Treatment of wastewater in milk collecting station
2006
Askinis, S.
The paper presents the test results of studies on the treatment of wastewater in experimental treatment facilities in a milk collecting station. The treatment process of wastewater was a follows: aeration-flocculation device -sedimentation pond - two-stage constructed wetlands. The laboratory investigations have shown that the primary treatment with quicklime (1 kg mE-3) reduces wastewater pollution by 54%, while the treatment with coagulant 'ZETAG 8660' (4 g mE-3) reduces it by even 68%. Such results were not obtained in the primary wastewater treatment stage under industrial conditions: biological oxygen demand (BOD5) in wastewater was reduced 27.2%, the amount of suspended sediment was reduced by 48.1%, the amounts of Ntotal and Ptotal decreased by 15.8% and 27% respectively. Such results much depended on the air temperature, inaccurate dosage of chemicals as well as on insufficient capacity of reaction and sedimentation reservoirs for 2.5 times higher amount of wastewater. However, despite such unfavourable conditions, this stage of treatment process was rather efficient: the pollution of wastewater with organic matter flowing into the stream did not exceed the maximum allowable rates. The average value according to BOD5 was 4 mg O2 lE-1, the highest BOD5 value was 9.6 mg O2 lE-1. From the environment protection point of view, it is particularly important that the removal of biogenic pollutants is quite sufficient in the wastewater treatment facilities. After the treatment process in wastewater treatment facilities, the amount of Ntotal decreased by 82.4% and the amount of Ptotal was reduced by even 97.3%.
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