Question

An ındustry discharges 500m^3/day of wastewater containing 12mg/L of cadmium inta a river that serves as a drinking water source for a downstream community. The stream flow is 3500m^3/min. Assuming that the cadmimum acts in conservative fashion (i.e., its disperses in the water and is not removed by precipitation, adsorption, volatilization, biouptake by organisms in the river, or by water treatmen processes) and that the average daily per capita consumption of water is 2L/day , what is the average daily intake of cadmium due to water consumption?

Answer 1

waste water flow rate, Qw = 5rom day = 500x103 Ll day Cadmeum concentration in waste mater, Cow = 12 mg/L flow site of river Lupstream); Q=3500 m/min = 3500x163x60x24 Qo= 5040000 x103 4day Cadmium cocentration in siver (upstream), Co=0 per capita consumption, q = 24 day Liday M mu Cadmeum cocentration atdown stream ( After mixings. Qutor Cmix - Qu Cw + C C - 500x10x12 + 5240000 x103 to 500X163 +5040000 X60% Cmex = 11281 mg/L m4 A verage daily intake cadmium = q Comen - 12 , 2 ung tay = 2.381x10 mg/day