Abstract
A single-stage anaerobic ammonium oxidation (ANAMMOX) process with an integrated biofilm–activated sludge system was carried out in a laboratory-scale flow-through reactor (volume = 57.6 L) to treat pharmaceutical wastewater containing chlortetracycline. Partial nitrification was successfully achieved after 48 days of treatment with a nitrite accumulation of 70%. The activity of ammonia oxidizing bacteria (AOB) decreased when the chemical oxygen demand (COD) concentration of the influent was 3000 mg/L. When switching to the single-stage ANAMMOX operation, (T = 32–34 °C, DO = 0.4–0.8 mg/L, pH = 8.0–8.5), the total nitrogen (TN) removal loading rate and efficiency were 1.0 kg/m3/d and 75.2%, respectively, when the ammonium concentration of the influent was 287 ± 146 mg/L for 73 days. The findings of this study imply that single-stage ANAMMOX can achieve high nitrogen removal rates and effectively treat pharmaceutical wastewater with high concentrations of COD (1000 mg/L) and ammonium.
Highlights
Pharmaceutical wastewater is rich in organic pollutants, ammonia (NH3 ), and multiple inhibitory materials that can adversely impact the performance of wastewater treatment
It is necessary to combine anaerobic ammonium oxidation (ANAMMOX) with partial nitrification in a single reactor, which is known as the single-stage ANAMMOX process [5,6]
The findings for the partial nitrification system investigated in the present study suggests that high NH3 removal rates can be achieved when the chemical oxygen demand (COD) concentration, NH4 + –N
Summary
Pharmaceutical wastewater is rich in organic pollutants, ammonia (NH3 ), and multiple inhibitory materials that can adversely impact the performance of wastewater treatment. The ammonium (NH4 + ) concentration of most pharmaceutical wastewater effluent does not meet the Chinese discharge standard due to the high NH4 + concentration of influent and the limited removal efficiency of current treatment processes, including nitrification–denitrification. In the single-stage ANAMMOX process, NH4 + is partially oxidized to NO2 − by ammonia oxidizing bacteria (AOB), after which, NO2 − and residual NH4 + are converted to N gas by anaerobic ammonium-oxidizing bacteria [7]. This process has many advantages, such as no need for external carbon, low excess sludge production and a high treatment efficiency in treating industrial wastewater with high ammonium [8]
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