Energy recovery potential in Bangladesh from elevated temperature textile processing wastewater: an analysis of energy recovery, energy economics and reduction in carbon dioxide emission

The textile and readymade garments sector is the main engine of economic growth and the main source of foreign currency and employment. It significantly contributes to the national Gross Domestic Product (GDP). The textile industry is resource-intensive, with heavy reliance on water and energy. Groundwater temperature at 27.33 ± 1.46 o C is the source of the process water and is heated for process use in the textile industry for washing, texturing, and dyeing. Energy is required to achieve the desired elevated temperature for process water. The subsequently generated wastewater released at a high temperature of 40.4 ± 8.7 o C, and its thermal energy is not recovered. Recovered thermal energy is an excellent alternative renewable energy source to natural gas and coal used in the industry to fire its boilers to heat the required process water. In this research program, we did an energy recovery analysis from generated wastewater based on groundwater temperature, discharge wastewater temperature, and discharge flow rate (wastewater treatment plant capacities). We also modeled the potential energy recovery. The results of the model were correlated to fuel consumption, economic savings, and reduction in CO 2 emission based on published databases, industrial surveys, and stakeholder input from international retail companies. The analysis shows that 102 T kWh of energy per annum can be recovered with the savings of 8.6 billion cubic meters of natural gas and 6,87,794 tons of coal, producing a total savings of 1.35 billion USD in energy cost per annum. Reducing the consumption of coal and natural gas will reduce CO 2 emissions by 24.8 million tons per annum, more than 20% of annual CO 2 emissions in Bangladesh and 2.00% of total greenhouse gas emissions attributed to the global textile and apparel industry. Hence, this will contribute immensely to a sustainable transition of textile industries towards a green circular economy.