Waste water treatment is an essential process for the completed function of a food industry. The policy of Athenian Brewery SA is to ensure that all of its activities are materialized with a friendly way towards the environment. Thus, the best environmental technology is adapted for the proper waste management and especially waste water management.
Waste water treatment aims at the concentration's reduction of BOD5 and includes different stages. In the beginning, the removal of the large size objects which are consisted in waste water, takes place (screening). The grease and the other floating substances are retained by an oil/grease separator. In cases where pH is higher than 8.5, HCl solution 30% is added automatically. Afterwards, waste water is pumped to a buffer tank, where pre-aeration occurs (nutrients H3PO4 and NH2CONH2). Biological treatment, that follows, takes place in two stages: aeration and sludge sedimentation. The treated effluent of the sedimentation tanks are led into a cylindrical tank, where the excess sludge is thickened. The rest of the sludge is circulated. Before dewatering the sludge, a conditioning is necessary. For this purpose a polyelectrolyte is dosed and mixed with the sludge. This acts as a flocculant. The sludge dewatering unit is a filter belt press. At the end the treated effluent is discharged.
The plant is designed for a flow of 3000 m3/d waste water and can reduce BOD5 from 2500-3000 mg/l to 250-300 mg/l. As far as the norm is 500 mg/l at the exit of the plant, BOD5 is decreased due to cost reduction. The plant belongs to the Technological Control Department.