A used water treatment facility in a town treats an average daily influent waste sludge at a mass flowrate of 8000 kg/day. Assume that the sludge in all streams at all stages have a temperature of 30°C,pressure of 1 atm and density of 1000 kg/m3. The treatment process is as follows:1) Thickening centrifuges thicken waste sludge.2) Anaerobic digesters remove organic matter in the thickened sludge.3) Dewatering centrifuges thicken digested sludge.On one particular day, the influent waste sludge into the used water treatment facility was measured tohave a COD of 470 mg/L. Assume a COD consumption of 85%, an universal gas constant of0.08206 atm.L/mol.K and the heating value of methane to be 55 MJ/kg. The biogas produced is thenused to generate electricity.(a) Calculate the maximum volume of biogas produced in one day, assuming a methane content of 70%in the biogas. (2 points)(b) Determine the amount of electricity produced per day in kWh when the conversion efficiency frombiogas to electricity of 45%. (2 points)The allowable COD limit discharged into the waterways is 60 mg/L.(c) Can this effluent be discharged without further treatment? Explain. If no, suggest one way to lowerthe COD in the effluent. (2 points)(d) Name one implication of discharging an effluent that is above the allowable COD limit. (1 point)

(a) The maximum volume of biogas produced in one day can be calculated as follows:

First, we need to calculate the mass of COD consumed per day. The COD of the influent waste sludge is 470 mg/L. The daily mass flowrate of the sludge is 8000 kg, which is equivalent to 8000 m3 (since the density of the sludge is 1000 kg/m3). Therefore, the total COD in the influent sludge is 470 mg/L * 8000 m3 = 3.76 * 10^6 g/day.

Assuming a COD consumption of 85%, the mass of COD consumed per day is 0.85 * 3.76 * 10^6 g/day = 3.196 * 10^6 g/day.

The stoichiometric reaction for the anaerobic digestion of organic matter is:

COD + H2O -> CH4 + CO2

Assuming all the consumed COD is converted to methane, the molar mass of methane (CH4) is 16 g/mol. Therefore, the amount of methane produced per day is (3.196 * 10^6 g/day) / (16 g/mol) = 1.998 * 10^5 mol/day.

The volume of a gas at standard temperature and pressure (STP) can be calculated using the ideal gas law: PV = nRT. At STP (T = 273.15 K, P = 1 atm), the volume of 1 mol of gas is approximately 22.4 L. Therefore, the volume of methane produced per day is 1.998 * 10^5 mol/day * 22.4 L/mol = 4.476 * 10^6 L/day.

Assuming a methane content of 70% in the biogas, the maximum volume of biogas produced in one day is 4.476 * 10^6 L/day / 0.7 = 6.394 * 10^6 L/day.

(b) The amount of electricity produced per day can be calculated as follows:

First, we need to calculate the energy content of the biogas produced per day. The heating value of methane is 55 MJ/kg. Therefore, the energy content of the methane produced per day is 1.998 * 10^5 mol/day * 16 g/mol * 55 MJ/kg = 1.759 * 10^6 MJ/day.

Assuming a conversion efficiency from biogas to electricity of 45%, the energy content of the electricity produced per day is 0.45 * 1.759 * 10^6 MJ/day = 7.916 * 10^5 MJ/day.

Since 1 MJ is equivalent to approximately 0.2778 kWh, the amount of electricity produced per day is 7.916 * 10^5 MJ/day * 0.2778 kWh/MJ = 2.198 * 10^5 kWh/day.

(c) The effluent can not be discharged without further treatment. The COD of the effluent is 15% of the influent COD, which is 0.15 * 470 mg/L = 70.5 mg/L. This is above the allowable COD limit of 60 mg/L. One way to lower the COD in the effluent is to use aerobic digestion, which can further break down the organic matter and reduce the COD.

(d) One implication of discharging an effluent that is above the allowable COD limit is that it can cause water pollution, which can harm aquatic life and affect the quality of the water for human use.