Reported by Dr Megawati Omar, Research Management Institute, UiTM, Shah Alam
One of the ways water in drains can be smelly is due to the transformation of sulphur compounds. Anaerobic decomposition of wastewater in sewer systems that generate sulphur compounds have been identified as a major cause of problems of toxicity, foul odours and corrodibility. This happens due to the transformation of sulphur compounds in wastewater that forms hydrogen sulphide (H2S), which has caused serious problem in sewer systems.
Thus Saliha and her professor theorized and looked at how the microbial transformation in wastewater during transportation can improve the wastewater system. As basic kinetics of anoxic sulphide oxidation in sewer systems serves as an important tool to reduce the hydrogen sulphide problem in sewer systems (by the addition of nitrate) they discovered that odour from drains and corrosion of the sewer wall can be reduced. Secondly, as sulphide is reduced, the workers responsible for sewer systems will also be protected from its toxicity.
Their test was conducted on wastewater from a manhole near the in-sewer Processes Laboratory of the Faculty of Civil Engineering, of the Universiti Teknologi MARA, Shah Alamn campus. The wastewater was collected as a raw wastewater sample during the peak rate of the wastewater flow, that was between 8:30 am to 9:30 am. Making sure the anaerobic condition occurs naturally to assimilate the condition of experiment to that of in the sewer system, the collected bulk water samples were kept in an air tight container for 14 days before being tested in a batch test.
They found that the wastewater in sewer systems can oxidize sulphide biologically under anoxic conditions, thus they created a process to oxidize sulphide to sulphate in a single-step process. Also, nitrate was reduced to nitrogen gas through a two-step process. Hence, less odour was produced.
The result from this study can be used by local authorities to provide guidelines to enhance municipal wastewater treatments in sewer systems. On top of that, the results may be useful for wastewater engineering companies to upgrade the existing sewer systems to reduce odour, prevent corrosion problems and reduce health risk from hydrogen sulphide.
In the same vein, this study has also contributed in establishing basic kinetics and a pathway of sulphide oxidation under anoxic condition in bulk water phase. However, it is recommended that the transformation rate of sulphide in biofilm to establish full anoxic sulphur oxidation be investigated. Also it is suggested that studies be conducted on microrganisms activities at molecular level as this will enhance the understanding on microbial transformations of sulphur compounds.
Contact:
Suhaimi Abdul Talib
Faculty of Civil Engineering,
Universiti Teknologi MARA, Shah Alam,
MALAYSIA
Email: [email protected]
email: [email protected]
