Before the start of the work, the reactor was
seeded with the sludge taken from the secondary
treatment unit of Nestle treatment plant for three days.
The influent was subjected to settling in the effluent
bottle. Due to lack of mechanical return sludge
facility, the settled sludge was daily removed from
the final clarifier in a beaker. The nitrogen (N) and
phosphorus (P) requirements are based on the BOD
of the wastewater, where a BOD: N: P of 100: 5: 1
is considered adequate11
. In this study, the average
value of BOD was 1520 mg/l. Thus the BOD: N: P
for this wastewater came out to be 1520: 310: 3.3 or
100: 20: 0.22. These calculations show that sufficient
amount of N was present in the wastewater. But
the P was 0.22 as against the desirable value of 1.
Hence it was deficient. The deficiency was met by
adding a calculated amount of potassium di-hydrogen
phosphate (KH2PO4) salt.