Monitoring and control of biological nutrient removal in a Sequencing Batch Reactor (original) (raw)
Related papers
Sequencing Batch Reactor System for Nutrient Removal: ORP and pH Profiles
Journal of Chemical Technology & Biotechnology, 1996
The sequencing batch reactor (SBR) process is known for its flexibility to meet a wide range of treatment needs, including nutrient removal. However, information related to the operational stability of SBR nutrient removal systems and control parameters to adjust the cyclic duration is sparse. Consequently, this study was undertaken to identify process parameters (pH and oxidation reduction potential) that could be useful for monitoring and real-time control purposes. In general, the system achieved removal efficiencies of 91, 98 and 98%, respectively, for Chemical Oxygen Demand, total nitrogen and phosphate at the solids retention time of 10 days, with a cyclic duration of 6 h. Shock loadings of nitrogen (20 mg dm-3 of NHa-N, four cycles) exhibited little impact on effluent quality, except for a higher nitrate content. Activated sludge settled well throughout the entire study period. Several significant points associated with different reactions within SBR cycle, e.g. end of nitrification, end of phosphate release and completion of phosphate uptake, were identified in pH profiles. Slope changes in pH profiles (dpH/dt, or d2pH/dt2) were found to better represent the corresponding biological reactions. The application of these significant points in pH profiles as real time control parameters appears promising.
Water Environment Research, 2008
Two biological nutrient removal modes, consisting of anaerobic, anoxic, and oxic sequences, were tested in a full-scale sequencing batch reactor. The modes, identified as BNR-S1 and BNR-S2, had average total nitrogen removals of 84 and 89%, respectively, for the months of August to October. Over the same period, total phosphorus removals for BNR-S1 and BNR-S2 were 88 and 87%, respectively. In contrast, total nitrogen and total phosphorus removals for the regular aerobic mode were 54.7 and 44.7%, respectively. When the wastewater temperature changed from approximately 20 to 158C in the winter months, total nitrogen and total phosphorus removals for BNR-S2 were reduced to 81 and 70%, respectively. Total nitrogen effluent concentrations were between 2.5 and 4 mg-N/L (at approximately 208C), while the effluent total phosphorus concentrations were between 1 and 2 mg/L. The BNR-S2 mode was found to require less energy per kilogram of soluble chemical oxygen demand removed than the regular and BNR-S1 modes. Water Environ. Res., 80, 257 (2008).
Biochemical Engineering Journal, 2006
In this study, an anaerobic/aerobic/anoxic process (referred to as an AOA process) using a sequencing batch reactor (SBR) was proposed for simultaneous phosphorus and nitrogen removal from wastewater. The AOA process was stably operated over more than one year when a certain amount of carbon substrate (40 mg-C/L in a reactor) was supplemented to inhibit aerobic phosphate uptake. The average nitrogen and phosphorus removal efficiencies were 83% and 92%, respectively. It was demonstrated that phosphate-accumulating organisms (PAOs) capable of utilizing nitrite as an electron acceptor, the so-called denitrifying phosphate-accumulating organisms (DNPAOs), could exist in the AOA process. Moreover, the ratio of anoxic phosphate uptake rate (PUR) to aerobic PUR (anoxic/aerobic PUR ratio), which indicates the fraction of DNPAOs in total PAOs, was experimentally evaluated. The results indicate that the AOA process has a much larger anoxic/aerobic PUR ratio than the conventional A 2 O (anaerobic/anoxic/aerobic) and AO (anaerobic/aerobic) processes. In conclusion, the AOA process allows DNPAOs to take an active part in simultaneous nitrogen and phosphorus removal in an SBR when a suitable amount of carbon substrate is supplied at the start of aerobic conditions.
The effect of an anoxic zone on biological phosphorus removal by a sequential batch reactor
Bioresource Technology, 2004
Nitrate can affect phosphate release and lead to reduced efficiency of biological phosphorus removal process. The inhibition effect of remaining nitrate at the anaerobic/anoxic phases was investigated in a lab scale sequencing batch reactor. In this study the influence of denitrification process on reactor performance and phosphorus removal was examined. The experiments were carried out through simultaneous filling and decanting, mixing, mixing-aeration and settling modes. Glucose and acetate were used as carbon sources. The proposed treatment system was capable of removing approximately 80% of the influent PO4-P, 98% NH4-N and 97% COD at a SRT of 25 days. In the fill/decant phase, anoxic and anaerobic conditions prevailed and a large quantity of nitrate was removed in this stage. In the anoxic phase the remaining nitrate concentration was quickly reduced and a considerable amount of phosphate was released. This was attributed to the availability of acetate in this stage. For effective nitrogen and phosphate removal, a short anoxic phase was beneficial before an aerobic phase.
Role of nitrate in biological phosphorus removal in a sequencing batch reactor
World Journal of Microbiology and Biotechnology, 2006
The effects of nitrate on phosphorus release and uptake in a sequencing batch reactor for biological phosphorus removal was investigated. The addition of nitrate decreased phosphorus release in the anaerobic stage. The synthesis of poly(hydroxyalkanoates) was decreased with the presence of nitrate, possibly due to the competitive utilization of the carbon source by PHA synthesis and denitrification of nitrate. Instead of oxygen, nitrate could be used as an electron acceptor for phosphorus removal. However, the simultaneous addition of nitrate and acetate greatly reduced the phosphorus removal rate. Phosphate and nitrate could be removed simultaneously with nitrate as the electron acceptor, and the continuous and steady feeding of nitrate was beneficial to phosphate removal.
