Combining Oily Wastewater with Domestic Wastewater for further Treatment by Biofiltration Method

Issues concerning stormwater runoff quality and it impact on the ecosystem of the
receiving water bodies have lead towards stormwater best management practice. One of
the stormwater management practices is the use of biofiltration systems that allow
variety of pollutants removal mechanisms. There are three main mechanisms of
pollutants removal involved within the system which are physical, chemical and
biological processes. Current application of the biofiltration focuses mainly on treating
ordinary stormwater runoff but not for oily stormwater runoff. This study examines the
potential application of biofiltration system in treating oily wastewater with addition of
domestic wastewater. Laboratory scale biofiltration columns consisting of sand for
bottom layer, activated carbon for middle layer and planting media for the top layer
were used in this study. Four columns were constructed and the combined wastewater
was left in the system for a period of 2 days, 4 days, 7 days and 10 days for each
columns. The parameters for influent and effluent wastewater in term of chemical
oxygen demand (COD), total organic carbon (TOC), total suspended solid (TSS),
turbidity, nutrients content (ammonia-nitrogen, nitrate-nitrogen and total phosphorus),
and zinc were analyzed. The hydraulic conductivity of the filter media was 0.0177
mm/sec and the pH of the soil was 7.61. The results indicate reduction of all the
pollutants after treatment. The biofiltration system able to remove up to 90% of COD,
35% of TOC, 88% of TSS, 70% of turbidity, 77% of ammonia-nitrogen, 86% of nitratenitrogen,
and 86% of phosphorus after 10 days of retention time. According to
Environmental Quality (Sewage Industrial Effluent Regulations, 1979), the effluents
quality meets the standard A limit