Sulphide formation in sewage pipes and influence of H2S to aerobic activated sludge microorganisms

The object of this work is to research the sulphide formation process in pressure pipesand how the sulphur rich wastewater influences treatment process in Kohtla-Jiirvewastewater treatment plant (WWTP),In this work the ISO 8192 standard test has been used to estimate the inhibition of oxygendemand of activated sludge microorganisms in different sulphide concentrations and pHvalues, Two wastewaters has been investigated - leachate from coke- and ash hills andwastewater from inflow ofKohtla-Jii.rve WWTP,The leachate from coke- and ash hills, rich of sulphates and sulphides, with high pHvalues from l O+ 12, did not cause significant inhibition of oxygen demand of activatedsludge microorganisms, After the leachate has been mixed with other sulphate andsulphide rich wastewaters with lower pH values, the mixed wastewater inhibits theoxygen demand of microorganisms in activated sludge process. One of the reasons is theincreased sulphide concentration but the essential factor is also decreasing of pH.