Farah Naemah Mohd Saad

Decolorization and mineralization of Amaranth dye using multiple zoned aerobic and anaerobic baffled constructed wetland

ABSTRACT The objective of this study is to determine the reduction efficiency of Chemical Oxygen Demand (COD) as well as the removal of color and Amaranth dye metabolites by the Aerobic–anaerobic Baffled Constructed Wetland Reactor (ABCW). The ABCW reactor was planted with common reed (Phragmite australis) where the hydraulic retention time (HRT) was set to 1 day and was fed with synthetic wastewater with the addition of Amaranth dye. Supplementary aeration was supplied in designated compartments of the ABCW reactor to control the aerobic and anaerobic zones. After Amaranth dye addition the COD reduction efficiency dropped from 98 to 91% while the color removal efficiency was 100%. Degradation of azo bond in Amaranth dye is shown by the UV–Vis spectrum analysis which demonstrates partial degradation of Amaranth dye metabolites. The performance of the baffled unit is due to the longer pathway as there is the up-flow and down-flow condition sequentially, thus allowing more contact of the wastewater with the rhizomes and micro-aerobic zones.

Performance of the hybrid growth sequencing batch reactor (HG-SBR) for biodegradation of phenol under various toxicity conditions

Hybrid growth microorganisms in sequencing batch reactors have proven effective for treating the toxic compound phenol, but the toxicity effect under different toxicity conditions has rarely been discussed. Therefore, the performance of the HG-SBR under toxic, acute and chronic organic loading can provide the overall operating conditions of the system. Toxic organic loading (TOL) was monitored during the first 7hr while introducing 50mg/L phenol to the system. The system was adversely affected with the sudden introduction of phenol to the virgin activated sludge, which caused a low degradation rate and high dissolved oxygen consumption during TOL. Acute organic loading (AOL) had significant effects at high phenol concentrations (600, 800 1000mg/L). The specific oxygen uptake rate (SOUR) gradually decreased to 4.9mg O2/(g MLVSS·hr) at 1000mg/L of phenol compared to 12.74mg O2/(g MLVSS·hr) for 200mg/L of phenol. The HG-SBR was further monitored during chronic organic loading (COL) over 67days. The effects of organic loading were more apparent at 800mg/L and 1000mg/L phenol concentrations, as the removal range was between 22%-30% and 18%-46% respectively, which indicated the severe effects of COL.

A Study on Hydrogen Sulphide as Potential Tracer in Landfill Gas Monitoring

Municipal solid waste (MSW) landfills are one of the major source of hydrogen sulphide (H2S) which is the offensive odours potentially creating annoyance in adjacent communities. This project focuses on H2S emission from landfills in Perlis, Malaysia. Landfill gas (LFG) samples were collected and analyzed accordance with NIOSH method 6013. The mean concentrations of H2S in Kuala Perlis Landfill and Padang Siding Landfill are 210.68 ppm and 242.85 ppm respectively. High concentrations of H2S may be a concern for employees working on the landfill site. These results indicate that workers should use proper personal protection at landfill when involved in excavation, landfill gas collection, and refuse compaction. The formation of H2S most likely to be contributed by the biological conversion of sulfate from gypsum-rich soils and landfill wastewater treatment sludges by sulfate-reducing bacteria (SRB) which can utilize dissolved sulfate as an electron acceptor. H2S is conveniently detected by hand held analyzer, such Jerome meter, landfill gas analyzer. In the organic range, in the ease of detection range in the dispersion rate within the landfill site, the monitored H2S gas form a very noticeable concentration with the travelling wind direction. It proved that the dispersion rate of H2S are suitable as tracer to detect route of travelling in a certain distance.