Domestic and industrial wastewater generation and its energy recovery potential in Bangladesh

A sizable amount of wastewater is produced every day. Wastewater treatment is required to safeguard the environment, human health, flora, and aquatic life. However, wastewater treatment is an expensive operation on one hand, but on the other hand, wastewater contains five to ten times the energy needed for treatment in the form of chemical energy. This energy is accessible via biological processes. Wastewater contains potential and kinetic energy in addition to chemical energy, and it can be harnessed to generate hydropower. Any country must have a central inventory of wastewater in order to harvest this energy. To harness renewable energy from wastewater sector, it is necessary to have a central database for wastewater generation with type of wastewater and its parameters. Unfortunately, Bangladesh lacks a reliable inventory of national wastewater generation, composition, and attributes that may be utilized for estimating wastewater's potential energy output. Therefore, the aim of this research is to estimate the annual total domestic and industrial wastewater output in Bangladesh and estimate its energy recovery potentials. To estimate domestic wastewater (DWW) and industrial wastewater (IWW), an income-based estimating technique and industry-based reports/literature, respectively have been used. Few novel technologies, such as up-flow anaerobic sludge blankets (UASB), anaerobic digestion (AD), and micro hydropower plants (MHP), and five scenarios using only half of the total wastewater (DWW & IWW) have been considered for estimating the energy recovery potential of wastewater. For the hydropower evaluation using MHP, the unit total head is assumed, whereas the average chemical oxygen demand (COD) has been considered for the energy potential assessment of the UASB and AD. Techno-economic analysis (TEA) steps have been also discussed. Results indicate that the expected annual output of DWW and IWW is 4874 million m³ /yr. and 452 million m³ /yr., respectively. In terms of energy potential, scenario 2 has the highest (1986 Giga watt-hour equivalent (GWh)/yr.)), followed by scenario 1 (1857 GWh/yr.), scenario 5 (1770 GWh/yr.), scenario 3 (1401 GWh/yr.), and scenario 4 (976 GWh/yr.). This rigorous research will open up new horizons by attracting the attention not only of Bangladeshi researchers, but also of the international community.