Simultaneous removal of nitrogen, phosphorus and COD in an integrated OCO reactor

Abstract

An integrated OCO reactor with two side-ditch separators based on the anaerobic/anoxic/oxic (A2/O) process was developed for municipal wastewater treatment in this study. The effects of dissolved oxygen (DO) concentration, hydraulic retention time (HRT) and the ratio of chemical oxygen demand (COD) to total nitrogen (C/N) in the influent were investigated for optimization, in order to achieve the removal of total nitrogen (TN), total phosphorus (TP) and COD in the reactor simultaneously. When the DO concentration of 2.0 mg/L in the aerobic zone, HRT of 12 h and C/N ratio of 8:1 were applied in the reactor, the superior removal efficiencies of COD, TN and TP reached 96%, 81% and 92%, respectively. The modification in integrated OCO system was characterized by the mixing of the liquid refluxed from anoxic and aerobic zones with the influent in the anaerobic zone. And the risk of activated sludge bulking was decreased successfully by enhancing phosphorus removal without any chemical auxiliary methods. Quite precise prediction results with the correlation coefficients (R) of 0.9584-0.9948 were forecasted by the back-propagation neural network model. All the results indicated that the integrated OCO process is able to remove TN, TP and COD in a reactor simultaneously.

Evaluation of performance and microbial community successional patterns in an integrated OCO reactor under ZnO nanoparticle stress

“…The integrated OCO reactor with an effective volume of 240 L has been operating for more than one year, and the reactor has been described previously. 12 The synthetic wastewater consisted of glucose, sucrose, soluble starch, NH 4 HCO 3 , KH 2 PO 4 , and a trace element solution (including MgCl 2 , CaCl 2 , MnSO 4 , CoCl 2 , CuSO 4 , FeSO 4 and H 3 BO 3 ) as previously reported. 13 The parameters COD, TN and TP of the synthetic wastewater were adjusted to about 300 mg L −1 , 37 mg L −1 and 5 mg L −1 , respectively.…”

“…In the present study, activated sludge systems in an integrated OCO reactor (an anaerobic/anoxic/oxic (A 2 /O) process with a shape similar to the letters of the alphabet “OCO”) 12 were treated with various concentrations of ZnO NPs (0.25 mg L −1 , 0.8 mg L −1 , 1.5 mg L −1 and 4 mg L −1 ) for a performance period of 80 days, and the shifts in the microbial communities were revealed using Illumina Miseq pyrosequencing of the 16S rRNA gene. The objectives of this study were as follows: (1) to evaluate the ecotoxicity of ZnO NPs on wastewater treatment systems, and (2) to illustrate the responses of microbial communities to the long-term exposure of relatively lower concentrations of ZnO NPs.…”

Modeling the kinetics and cost performance index of high rate up‐flow anaerobic, anoxic, oxic bioreactor for meat wastewater treatment

“…This result was previously reported for simultaneous removal of COD and nutrient (Li et al . ). However, the COD/TN ratio is the rate‐limiting factor in biological nitrogen removal and the high values cause high growth rate of heterotrophs than autotrophic nitrifiers (Bayo et al .…”

“…The adverse effect of HRT on TN removal rate in the same condition was observed in all experimental runs. The removal efficiency of TN was increased while the HRT was changed from 7.5 to 12.5 h. In fact, the low HRT resulted in high F/M ratio and short time for nitrifiers and denitrifiers to utilize substrate (Li et al 2014). The total nitrogen removal rate was enhanced to 0.78 g/l.d, while the HRT dropped to 5 h. In addition, the high nitrogen loading rate in low HRT resulted in an increase of the removal rate from 0.13 to 0.58 g/l.d.…”