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Research suggests that a combination of phosphorus-laden sludge and dewatered anaerobically digested primary sludge offer agricultural sites a longer productive life than the primary sludge alone, and meet established heavy metal criteria. Data were obtained from studies conducted on landscape applications of sludges produced by Saskatchewan's Regina Wastewater Treatment Plant.

Enhanced biological phosphorus removal is a two-step process. The sequence of anaerobic environment followed by aerobic environment is essential for selection of biological phosphorus-removing culture. Anaerobically, phosphorus is released; subsequently, in the aerobic period, it is biologically removed. An effort has been made to study both phosphorus release and uptake at 25 [degrees] C and 10 [degrees] C in sequencing batch reactors using synthetic wastewater. In anaerobic phase the maximum phosphate released was 327% at 25 [degrees] C and 195% at 10 [degrees] C. Despite differences in temperature and initial concentration of released phosphorus, the effluent phosphate concentration was found to be the same at both temperatures.

Nitrate concentrations in surface water and especially in ground water have increased in Canada, the United States, Europe, and other areas of the world. This trend has raised concern because nitrates cause methemoglobinemia in infants. Several treatment processes including ion exchange, biological denitrification, chemical denitrification, reverse osmosis, electrodialysis, and catalytic denitrification can remove nitrates from water with varying degrees of efficiency, cost, and ease of operation. Available technical data, experience, and economics indicate that ion exchange and biological denitrification are more acceptable for nitrate removal than reverse osmosis. Ion exchange is more viable for ground water while biological denitrification is the preferred alternative for surface water. This paper reviews the developments in the field of nitrate removal processes.

Phosphorus is a key nutrient responsible for eutrophication. Conventional activated sludge process (ASP) removes approximately 30 to 40% phosphorus. Additional phosphorus removal has been achieved by incorporating an anaerobic stage before aerobic ASP. The application of technology, however, in cold-region countries is limited. Temperature is an important consideration in the design of any treatment process in cold regions. In this paper, the performance of biological phosphorus removal (BPR) systems at low temperatures has been reviewed. The mechanism of BPR has been considered to analyze the effect of reduced temperature. Chemical coprecipitation of phosphorus, and acetate and/or short chain fatty acid (SCFA) production may affect BPR efficiency. Both these aspects have been reviewed in systems other than BPR.

Byline: T. Mathialagan, T. Viraraghavan A review of published literature on the biosorption of chlorophenols using various biomasses is presented. Factors such as pH, time, temperature, ionic strength, type of biomass and type of chlorophenols influence the chlorophenol uptake by biomass. There is appreciable potential for biosorption of chlorophenols by most of the biomasses tested, although it is species dependent. The mechanisms of biosorption are generally speculated and understood only to a limited extent. More research and development of the various aspects of biosorption technology for removal of chlorophenols is recommended.