Abstract
Process removal nutrients, especially nitrogen – ammonia in municipal wastewater treatment is a challenger of design and operate wastewater treatment plant. Nowadays in Vietnam, technology SBR has been wide applied in biological wastewater treatment but the concentration of nitrogen – ammonia in treated water cannot achieve the discharge standard. For the purpose to reach the Vietnamese Standard A, the modification of SBR has been added the anoxic phase into operated cycle to create the denitrification’s environment and enhance performance of ammonia – nitrogen removal in municipal wastewater treatment at present and in the near future. The results of experiment shows that, the efficiency of N – NH4 removal in reactors sustainable in range 75 – 80% with the nitrogen loadings rate from 0.07 – 0.25 kg N – NH4/kg sludge/d. However, in 3 hours of anoxic phase, the value of specific denitrification rate is 0.10 – 0.15 kg N – NO3/kg sludge/d with the organic loadings rate in range 0.3 – 1.0 kg BOD/kg sludge/d and can reach the maximum is 0.2 kg N – NO3/kg sludge/d when the organic loadings rate increase to 2.0 kg BOD/kg sludge/d.
Highlights
Removing nutrients in wastewater treatment plants (WWTP), especially ammonia – nitrogen is a major challenge in the design of wastewater treatment systems because of their damaged on environment, public health, and economic concerns
In the biological wastewater treatment with activated sludge, denitrification occurs in anoxic environments, when the concentration of dissolved oxygen in range 0.2 – 2.0 mg/l and the Oxidation – Reduction Potential (ORP) from -200 to 200 mV in the reactor/tank
In the period of Ammonia loading rate 0.07 – 0.30 kg N – NH4/kg sludge/d, the efficiency removal of Classical reactor decreases from 70% to 50%, but the Modification one only decreases 10%
Summary
Removing nutrients in wastewater treatment plants (WWTP), especially ammonia – nitrogen is a major challenge in the design of wastewater treatment systems because of their damaged on environment, public health, and economic concerns. In the biological wastewater treatment with activated sludge, denitrification occurs in anoxic environments, when the concentration of dissolved oxygen in range 0.2 – 2.0 mg/l and the Oxidation – Reduction Potential (ORP) from -200 to 200 mV in the reactor/tank. Ludzack – Ettinger Process and Anoxic Step Feed, Source: Biological nutrient removal Operation in Wastewater treatment plants [1]. With the advantages about suitable for Vietnamese conditions such as easy control the treatment process in the wide range of pollutants, affected by tropical climate, or economic efficiency through reconstructed aerotank and saving electric – land using [5,6,7], more than 60% projects of urban WWTP in Vietnam with the capacity higher than 30,000 m3/d was SBR. The concentration of nutrients cannot achieve the discharge standard (Standard A of Vietnam) [8], because efficiency of nutrification and nutrient removal does not reach the design value [9]
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