Operation Problems
Operation Problems
(OP)
Hi Eng's:
One of some small Sewage Treatment Plants I am responsible for, features a strange performance over the last weeks. It's a small extended airation unit for a Hotel-Lodge. The capacity is enough and it ran well for years. 3 Months ago they had to relocate the unit and for new commissioning we inoculated the plant with healthy sludge from a similiar plant. Since that it never worked well again. The sludge is black and odorous (septic smell), oxygen < 1 mg/l, pH 9.5 - the bugs are obviously dead. There was never any different influent than before (I've still sent a sample to a lab for toxicity tests). I turned the airation to full but can't really explain the happenings. Anybody has an idea?
One of some small Sewage Treatment Plants I am responsible for, features a strange performance over the last weeks. It's a small extended airation unit for a Hotel-Lodge. The capacity is enough and it ran well for years. 3 Months ago they had to relocate the unit and for new commissioning we inoculated the plant with healthy sludge from a similiar plant. Since that it never worked well again. The sludge is black and odorous (septic smell), oxygen < 1 mg/l, pH 9.5 - the bugs are obviously dead. There was never any different influent than before (I've still sent a sample to a lab for toxicity tests). I turned the airation to full but can't really explain the happenings. Anybody has an idea?





RE: Operation Problems
RE: Operation Problems
RE: Operation Problems
aeration. What is your aeration system. Diffused air or agitation? If diffused air, your aeration grid may be plugged and therefore not supplying enough oxygen.
This can happen after a shutdown because the grid plugs up with dried sludge. If you don't get enough air into the system, anaerobic takes over.
RE: Operation Problems
Bob
RE: Operation Problems
RE: Operation Problems
RE: Operation Problems
BOD can be really crazy in a seasonal environment like that. Occupant loading, cleaning loading, and food prep loading all have impacts and play a role at various times. Like rbcoulter is saying and I am tending to agree, I think you air system is not working too well. On seasonal designs i use a flow meter for air simply because the operators are usually not up on the day to day operation of the system and I wrtite operating instructions for the o and m manual based upon flows during various times of the year. Look for a pressure gauge and see if you can use the blower curves to determine the air output. Dont look at the bubbles it wont tell you a thing in these smaller systems.
What type of system is this? Is it a package system and if so who made it? Maybe that will help us some.
Bob
RE: Operation Problems
RE: Operation Problems
we inspect the plant only once a month - so I do not have enough data to provide monotoring. These are the measured data again:
DO (dis. ox) aeration tank = < 1 mg/l
DO (dis. ox) clarifier ~ 1.5 mg/l
pH aeration tank = 9.5
pH clarifier = 9.5
BOD influent = 588 mg/l
BOD effluent = 277 mg/l
TSS influent = 192 mg/l
TSS effluent = 74 mg/l
P influent = 8.5 mg/l
Settled solids mixed liquor = 100 ml/l
Yes, it is a package plant and the design max flow is ~ 5.5 m^3/day. The actual plant capacity is somewhat lower. The sludge is black and smells septic. The flow graph may vary as usual for a small plant for lodge/restaurant business.