As pulp and paper wastewaters are mostly deficient in nitrogen and phosphorus, historical practice has dictated that they cannot be effectively treated using microbiological processes without the addition of supplementary nutrients, such as urea and phosphoric acid. Supplementation is a difficult step to manage efficiently, requiring extensive post-treatment monitoring and some degree of overdosing to ensure sufficient nutrient availability under all conditions. As a result, treated wastewaters usually contain excess amounts of both nutrients, leading to potential impacts on the receiving waters such as eutrophication. N-ViroTech® is a highly effective alternative treatment technology which overcomes this nutrient deficiency/excess paradox. The process relies on communities of nitrogen-fixing bacteria, which are able to directly fix nitrogen from the atmosphere, thus satisfying their cellular nitrogen requirements. The process relies on manipulation of growth conditions within the biological system to maintain a nitrogen-fixing population whilst achieving target wastewater treatment performance. The technology has significant advantages over conventional activated sludge operation, including:
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Improved environmental performance. Nutrient loadings in the final treated effluent for selected nitrogen and phosphorus species (particularly ammonium and orthophosphate) may be reduced by over 90% compared to conventional systems;
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Elimination of nitrogen supplementation, and minimisation of phosphorus supplementation, thus achieving significant chemical savings and resulting in between 25% and 35% savings in operational costs for a typical system;
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Self-regulation of nutrient requirements, as the bacteria only use as much nitrogen as they require, allowing for substantially less operator intervention and monitoring.
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