Sustainable Biogas Production Potential from Urban Wastewater in Nepal

Abstract

Abstract-In this paper, we deal with biogas production potential from urban wastewater based on published information. The usual practice of the wastewater handling in urban cities of Nepal is either direct discharge into the rivers and streams or discharge into the septic tanks. In both cases adverse environmental impacts has perceived through directly polluting rivers and streams as well as releasing methane, ammonia and hydrogen sulphide to the atmosphere. In addition to that, the lost opportunity of biogas production along with potential carbon trading can be realized which also help to make the project economically and environmentally sustainable. An estimation of methane (CH 4 ) production and carbon emission reduction from urban wastewater are being done allowing wastewater treatment in an anaerobic baffled reactor (ABR) and upflow anaerobic sludge blanket (UASB). In this regard, average value of some pilot plant experimental results of efficiency of chemical oxygen demand (COD) removal at ABR and UASB from various studies have been taken into consideration. The estimated biogas production potential from urban wastewater is about 22 million m 3 / year equivalent to 14.5MW th, at the same time the carbon dioxide (CO 2 ) emission reduction potential is about 94,500 tons per year. An estimated revenue collection potential through fuel substitution is about 8 million USD per annum while additional benefits from GHG reduction and other improved condition of health, pollution and reuse of wastewater is significantly remarkable.Index Terms-Energy recovery, wastewater, anaerobic baffled reactor, upflow anaerobic sludge blanket, chemical oxygen demand.

A septic tank‐UASB combined system for domestic wastewater treatment: a pilot test

“…A recent study shows that an estimated biogas production potential from urban wastewater in Nepal is about 22 million m 3 /year, equivalent to 14.5 MWh, and a carbon dioxide (CO 2 ) emission reduction potential of about 2460 tons per year (Lohani et al . ). Wastewater anaerobic digestion may, therefore, give direct and indirect environmental and economic benefits.…”

Alternative co-digestion scenarios for efficient fixed-dome reactor biomethanation processes

“…Nevertheless, WW is necessary in order to maintain the TS of the feedstock inside the favorable limits of 80-100 g L -1 (Weiland, 2006). Furthermore, despite the low BMP value, it is crucial for good hygienic conditions of these areas, WW to be treated in the AD reactors in order to reduce the potential contagious diseases such as diarrhea, cholera and tuberculosis (Lohani et al, 2013). Interestingly, BS-Up had a maximum BMP value of 186 NmL CH 4 g -1 VS that was significantly higher than the BMPs of BS-Lo and BS-Mid.…”

A simple anaerobic system for onsite treatment of domestic wastewater

“…A recent study in Nepal shows that an estimated biogas production potential from urban wastewater is about 22 million m 3 /year equivalent to 14.5 MWth, at the sametime, the carbon dioxide (CO 2 ) emission reduction potential is about 2460 tons per year (Lohani et al, 2013). This may directly relate with financial benefits, however, it also has several economic benefits for instance reduction of indoor air pollution, improvement in public health due to improved sanitation and greenhouse gas reduction.…”