Biological Nutrient Removal

Biological Nutrient Removal   The Urban wastewater Treatment Directive has highlighted the need for the control of nutrients in sewage effluents discharging to sensitive areas. This control is required to reduce potential problems of eutrophication in fresh water lakes and rivers as well as coastal and estuarine areas. Within the Korea, TEI(TAEJIN ENGINEERING, INC)has the most sewage treatment works requiring nutrient removal and so we have taken action to investigate the implications of both Community policy and increased environmental awareness over the removal of nutrients from sewage works discharges.

In the past, Removal of Phosphates from Wastewater has been achieved by addition of chemicals, usually iron salts, to precipitate Phosphate. Chemical treatment increases sludge yield and leaves a residue of iron within the waste sludge. Biological nutrient removal does NOT increase sludge yield and provides a sludge RICH in nutrient which is ideal for application to agricultural land. Biological nutrient removal using the activated sludge process is an Environmentally Acceptable Method of Phosphate Removal. TEI is progressing research in this field here at the Inovation Centre and at a number of sites within the region.
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Biological phosphorus removal is achieved by a Modified Activated Sludge Process, incorporating Anaerobic and Aerobic zones. By the inclusion of an anoxic zone in the overall process, the Removal of Nitrogen can also be achieved. In the normal activated sludge process, phosphorus is used by the micro-organisms for growth , resulting in about 20% reduction in concentration. In the BNR process, the conditions are established for a particular group of anaerobic bacteria, Acinetobacter spp, to convert stored phosphorus into a form which can be assimilated in a subsequent aerobic stage of the process. In this way more than 90% removal of phosphorus can be achieved.
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The plant at the Inovation Centre treat sewage from a population of around 4,500 and it can be configured to operate in a number of ways in order to investigate the optimum design and operating parameters, such as:
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Overall control is by a programmable logic controller linked to a supervisory control system. An important part of the project is the demonstration of a compact modular design and its application to small scale biological nutrient removal plants
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