Traditional approach for nutrient approval
One of the most significant changes in global discharge requirements is the shift to nutrient removal (nitrogen and phosphorus) to avoid eutrophication. A typical nutrient removal strategy would require twice the current energy utilised to treat wastewater and a reduction in the potential gas production from biological sludge digestion.
Anammox, a "new" bacteria found around two decades ago, is capable of transferring nitrogen from ammonia and nitrite to free nitrogen via an entirely different mechanism. When compared to nitrification- de nitrification, the following advantages can be acquired by following this path:
a. A reduction of 63% in oxygen demand (electrical power) and nearly 100 percent in carbon demand
b. Sludge generation is reduced by 80%.
What is Biological Nutrient Removal?
BNR (Biological Nutrient Removal) is a process for eliminating nitrogen and phosphorus from wastewater before it is discharged into surface or ground water.
Cultural eutrophication (nutrient enrichment owing to human activities) in surface waterways is caused by rising concentrations of hazardous nutrient compounds, particularly nitrogen and phosphorus, in municipal wastewater treatment plant effluent. Summer algal blooms are a common example of eutrophication, and they can cause issues for ecosystems and humans alike, including low dissolved oxygen, fish kills, murky water, and the extinction of desirable flora and fauna.
Even though traditional biological processes customized to fulfil secondary treatment effluent standards frequently refuse to remove total nitrogen (TN) and total phosphorus (TP) to the extent required to protect receiving waters, wastewater treatment facilities are increasingly being required to implement processes that decrease effluent nutrient concentrations to safe levels. This can be difficult for wastewater treatment plants as it usually requires significant process changes, like rendering a partof the aeration basin anaerobic and/or anoxic, which decreases aerobic volume and restricts nitrification capability.
The process of BNR
To reduce eutrophication in receiving water bodies, biological nutrient removal (BNR) of nitrogen and phosphorus has been widely used in wastewater treatment practise, both for the upgrade of existing wastewater treatment facilities and the construction of new facilities. However, the technical difficulty of balancing influent chemical oxygen demand (COD) for both biological phosphorus (P) and nitrogen (N) elimination offers obstacles in the application of BNR activated sludge AS systems.
Key parameters for process optimization includes sludge age and aerated/unaerated bulk fractions. Considerations about process sustainability and carbon footprint minimization are posing new obstacles, since influent COD, N, and P are increasingly being recognised as resources that should be reclaimed rather than merely eliminated. Energy recovery from influent wastewater via sludge digestion is one method, but it poses a unique problem for BNR: the creation of side streams with high nutrient and low COD loads.
Finally, under some conditions, relatively large quantities of nitrous oxide emissions, a potent greenhouse gas, have been seen in the BNR process, particularly in the presence of high nitrite concentrations. The benefits of employing process modelling tools are explored in the context of optimising BNR operations to meet effluent regulations as well as sustainability and carbon footprint reduction targets.
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Netsol can help maintain groundwater and surface water safe and clean by providing biological nutrient removal technology.