Wastewater with High COD, BOD & NH3N

Wastewater with High COD, BOD & NH3N

We are a printing company. Below is our process flow of wastewater treatment

Collection sump - Oil trap - red box (electrocoagulation) - filter press - slow sand filter - Sequencing batch reactor 

Currently we are facing treated wastewater with high COD (400-600mg/l), BOD (97mg/l) and ammoniacal nitrogen (44mg/l).

Our pH value in 
SBR tank is high too (8.3-8.6). Foaming happened during aeration. Before this, we have wasted all sludge from SBR tank and refill it with influent and solution with a microorganism.

Could it be the root cause of the problem? What can I do to solve the