Resources, Conservation and Recycling, 1994
The Sequencing Batch Reactor (SBR) system employing activated sludge process is an alternative wastewater treatment technology. A cycle of the conventional SBR system generally consists of five periods, with complete aeration during the React period to oxidize the organic matter and nitrify the ammonium-nitrogen of wastewater. Laboratory-scale reactors were used to evaluate the feasibility of incorporating alternative aerobic-anoxic-aerobic stages within the React period for simultaneous removal of organic matter, N and P. Two cycles of SBR process per day were maintained. Under the operation strategy of 0.75-h FILL, 8-h REACT (with continuous aeration), 3.25-h SETTLE, DRAW and IDLE periods, the treatment performance became consistent after running the system for two to four cycles (1-2 days). The percentages of both BOD5 and COD removal were around 94% from Cycle 2 onwards, the BOD5 content dropped from initial 251 mg L-1 to less than 14 mg L-1 in the final effluent. A steady nitrification (about 97%) was obtained from Cycle 4 onwards, with l mg NH+-N L-J and 25 mg NO~-N L-t present in the final effluent. This suggested that the time required for SBR system to acclimate and reach an equilibrium state was relatively short when compared with the time needed for continuous flow activated sludge system. The findings also show that 4-h aeration during the REACT period was long enough to achieve more than 90% nitrification. With the incorporation of a 3-h anoxic stage after the initial 4-h aeration of the REACT period, a satisfactory denitrification process was observed, with nitrate level dropped from 27 to around 8 mg L-~ within 3 h. The second aeration stage did not cause significant change in wastewater nitrogen content. The wastewater phosphate content declined rapidly during the initial 4-h aeration and P-release was not observed during the anoxic stage. A slight reduction of P was found in the second aeration stage suggesting that more P-uptake occurred in this stage. A 12-h cyclic SBR system with the incorporation of 4-h aerobic, 3-h anoxic and final 1-h aerobic stages into the 8-h REACT period was demonstrated to be able to remove C, N and P simultaneously.
Sustainability
Enhanced biological phosphorus removal (EBPR) is an obscure but economical and helpful technology for removing phosphorus biologically from wastewater. A 3-MLD capacity pre-anoxic selector-attached sequencing batch reactor (SBR) treated municipal wastewater from the residents of IIT Roorkee. The treatment in the plant satisfied the effluent discharge standards in all respects except phosphorus, observed during an intensive two-year study. An elaborated 80-day study was performed to enhance and improve the plant’s performance in terms of phosphorus removal specifically, with run 1: solid retention times (SRT) reduced from 56 to 20 days (t = 35 d), run 2: lowering the diffuser’s running time from 15 min to 10 min in anoxic cum anaerobic selector chambers (dissolved oxygen (DO) concentration reduced to <0.15 mg/L) along with reducing SRT to 15 days (t = 25 d), and run 3:intensive reduction in SRT to ≤10 days (t = 20 d). During run 3, the increment in the enhanced biological phosphor...
Biological phosphate removal from wastewater with oxygen or nitrate in sequencing batch reactors
Environmental Technology Letters, 1988
To obtain kinetic and stoichiometric information on the biological excess phosphorus removal phenomenon, two enhanced cultures of polyP organisms (mainly Acinetobacter spp.), one in a three-stage Bardenpho system at 20 days sludge age, the other in a UCT system at 10 days sludge age, were developed by continuously feeding a pure acetate substrate as influent. Further information was obtained from four types of batch tests undertaken on sludge samples abstracted from the enhanced culture systems; (i) aerobic digestion, (ii) acetate addition under anaerobic conditions, followed by (iii) aerobic conditions and (iv) acetate addition under aerobic conditions. A kinetic model for biological excess phosphorus removal was set up with the information collected. The predicted behaviour of this first modelling attempt compares favourably with observed behaviour in the batch test types (i) to (iii) but further research is required to resolve some of the problems highlighted by the model.
THE STUDY OF NUTRIENT BALANCE IN SEQUENCING BATCH REACTOR WASTEWATER TREATMENT
The Sequencing Batch Reactor (SBR) is very suitable system for combined wastewater treatment of organic compounds and nutrient removal. Reactor can work at different conditions such as anaerobic, anoxic or aerobic. The objective of our research work was to study the influence of phosphorus concentration on N removal in a SBR wastewater treatment at various COD:N:P ratios. The results showed that the removal of N was not dependent on initial P concentration, but P removal was related to P concentration in the original wastewater. All experiments were carried out with synthetic wastewater to which different amounts of P were added. The optimal COD:N:P ratio was 100:11:2 and the BOD5:N:P ratio was 100:15:2.6.
Bioprocess and Biosystems Engineering, 2019
The shortcut biological nitrogen removal (SBNR) process requires less aeration and external carbon due to the oxidization of ammonia into nitrite and its direct denitrification to nitrogen gas during the biological nitrogen removal process. However, this process produces a poor effluent containing NH 4 + , since the system has to maintain a high free ammonia (FA, NH 3) concentration. To overcome this drawback, in this study, the solid retention time (SRT) and the dissolved oxygen (DO) concentration were controlled to achieve both a high ammonia removal rate and nitrite accumulation in the sequencing batch reactor (SBR) process, which can remove nitrogen from wastewater to the desired concentration and provide high free ammonia inhibition and continuous shock loading. When sufficient DO was supplied, nitrite did not accumulate with a 20-day SRT, but the wash-out of nitrite oxidizers in a shorter SRT resulted in a high nitrite accumulation. When DO acted as a limitation, nitrite accumulated at all SRTs. This indicates that nitrite accumulation is more highly influenced by SRT and DO concentration than by FA inhibition. Also, as nitrite accumulated over a 10-day SRT regardless of DO concentration, the accumulation was more highly influenced by SRT than by DO concentration.