Decentralized Anaerobic Blackwater Management: A Sustainable Development Technology Concept for Urban Water Management

A high‐rate anaerobic biofilm reactor for biomethane recovery from source‐separated blackwater at ambient temperature

“…As shown in Figure 2a, biogas production rate in the anaerobic biofilm reactor increased consistently with the increase in OLRs from 0.77 to 3.01 g COD/L‐d in four stages. The specific methane production rate at OLR of 0.77 g COD/L‐d was 105.3 ml/L‐d, which was considerably higher than that observed from some conventional anaerobic bioreactors investigated for blackwater treatment (31–73 ml/L‐d) (Gallagher & Sharvelle, 2010, 2011; Kujawa‐Roeleveld et al., 2005, 2006; Zamalloa et al., 2013). Due to the increase in OLRs, the steady‐state specific methane production rates increased to 162.5, 211.0, and 304.6 ml/L‐d at OLR of 1.03, 1.68, and 3.01 g COD/L‐d, respectively.…”

“…As shown in Figure 2c, the average methane content in biogas during the entire operation was > 75%. The highest methane content of 83.0% was achieved at OLR of 0.77 g COD/L‐d (Stage 1), which was remarkably higher than that of conventional anaerobic bioreactors for blackwater (62%–78%) (De Graaff et al., 2010; Gallagher & Sharvelle, 2010, 2011; Kujawa‐Roeleveld et al., 2005, 2006; Zamalloa et al., 2013). At OLR of 1.03 g COD/L‐d (Stage 2), methane content slightly decreased to 79.6%.…”

“…configuring a simple anaerobic biofilm reactor amended with carbon fibers can potentially provide a relatively inexpensive treatment method for blackwater. The methane content in biogas was ranged from 75.5% to 83.0%, which was higher than that reported for conventional blackwater digestion systems, such as 61% for a continuously stirred tank reactor (CSTR) (Wendland et al, 2007), 72% for up-flow anaerobic sludge blankets (UASBs) (Gallagher & Sharvelle, 2010, and 70% for UASB-septic tank (UASB-ST) (Luostarinen & Rintala, 2007). The utilization of CO 2 through DIET-based methanogenesis could provide high-quality biogas (Liu, Sun, Zhao, Dang, & Holmes, 2019).…”

“…Domestic wastewater generated from most urban areas around the world is collected and treated in centralized wastewater plants. Increasingly, decentralized wastewater treatment is being considered as a sustainable sanitation concept for urban wastewater management, by separating blackwater and gray water at source (Gallagher & Sharvelle, 2010). Blackwater, which is a mixture of feces, urine, toilet paper, and flush water, accounts for less than 30% of the total volume but contains about 70% organic matter and 80% nutrients of domestic wastewater (Kujawa‐Roeleveld & Zeeman, 2006; Moges, Todt, Janka, Heistad, & Bakke, 2018).…”

Cost-effectiveness of nitrogen mitigation by alternative household wastewater management technologies

“…Our assumptions about volatilization of nitrogen include (1) no nitrogen compounds other than ammonia will volatilize from collected compost or urine during storage, transport, or treatment; (2) ammonia volatilization from stored urine is independent of the time of storage and so can be conceptualized as occurring entirely during the storage phase (not the transport phase); (3) the volatilization of ammonia from stored compost from composting toilets is the same as from stored urine; (4) 100% of volatilized reactive nitrogen compounds will be re-deposited within the watershed (base case); and (5) there is no volatilization of any nitrogen compounds in pressure or vacuum sewers, because these are designed to have no headspace (completely full pipes) and thus there is no opportunity for volatilization. Negligible to no N 2 volatilizes during composting and urine diversion, due to lack of anaerobic conditions needed for denitrification, nor from blackwater digestion (Baek and Pagilla, 2006;Gallagher and Sharvelle, 2010;Lin et al, 2013), thus nitrogen is mitigated in these systems by physical removal from the watershed, which we assume is achieved by truck transportation.…”