Shahrom Md Zain

Contamination, bioaccumulation and toxic effects of perfluorinated chemicals (PFCs) in the water environment: a review paper

Perfluorinated compounds such as perfluorooctane sulfonate (PFOS) and perfluorooctane acid (PFOA) have been recognized as emerging environmental pollutants because of their ubiquitous occurrence in the environment, biota and humans. The paper focuses on the distribution, bioaccumulation and toxic effects of PFOS and PFOA in the water. From the available literature, tap and surface water samples in several countries were found to be contaminated with PFOS and PFOA. These compounds were detected globally in the tissues of fish, bird and marine mammals. Their concentrations from relatively more industrialized areas were greater than those from the less populated and remote locations. Blood samples of occupationally exposed people and the general population in various countries were found to contain PFOS and PFOA which suggested a possibility of atmospheric transport of these compounds. There is still a death of information about the environmental pathways of PFOS and PFOA. The presence of these compounds in the tap water, surface water and animal and human tissues indicates their global contamination and bioaccumulative phenomena in the ecosystems.

Biomethanation of kitchen waste and sewage sludge in anaerobic baffled reactor

Biomethanation is a promising method for transformation of organic fraction of municipal solid waste (OFMSW) to valuable energy. In addition, as OFMSW has considerable portion in any community generated solid waste, biomethanation reduces the total waste to be collected, transported and disposed to the landfill. In this study application of laboratory-scale anaerobic baffled reactor (ABR) for production of methane gas through co-digestion of kitchen waste and sewage sludge was investigated. Performance of four ABRs with identical volume of 75 l under hydraulic retention time (HRT) of 3 days and with kitchen waste and sewage sludge mixed at ratio of 100:0, 75:25, 50:50 and 25:75 was compared in terms of methane yield and microorganisms growth. Results indicate that, the ABR containing 75% kitchen waste and 25% sewage sludge had highest volumetric percentage of methane (>;80%). This amount was relatively reasonable for other samples except sample with 100 % kitchen waste (<; 20%). pH investigation shows sample containing 100% kitchen waste is slow compared to the others in term of higher-molecular-mass compounds breakdown as well as development of both acid formers and methane formers. This signifies that not only the suitable substrate but also proper development of different species of microorganisms is vital in any biomethanation system.

Production of renewable energy by transformation of kitchen waste to biogas, case study of Malaysia

Municipal Solid Waste (MSW) management has been highlighted by the Malaysian government as an important agenda in ensuring successful development of the country. Due to the fast growing urbanization and industrialization of the country, a tremendous increment of solid waste generation is an unavoidable occurrence. With increased levels of waste production, limited area for landfilling, and increased awareness of environmental impact, alternative methods for treatment of solid and agricultural wastes are being sought. Currently these wastes load to the dumping sites and release undesired methane into the atmosphere. A typical composition of MSW in Malaysia comprises as high as 70 to 80% of organic waste with high moisture content (80 to 85%), which is suitable for biological transformation to biogas. Therefore, in this study, application of an anaerobic digester for transformation of kitchen waste was investigated. The best organic loading rate (OLR) and slurry concentration for highest biogas production rate were examined. Results show COD reduction of 80, 97, 85, 80 and 70 % for OLR of 2, 4, 8, 15 and 20 kg/m3, respectively. The best biogas production rate (0.6 m3/kgVS) was achieved at slurry concentration of 40 g/L.

Effect of biological and coagulation pre-treatments to control organic and biofouling potential components of ultrafiltration membrane in the treatment of lake water

ABSTRACT Biological aerated filter (BAF), sand filtration (SF), alum and Moringa oleifera coagulation were investigated as a pre-treatment for reducing the organic and biofouling potential component of an ultrafiltration (UF) membrane in the treatment of lake water. The carbohydrate content was mainly responsible for reversible fouling of the UF membrane compared to protein or dissolved organic carbon (DOC) content. All pre-treatment could effectively reduce these contents and led to improve the UF filterability. Both BAF and SF markedly led to improvement in flux than coagulation processes, and alum gave greater flux than M. oleifera. This was attributed to the effective removal and/or breakdown of high molecular weight (MW) organics by biofilters. BAF led to greater improvement in flux than SF, due to greater breakdown of high MW organics, and this was also confirmed by the attenuated total reflection-Fourier transform infrared spectroscopy analysis. Coagulation processes were ineffective in removing biofouling potential components, whereas both biofilters were very effective as shown by the reduction of low MW organics, biodegradable dissolved organic carbon and assimilable organic carbon contents. This study demonstrated the potential of biological pre-treatments for reducing organic and biofouling potential component and thus improving flux for the UF of lake water treatment.