD) for biogas recovery, and four scenarios for nutrients, energy, and water integrated recovery, called NEWIR. The NEWIR system consists of hydrothermal carbonization (HTC) for energy recovery via hydrochar, algae cultivation in the HTC aqueous product for nutrient recovery and production of protein-rich cattle feed, and water recovery from algae pond effluent via membrane distillation. Four NEWIR scenarios were evaluated, each with a different species of algae. Based on the results of the LCA, AD improves GHG emissions relative to conventional practices by 82%, but has similar eutrophication impacts, posing similar concerns for nutrient management as current practices. Results for the NEWIR system are highly dependent on the algae species used. Three of the four species evaluated (Chlamydomonas reinhardtii, Chlorella vulgaris, and Scenedesmus obliquus) improve GHG emissions by 420-500 kg CO2-eq. per functional unit, while net water consumption is increased by approximately 75% over AD and conventional practices Spirulina maxima requires more water and chemical inputs for cultivation than the other species, resulting in higher water use (21 times higher than baseline), though GHG emissions are still reduced by 85 kg CO2-eq. per functional unit relative to conventional practices. All NEWIR scenarios improve eutrophication impacts relative to AD and conventional practices by 16-46% for marine eutrophication and 18-99% for freshwater eutrophication, depending on the algae species used. The results suggest integrated resource recovery through NEWIR is a promising treatment method for manure to mitigate GHG emissions and improve nutrient management on large-scale farms. In addition, carbon and nutrient trading policies are discussed in relation to resource recovery technologies and their potential to incentivize producers to recover products from dairy manure.

Improving Life Cycle Economic and Environmental Sustainability of Animal Manure Management in Marginalized Farming Communities Through Resource Recovery.

A growing world population with increasing levels of food consumption will lead to more dairy and swine production and increasing amount of manure that requires treatment. Discharge of excessive nutrients and carbon in untreated animal manure can lead to greenhouse gas emissions and eutrophication concerns, and treatment efforts can be expensive for small scale farmers in marginalized communities. The overall goal of this study was to determine the environmental and economic sustainability of four animal manure management scenarios in Costa Rica: (1) no treatment, (2) biodigesters, (3) biodigesters and struvite precipitation, and (4) biodigesters, struvite precipitation, and lagoons. Life cycle assessment was used to assess the carbon footprint and eutrophication potential, whereas life cycle cost analysis was used to evaluate the equivalent uniform annual worth over the construction and operation and maintenance life stages. Recovery of biogas as a cooking fuel and recovery of nutrients from the struvite reactor reduced the carbon footprint, leading to carbon offsets of up to 2,500 kg CO2 eq/year. Offsets were primarily due to avoiding methane emissions during energy recovery. Eutrophication potential decreased as resource recovery processes were integrated, primarily due to improved removal of phosphorus in effluent waters. Resource recovery efforts led to equivalent uniform annual benefits of $825 to $1,056/year, which could provide a helpful revenue source for lower-income farmers. This research can provide clarity on how small-scale farmers in marginalized settings can utilize resource recovery technologies to better manage animal manure, while improving economic and environmental sustainability outcomes.

A new framework for small drinking water plant sustainability support and decision-making.

Public drinking water system decisions about treatment processes are becoming more challenging, especially as regulations become more stringent and source water quality degrades. For small systems that serve <10,000 people, treatment decisions are particularly difficult due to limited resources and because they do not currently have resources to help them make informed and sustainable decisions using environmental, social, and economic criteria. Therefore, a user-friendly sustainability assessment framework, which compares treatment processes relevant to a wide variety of small drinking water systems, was constructed. In summary, the framework uses life cycle assessment and multiple-criteria decision analysis to comprehensively evaluate twelve decision criteria, developed specific to small drinking water systems; the framework then uses an aggregation approach to identify and navigate multiple trade-offs and make a final recommendation based on stakeholder values. Four hypothetical scenarios were examined to show the framework's applicability to diverse small systems, ability to help stakeholders navigate trade-offs, and engineering relevance. The framework is universal in its capacity to evaluate systems with different design parameters, source waters, treatment criteria, and stakeholder preferences.

Sustainability metrics for assessing water resource recovery facilities of the future.

The recovery of water, energy, and nutrients from water resource recovery facilities (WRRFs) is needed to address significant global challenges, such as increasing water demand and decreasing availability of nonrenewable resources. To meet these challenges, innovative technological developments must lead to increased adoption of water and resource recovery processes, while addressing stakeholder needs (e.g., innovators, practitioners, regulators). A test bed network of over 90 partner facilities within the United States and abroad will help accelerate innovation and widespread adoption of novel processes through multiscale testing and demonstration of technologies. In this paper, we define a common set of environmental, economic, technical, and social performance metrics for innovative technologies, that will meet the needs of multiple stakeholders in the decision-making process. These triple bottom line performance metrics can be used to track the sustainability of technologies in a consistent and transparent manner, while aiding the decision-making process for WRRFs. PRACTITIONER POINTS: The Facilities Accelerating Science and Technology (FAST) Water Network includes over 90 test bed facilities dedicated to accelerating innovation and adoption of water energy, and nutrient recovery systems. A common set of environmental, economic, technical, and social performance metrics should be measured and reported when a new technology is evaluated in the FAST Water Network. Performance metrics can aid sustainable decision-making at WRRF, while meeting the needs of multiple stakeholders.

Life cycle environmental and economic implications of small drinking water system upgrades to reduce disinfection byproducts.

