Chemical and biological oxidation of sulphur compounds under anoxic conditions / Nurul Ayu Fatma Ramli

Microbial transformations of wastewater in sewer networks result in wastewater quality changes. These processes may occur in bulk water, biofilm and sewer sediment phases under aerobic, anoxic or anaerobic conditions. Anoxic conditions do not naturally occur in sewers but are caused by nitrate addition when managing odor and corrosion problems in sewer networks. The use of nitrate for the prevention of sulphide production is well documented. Batch test were designed and conducted to investigate the chemical and biochemical transformation rates of sulphur and nitrogen compounds under anoxic conditions in bulk water phase. The laboratory testing was conducted to establish the result. Throughout the experiment, the result for sulphur compounds in chemical transformation rate was found to be 0.00 mg SO4-S LAK , 0.01 mg SO3- S I/'h"1 and 0.03 mg S2O3-S l/h"1 while for nitrogen compounds it were found to be 0.01 mg NO3-N L'lKl and 0.00 mg NO2-N L h*1. The bio-chemical transformation rate for sulphur compounds are 0.38 mg SO4-S iA"1, 0.00 mg SO3-S L 'V and 0.67 mg S203-S iA"1. The value for nitrogen compounds are 1.62 mg NO3-N L^h"1 and 0.64 mg NO2-N L*!h . In sterilized wastewater the oxidation process is insignificant for chemical transformations. However, in active wastewater the oxidation process is significant for both chemical and biological transformations.