Regarding the MBR process
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The wastewater treatment plant where I work will be required by the environmental protection agency to keep the COD level of the treated water below 80 mg/l in one year; currently, this level is around 95. The manager has asked us to find a solution to this problem, and there will be a salary increase if we succeed. - k% ]- J5 }) B: W1 u# {' N The current process for papermaking wastewater is as follows (COD values in parentheses): inflow well — equalization tank (4500) — cooling tower — mixing tank 1 — primary sedimentation tank (2500) — MBBR reactor (1100) — AST — secondary sedimentation tank (130) — mixing tank 2 — tertiary sedimentation tank (100) — discharge (95)% t5 z- ?1 ]. ]; o" R My suggestion is to add two more MBBR reactors in series between the primary sedimentation tank and the MBBR reactor; I wonder if anyone has used this series-connected MBBR process? At present, the removal efficiency of our MBBR tanks is around 50%–60%, with a retention time of 6 hours; this varies depending on the characteristics of the water coming from the primary sedimentation stage. It’s unknown whether a removal efficiency of over 30% can still be achieved after series connection.
I haven’t used it, but could you try other methods, such as using an air flotation tank or controlling COD by adding chemicals?
Your primary MBBR tank performs very well; the BOD level in its effluent is almost zero. I wonder if you have had it tested. Connecting two more MBBR tanks in series is definitely not feasible. My opinion is that for the first-stage MBBR – hydrolysis-acidification – MBBR process, the hydrolysis time should be extended
Hydrolysis-acidification can be effective before the primary MBBR; the key lies in the residence time for hydrolysis-acidification, so conduct a small-scale test yourself. Or simply hydrolysis acidification + MBBR + hydrolysis acidification + MBBR.