Wastewater Treatment and Reuse Technologies

This edited volume is a collection of 12 publications from esteemed research groups around the globe. The articles belong to the following broad categories: biological treatment process parameters, sludge management and disinfection, removal of trace organic contaminants, removal of heavy metals, and synthesis and fouling control of membranes for wastewater treatment

Simultaneous nitrification/denitrification and trace organic contaminant (TrOC) removal by an anoxic-aerobic membrane bioreactor (MBR)

Simultaneous nitrification/denitrification and trace organic contaminant (TrOC) removal during wastewater treatment by an integrated anoxic-aerobic MBR was examined. A set of 30 compounds was selected to represent TrOCs that occur ubiquitously in domestic wastewater. The system achieved over 95% total organic carbon (TOC) and over 80% total nitrogen (TN) removal. In addition, 21 of the 30 TrOCs investigated here were removed by over 90%. Low oxidation reduction potential (i.e., anoxic/anaerobic) regimes were conducive to moderate to high (50% to 90%) removal of nine TrOCs. These included four pharmaceuticals and personal care products (primidone, metronidazole, triclosan, and amitriptyline), one steroid hormone (17β-estradiol-17-acetate), one industrial chemical (4-tert-octylphenol) and all three selected UV filters (benzophenone, oxybenzone, and octocrylene). Internal recirculation between the anoxic and aerobic bioreactors was essential for anoxic removal of remaining TrOCs. A major role of the aerobic MBR for TOC, TN, and TrOC removal was observed

Enhancement of trace organic contaminant degradation by crude enzyme extract from Trametes versicolor culture: Effect of mediator type and concentration

The performance of two redox mediating compounds, namely 1-hydroxybenzotriazole (HBT) and syringaldehyde (SA), was compared in terms of enhancement of enzymatic degradation of a diverse set of 14 phenolic and 16 non-phenolic trace organic contaminants (TrOCs) and the toxicity of the treated media. Extracellular enzyme extract (predominantly containing laccase) from Trametes versicolor culture achieved efficient degradation (70-95%) of nine phenolic and one non-phenolic TrOCs. Mediator dosing extended the spectrum of efficiently degraded TrOCs to 13 phenolic and three non-phenolic compounds, with moderate improvements in removal of a few other non-phenolic compounds. TrOC removal efficiency improved significantly as the HBT dose was increased from 0.1 to 0.5 mM, while SA achieved similar removal over dosage range of 0.1-1 mM. A particular concern was the toxicity of the treated media (1200-2200 times that of the control) for all SA dosages applied. Overall, HBT at a concentration of 0.5 mM achieved the best removal without raising concern regarding toxicity of the treated media. The results are discussed in the light of the redox potential of the enzyme-mediator cocktail, the balance between the stability and reactivity of the radicals generated and their cytotoxic effects

A Study on Solid Waste Management System of Dhaka City Corporation: Effect of Composting and Landfill Location

This study has analyzed the generation and characteristics of solid waste in Dhaka city, along with the associated environmental impacts and existing solid waste management practices. Special focus was given on the effect of composting on final disposal of solid waste and effect of landfill site location on transportation cost. An estimate of the future generation rate indicates that the present generation rate of 3500 tons/day may exceed 30 thousand tons/day by the year 2020.The mixed waste dumped at dumping sites is characterized with high organic content and high moisture content (about 80% and 50-70% by weight, respectively). According to required landfilling areas, projected assuming 50% collection efficiency, on the year 2020, land requirements with composting of 40-80% of the organic wastes range from 167.11 acres/yr. to 96.97 acres/yr., while that without any composting stands at 206.31 acres/yr. With composting, the peak rate of greenhouse gas methane generation would be as low as half of that for without any composting. Results from this study shows that the imminent selection of dumping sites away from the city center due to unavailability of land and/or higher land price will induce three times as high daily waste transportation cost as compared to that at present

Application of membrane technology for the development of sustainable biotechnology processes

The scope of application of membranes in biotechnology has widened significantly in the recent years. Although many of the membrane options are yet to achieve wide industrial applications, they show tremendous potential for the transformation and synthesis of value-added products, energy production, therapeutic applications and environmental remediation. This chapter provides an overview of membrane applications in selected established and emerging biotechnology processes. Approaches to overcoming the technology bottlenecks that impede the scale-up of such systems have been discussed in this chapter