List of top Water & Wastewater Treatment and Management Questions on Leaching of contaminants into groundwater asked in GATE ES

An adult of 65 kg drinks water for 5 years contaminated with toluene at $0.15$ mg/L. Reference dose (RfD) of toluene $=0.200$ mg/(kg$ . $d). Daily water intake $=2$ L/d. Compute the hazard quotient (HQ) for the adult (rounded to three decimals).

A sewage treatment plant (capacity 10 MLD) treats wastewater using an aerobic biological process. Inlet BOD = 100 mg/L, outlet BOD = 30 mg/L. Microbial yield = 0.5 g VSS/g BOD removed. At 80% plant capacity, the sludge production rate (in kg/day, rounded off to one decimal place) is __________.