Many of the small drinking water systems in the US that utilize simple filtration and chlorine disinfection or chlorine disinfection alone are facing disinfection byproduct (DBP) noncompliance issues, which need immediate upgrades. In this study, four potential upgrade scenarios, namely the GAC, ozone, UV30, and UV186 scenarios, were designed for a typical small drinking water systems and compared in terms of embodied energy, carbon footprint, and life cycle cost. These scenarios are designed to either reduce the amount of DBP precursors using granular activated carbon filtration (the GAC scenario) or ozonation (the ozone scenario), or replace the chlorine disinfection with the UV disinfection at different intensities followed by chloramination (the UV30 and UV186 scenarios). The UV30 scenario was found to have the lowest embodied energy (417 GJ/year) and life cycle cost ($0.25 million US dollars), while the GAC scenario has the lowest carbon footprint (21 Mg CO2e/year). The UV186 scenario consistently presents the highest environmental and economic impacts. The major contributors of the economic and environmental impacts of individual scenarios also differ. Energy and/or material consumptions during the operation phase dominate the environmental impacts of the four scenarios, while the infrastructure investments have a noticeable contribution to the economic costs. The results are sensitive to changes in water quality. An increase of raw water quality, i.e., an increase in organic precursor content, could potentially result in the ozone scenario being the least energy intensive scenario, while a decrease of water quality could greatly reduce the overall competitiveness of the GAC scenario.

Accelerating Innovation that Enhances Resource Recovery in the Wastewater Sector: Advancing a National Testbed Network.

This Feature examines significant challenges and opportunities to spur innovation and accelerate adoption of reliable technologies that enhance integrated resource recovery in the wastewater sector through the creation of a national testbed network. The network is a virtual entity that connects appropriate physical testing facilities, and other components needed for a testbed network, with researchers, investors, technology providers, utilities, regulators, and other stakeholders to accelerate the adoption of innovative technologies and processes that are needed for the water resource recovery facility of the future. Here we summarize and extract key issues and developments, to provide a strategy for the wastewater sector to accelerate a path forward that leads to new sustainable water infrastructures.

Impact of sludge layer geometry on the hydraulic performance of a waste stabilization pond.

Improving the hydraulic performance of waste stabilization ponds (WSPs) is an important management strategy to not only ensure protection of public health and the environment, but also to maximize the potential reuse of valuable resources found in the treated effluent. To reuse effluent from WSPs, a better understanding of the factors that impact the hydraulic performance of the system is needed. One major factor determining the hydraulic performance of a WSP is sludge accumulation, which alters the volume of the pond. In this study, computational fluid dynamics (CFD) analysis was applied to investigate the impact of sludge layer geometry on hydraulic performance of a facultative pond, typically used in many small communities throughout the developing world. Four waste stabilization pond cases with different sludge volumes and distributions were investigated. Results indicate that sludge distribution and volume have a significant impact on wastewater treatment efficiency and capacity. Although treatment capacity is reduced with accumulation of sludge, the latter may induce a baffling effect which causes the flow to behave closer to that of plug flow reactor and thus increase treatment efficiency. In addition to sludge accumulation and distribution, the impact of water surface level is also investigated through two additional cases. Findings show that an increase in water level while keeping a constant flow rate can result in a significant decrease in the hydraulic performance by reducing the sludge baffling effect, suggesting a careful monitoring of sludge accumulation and water surface level in WSP systems.

How Does Scale of Implementation Impact the Environmental Sustainability of Wastewater Treatment Integrated with Resource Recovery?

Energy and resource consumptions required to treat and transport wastewater have led to efforts to improve the environmental sustainability of wastewater treatment plants (WWTPs). Resource recovery can reduce the environmental impact of these systems; however, limited research has considered how the scale of implementation impacts the sustainability of WWTPs integrated with resource recovery. Accordingly, this research uses life cycle assessment (LCA) to evaluate how the scale of implementation impacts the environmental sustainability of wastewater treatment integrated with water reuse, energy recovery, and nutrient recycling. Three systems were selected: a septic tank with aerobic treatment at the household scale, an advanced water reclamation facility at the community scale, and an advanced water reclamation facility at the city scale. Three sustainability indicators were considered: embodied energy, carbon footprint, and eutrophication potential. This study determined that as with economies of scale, there are benefits to centralization of WWTPs with resource recovery in terms of embodied energy and carbon footprint; however, the community scale was shown to have the lowest eutrophication potential. Additionally, technology selection, nutrient control practices, system layout, and topographical conditions may have a larger impact on environmental sustainability than the implementation scale in some cases.

Quantifying benefits of resource recovery from sanitation provision in a developing world setting.

Despite concerns of sanitation provision, water scarcity, climate change, and resource depletion, limited research has been conducted to assess the environmental impact of wastewater treatment and resource recovery strategies to improve access to sanitation and resource utilization in developing world settings. Accordingly, the goal of this study is to evaluate the potential benefits of mitigating the environmental impact of two small community-managed wastewater treatment systems in rural Bolivia using resource recovery (i.e., water reuse and energy recovery). Life Cycle Assessment (LCA) is used to estimate the embodied energy, carbon footprint, and eutrophication potential of these systems under existing and resource recovery conditions. Two distinct technologies are analyzed: (1) an upflow anaerobic sludge blanket reactor (UASB) followed by two maturation ponds in series (UASB-Pond system) and (2) a facultative pond followed by two maturation ponds in series (3-Pond system). For the existing systems, bathroom and collection infrastructure had a higher energy intensity than the treatment processes, whereas direct methane emissions from treatment were the primary contributors to the carbon footprint. Taking advantage of reclaimed water was found to greatly reduce the eutrophication potential for both systems, in which the reduction increases proportionally to the percentage of water that is reclaimed. Energy recovery from the UASB-Pond system provided a 19% reduction in embodied energy and a 57% reduction in carbon footprint. Combining water reuse and energy recovery for the UASB-Pond system reduced the eutrophication potential, embodied energy and carbon footprint simultaneously. This highlights the benefits of integrated resource recovery.