To limit effluent impacts on eutrophication in receiving waterbodies, a small community water resource recovery facility (WRRF) upgraded its conventional activated sludge treatment process for biological nutrient removal, and considered enhanced primary settling and anaerobic digestion (AD) with co-digestion of high strength organic waste (HSOW). The community initiated the resource recovery hub concept with the intention of converting an energy-consuming wastewater treatment plant into a facility that generates energy and nutrients and reuses water. We applied life cycle assessment and life cycle cost assessment to evaluate the net impact of the potential conversion. The upgraded WRRF reduced eutrophication impacts by 40% compared to the legacy system. Other environmental impacts such as global climate change potential (GCCP) and cumulative energy demand (CED) were strongly affected by AD and composting assumptions. The scenario analysis showed that HSOW co-digestion with energy recovery can lead to reductions in GCCP and CED of 7% and 108%, respectively, for the upgraded WRRF (high feedstock-base AD performance scenarios) relative to the legacy system. The cost analysis showed that using the full digester capacity and achieving high digester performance can reduce the life cycle cost of WRRF upgrades by 15% over a 30-year period. deteriorating water quality in water bodies due to eutrophication and pollution from point-sources such as effluents from wastewater treatment facilities. In response, the U.S. Environmental Protection Agency (U.S. EPA) has implemented more stringent effluent quality standards [2]. In addition, much of the wastewater treatment infrastructure is in dire need of improvement due to age, wear, and tear. In 2013, the American Society of Civil Engineers' Infrastructure Report Card assigned both drinking water and wastewater infrastructures a grade of D + , indicating a considerable backlog of overdue maintenance and a pressing need for modernization [3]. With a growing population facing increased regulatory requirements, resource constraints, and financial challenges, communities are seeking more comprehensive and sustainable solutions to address multiple environmental challenges and maximize the recovery of water, energy, nutrients, and materials [1,4,5]. Municipal wastewater and other high strength organic wastes (HSOW) generated in cities are now regarded as a resource for water, energy, and nutrients [6-10].However, the environmental sustainability of wastewater systems goes beyond the treatment plants. It has been argued that many impacts occur at a larger watershed level or along upstream supply chains during energy, chemical, and material production [11,12]. These complex water issues are inherently intertwined and cannot be solved by traditional siloed water management approaches [1]. It is necessary to apply system-based tools or metrics and integrated assessment frameworks such as life cycle assessment (LCA) and life cycle cost assessment (LCCA) to measure trade-offs and develop op...
The paper focuses on the improvements to engineered features of a passive technology that has been used for remediation of acid rock drainage (ARD). This passive remedial technology, a sulfate-reducing bacteria (SRB) bioreactor, takes advantage of the ability of SRB that, if supplied with a source of organic carbon, can increase pH and alkalinity of the water and immobilize metals by precipitating them as metal sulfides or hydroxides.The remoteness of ARD sites and their abundance require that the design of an SRB bioreactor be simple and inexpensive. Therefore, bioreactors need to be designed to a size that allows for transportation using primitive roads. To satisfy these requirements a design for a modular treatment system was developed using reactive cartridges (RC) that are prefabricated as 2.44-meter diameter vessels. The RC has been designed so it supports the prime functional aspects of a bioreactor such as high permeability, ample supply of organic carbon, ability to maintain anaerobic conditions, and capacity to accumulate precipitated metals and means for their periodical removal, as needed. In addition, the configuration of the RC allows for an easy replacement of the organic carbon. The RCs can be transported to an ARD site and assembled into a treatment system with a number of modules as required by the ARD flow rate and the metals load. A bioreactor system consisting of four RCs will be installed at an abandoned mine site with ARD of pH 5 or lower and a significant load of metals. The process of site selection is in progress.The RC design was developed by the Mine Waste Technology Program (MWTP) at MSE Technology Applications (MSE), Butte, Montana, USA.
Pulsed limestone bed treatment is a new technology for the processing of acid mine drainage that utilizes limestone in fluidized bed reactors for an economical method of neutralizing acidity, adding alkalinity, and removing metal contaminants from mining impacted waters. The technology was developed by the U.S. Geological Survey, at the Leetown Science Center in Kearneysville, West Virginia. Previous demonstrations of this technology have taken place at coal mining sites in the Appalachian region. In this demonstration project, funded by the Mine Waste Technology Program of EPA, the Pulsed Limestone Bed (PLB) technology is being demonstrated at the Argo Tunnel Water Treatment Facility, which currently treats metal mining impacted waters flowing into Clear Creek. A 230 liter per minute pilot treatment system was installed in a moving van trailer and transported to the site in summer of 2004. Untreated water at the Argo site typically contains about 600 mg/L acidity (as CaCO 3), due to the presence of hydrolysable metals including iron, aluminum, copper, zinc and manganese. Shakedown tests of the system were conducted by project cooperators from the Colorado School of Mines, and demonstrated an increase in pH from 3.0 to 7.0, nearly complete removal of iron and aluminum and an effluent alkalinity of about 100 mg/L as CaCO 3. Post-treatment of the process effluent was required for removal of Mn and Zn, but test results indicated a decrease in reagent costs, as well as decreased sludge volume, due to the replacement of lime or sodium hydroxide by limestone as the neutralization agent. Complete process testing is scheduled for summer 2005.
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