Waste source separation including separate treatment of graywater and black water (BW) is gaining popularity as a sustainable integrated water management practice. Along that line, feasibility of anaerobic digestion of BW (toilet water only) from a building occupied with laboratory and office space was investigated using a pilot scale (114 L) upflow anaerobic sludge blanket (UASB) operated at an average temperature of 28 o C. The goal of the reactor was to achieve removal of organics while also generating methane gas for use as a source of energy. Reactor operational OLR varied between 0.21-0.39 kg COD m -3 d -1 and HRT varied from 2.6-4.0 days. Substantial removal of COD (72%), TSS and VSS (95%), and indicator organisms (1.4 log E. coli & 1.1 log fecal coliforms) was achieved over the study period. Methane biogas (61% CH4) produced during digestion provided potential as a source of renewable energy generated through processing the BW.Mounting pressure to conserve water resources has prompted the notion that separation of graywater from wastewater through the use of dual-plumbed systems may enable graywater to be reused to meet nonpotable demands including toilet flushing or irrigation. Graywater reuse has the potential to reduce potable household demand by as much as 20-50% (City of Los Angeles, 1992) and energy requirements for wastewater treatment are greatly reduced. Such water and energy savings have prompted adoption of graywater reuse practices in the United States. In an integrated water management approach where graywater reuse is widely adopted, traditional wastewater treatment practices may not be most appropriate for BW processing. Instead, a more sustainable approach would include anaerobic digestion of BW. This approach not only reduces energy requirements associated with aeration of wastewater, but also has the potential to provide a source of locally available renewable energy through capture of methane biogas.Several research groups have evaluated anaerobic treatment of BW when graywater was treated separately or reused (Masi et al., 2010;Abdel-Shafy, 2009;Zeeman et al., 2008;Elmitwalli et al., 2006;Kujawa-Roeleveld et al., 2006; Luostarinen and Rintala, 2006). For all of these studies, the source of toilet water was from vacuum toilets, except for the study by Luostarinen and Rintala (2006) where synthetic BW was composed, and the systems were operated at ambient temperatures, 10 o C-25 o C, rather than mesophilic temperatures, which are optimal for methane generation. The goal of the studied systems was primarily to achieve acceptable treatment of BW under anaerobic conditions, thus minimizing energy input. Zeeman et al. (2008) demonstrated energy savings by employing this approach compared to traditional methods of wastewater treatment including aeration. Other researchers have operated anaerobic digesters under mesophilic conditions to increase methane generation (van Voorithuizen et al., 2008;Wendland et al., 2007). These researchers demonstrated successful methane generation from BW, with...
As populations continue to increase, the demand for limited water resources has increased. Sustainable water technologies and management methods are critical to our meeting future water quantity and quality demands. Decentralized treatment of blackwater under anaerobic conditions is a wastewater treatment technology being explored for application in new developments. This technology produces methane which can be used as a source of renewable energy. Decentralized anaerobic treatment of blackwater is an attractive alternative to traditional wastewater management because water and energy are conserved and reuse of these resources at a local level is enhanced. A pilot scale anaerobic reactor is under design and construction at the Colorado State University Foothills Campus to treat blackwater (toilet and kitchen sink wastewater) from a building occupied by laboratory and office space. This project is a demonstration study which will answer questions regarding technical feasibility of anaerobic digestion for blackwater treatment. Treatment efficiency and methane production capacity of the anaerobic process will be evaluated with varying design and operation parameters. Biogas produced in the demonstration digester will be assessed for use as a source of alternative energy and treated effluent water will be evaluated for localized reuse in irrigation or for other non-potable uses after wetland treatment.In conjunction with the demonstration study, a decision analysis tool is under development to evaluate technical and economical feasibility of decentralized wastewater treatment (DWWT) systems under user defined development conditions. This tool is expected to greatly assist decision making entities in determining the applicability of DWWT systems for use in new development, where limited practical guidance is available. It is anticipated that the data presented in this study will also contribute to the basis for necessary legislation related to the effectiveness and safety of DWWT and reuse of resources contained within wastewater. Such data is vital to encourage incorporation of sustainable treatment technologies, e.g. DWWT, as aging and failing infrastructure is rapidly becoming in need of replacement and new developments are constructed. 1
A pilot biochemical reactor (BCR) with a design flowrate of 3.8 l/m (1 gpm) has been operating at the Standard Mine Superfund Site for over four years, since August, 2007. The pilot system is entirely passive, using solar energy to power sampling equipment and pumping requirements. BCR treatment relies on biological and chemical reactions within an anaerobic reactor comprised of organic and inorganic materials including woodchips, straw, limestone and bacterial inoculum. The BCR pilot has been treating mining influenced wastewater (MIW) since construction was completed in the summer of 2007. Polishing and aeration of BCR effluent is accomplished in an aerobic polishing cell (APC) containing wetland plants in two of the three cells. The Standard Mine BCR is constructed at an elevation of 3,353 meters (11,000 ft ) above MSL with an average annual snowfall of 10.2 m (400 in ). Limited BCR treatment data from reactors operating under harsh alpine conditions was available before this system was constructed. Operation and monitoring of the BCR has been year round since 2007. Due to the inaccessibility of the site during winter months, an automated sampling system was designed incorporating Teledyne ISCO™ (ISCO) samplers, Hydrolab™ sondes, and a satellite transmission system reporting site operational parameters on a daily basis. In addition to automated sampling, grab samples were taken monthly throughout the 2010/2011 winter using backcountry skiing equipment to access the site.Contaminants of concern (COCs) in the MIW include Cd, Cu, Pb, Mn, and Zn. High metals removal has been observed in BCR effluent since the beginning of operation. In 2009, 2010, and 2011 the average percent removal efficiency for cadmium, Cu, Pb, and Zn exceeded 98%. The pilot study is notable for a long operating period and low analytical laboratory detection limits for metals. BCR treatment of cadmium, Cu, and Pb to less than 5 µg/L has been demonstrated indicating that BCR is capable of approaching or meeting stringent aquatic life water quality standards when operated under harsh high alpine conditions. Both metals and nutrient removal are discussed in relation to receiving stream water quality standards. BCR performance is discussed with additional discussion of performance of BCR effluent polishing by aerobic lagoon.
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