You are provided with the following information about a municipal wastewater treatment plant. This plant uses the traditional activated sludge process. There are 150,000 people in the community (their wastewater production is 225 L/day-capita, 0.1 kg BOD5/capita-day). The soluble BOD leaving the primary clarifier is 311 mg/L. The effluent standard is BOD5 = 20 mg/L and TSS = 20 mg/L. Suspended solids were measured as 4300 mg/L in a wastewater sample obtained from the biological reactor, which is 4200 cubic meters in volume. The suspended solids is 15,000 mg/L in the settled secondary sludge, 200 mg/L in plant influent, and 100 mg/L in the primary clarifier effluent. SRT is equal to 4 days. Required:
a. Draw a schematic of the plant and label all provided information on the diagram.
b. What is the plant's aeration basin’s hydraulic residence time (d)?
c. How many kg of secondary dry solids need to be processed daily from the treatment plants?
d. If the sludge wastage rate (Qw) is increased in the plant, will the solids retention time go up, go down, or remain the same?
e. Determine the F/M ratio in units of kg BOD / kg MLVSS-day.