Sequencing Batch Reactor Process Research Articles

Effect of sequencing batch reactor (SBR)/granular activated carbon (GAC) bed and membrane hybrid system for simultaneous water reuse and membrane fouling mitigation

The objectives of this study are to assess the potential of an activated and granular sludge (AS and GS) sequencing batch reactor (SBR)/granular activated carbon (GAC) coupled with a membrane for achieving reclamation and reuse of real mixed wastewater and to evaluate the feasibility of the configured systems for achieving membrane fouling mitigation. A better performance of membrane filtration (MF) having lower membrane fouling was observed at both higher agitation velocity and lower permeate flux. Despite a twice shorter hydraulic retention time (HRT) than that of the AS-SBR/MF configured system, the performances of the GS-SBR/MF system without and with a GAC bed as a pretreatment for the MF process achieved higher efficiencies than those of the AS-SBR system for organics and nutrient removal and higher flux in the MF. The addition of a GAC filter after SBR processes was more effective in mitigating membrane fouling due to effective foulant removal. These results indicate that the GS-SBR as an alternative process for the AS-SBR or the addition of a GAC bed after the SBR process is needed to obtain the reusable water with good quality and to improve the fouling rate and filtration time of the MF process.

Integration of sequencing batch reactor and homo-catalytic advanced oxidation processes for the treatment of textile wastewater

It is unusual to observe completely treated textile wastewater in Ethiopia. It is impossible to get better quality of treated effluent with a single treatment stage. Therefore, in this study the removal of COD and color was carried out on a wastewater which was obtained from acrylic fiber processing textile industry using a single-stage Fenton oxidation, single-stage sequencing batch reactor (SBR) and also with the integration of SBR with Fenton oxidation. Optimum amount of process factors was used for both Fenton oxidation and SBR treatment stages. The combination of SBR and Fenton oxidation was revealed better removal efficiency than single SBR-stage treatment. The effluent obtained from SBR at steady-state conditions indicated a maximum COD and color removal of 74.1% and 64.6%, respectively. The effluent obtained from Fenton followed by SBR (Fenton + SBR) at steady-state conditions was indicated a maximum COD and color removal efficiency of 86.3% and 84%, respectively. The effluent obtained from SBR followed by Fenton (SBR + Fenton) for three Fenton oxidation experimental runs indicated a maximum COD and color removal of 80.2% and 73.6%, respectively. Among the three wastewater treatment schemes, chemical treatment before biological stage (Fenton + SBR) was the best treatment option and also showed better quality of effluent.

Treatment of High-Concentration Wastewater from an Oil and Gas Field via a Paired Sequencing Batch and Ceramic Membrane Reactor.

A sequencing batch reactor (SBR) and a ceramic membrane bioreactor (CMBR) were used in conjunction (SBR+CMBR) to treat high-concentration oil and gas field wastewater (HCOGW) from the China National Offshore Oil Corporation Zhanjiang Branch (Zhanjiang, Guangdong, China). The chemical oxygen demand (COD) and the oil concentrations in the wastewater were 20,000–76,000 and 600–2200 mg/L, respectively. After the SBR+CMBR process, the effluent COD and oil content values were less than 250 mg/L and 2 mg/L, respectively, which met the third level of the Integrated Wastewater Discharge Standards of China (GB8978-1996). Through microbiological analysis, it was found that the CMBR domesticated a previously unreported functional microorganism (JF922467.1) that successfully formed a new microbial ecosystem suitable for HCOGW treatment. In conjunction with the SBR process, the CMBR process effectively reduced pollutant concentrations in HCOGW. Moreover, economic analyses indicated that the total investment required to implement the proposed infrastructure would be approximately 671,776.61 USD, and the per-unit water treatment cost would be 1.04 USD/m3.

Suitability of SBR for Wastewater Treatment and Reuse: Pilot-Scale Reactor Operated in Different Anoxic Conditions.

The present study investigates the performance of a pilot-scale Sequencing Batch Reactor (SBR) process for the treatment of wastewater quality parameters, including turbidity, total suspended solids (TSS), total solids (TS), nitrogen (ammonia (NH3–N), nitrite (NO2−), and nitrate (NO3−), phosphate (PO43−), the chemical oxygen demand (COD), and the 5-day biological oxygen demand (BOD5), from municipal wastewater. Two scenarios, namely, pre-anoxic denitrification and post-anoxic denitrification, were investigated to examine the performance of a pilot-scale SBR on the wastewater quality parameters, particularly the nitrogen removal. The correlation statistic was applied to explain the effects of operational parameters on the performance of the SBR system. The results revealed that the post-anoxic denitrification scenario was more efficient for higher qualify effluent than the first scenario. The effluent concentrations of the targeted wastewater quality parameters obtained for the proposed SBR system were below those of the local standards, while its performance was better than that of the North Sewage Treatment Plant, Dharan, Eastern province, Kingdom of Saudi Arabia (KSA), in terms of the BOD5, COD, TN, and PO43- treatment efficiencies. These results indicated the suitability of SBR technology for wastewater treatment in remote areas in the KSA, with a high potential of reusability for sustainable wastewater management.

Distribution and Removal of Pharmaceuticals in Liquid and Solid Phases in the Unit Processes of Sewage Treatment Plants.

In this study, we analyzed 27 pharmaceuticals in liquid and solid phase samples collected from the unit processes of four different sewage treatment plants (STPs) to evaluate their distribution and behavior of the pharmaceuticals. The examination of the relative distributions of various categories of pharmaceuticals in the influent showed that non-steroidal anti-inflammatory drugs (NSAIDs) were the most dominant. While the relative distribution of antibiotics in the influent was not high (i.e., 3%–5%), it increased to 14%–30% in the effluent. In the four STPs, the mass load of the target pharmaceuticals was reduced by 88%–95% mainly in the biological treatment process, whereas the ratio of pharmaceuticals in waste sludge to those in the influent (w/w) was only 2%. In all the STPs, the removal efficiencies for the stimulant caffeine, NSAIDs (acetaminophen, naproxen, and acetylsalicylic acid), and the antibiotic cefradine were high; they were removed mainly by biological processes. Certain compounds, such as the NSAID ketoprofen, contrast agent iopromide, lipid regulator gemfibrozil, and antibiotic sulfamethoxazole, showed varying removal efficiencies depending on the contribution of biodegradation and sludge sorption. In addition, a quantitative meta-analysis was performed to compare the pharmaceutical removal efficiencies of the biological treatment processes in the four STPs, which were a membrane bioreactor (MBR) process, sequencing batch reactor (SBR) process, anaerobic–anoxic–oxic (A2O) process, and moving-bed biofilm reactor (MBBR) process. Among the biological processes, the removal efficiency was in the order of MBR > SBR > A2O > MBBR. Among the tertiary treatment processes investigated, powdered activated carbon showed the highest removal efficiency of 18%–63% for gemfibrozil, ibuprofen, ketoprofen, atenolol, cimetidine, and trimethoprim.

Feasibility of Biological Elimination of COD, Ammonia-Nitrogen and Total Nitrogen from HTS Molecular Sieves Wastewater Using SBR Processes

The wastewater from hollow titanium silicate (HTS) zeolite consists essentially of high concentrations of COD and salt, and low ammonia-nitrogen concentrations (or high, sometimes). These chemical pollutants are produced in very large quantities during oil refining and are very difficult to manage on site. In addition, they can be very harmful to the environment when released without any treatment. The aim of this study is to evaluate, on the one hand, the feasibility of removing the COD from HTS wastewater using a sequencing batch reactor (SBR) and, on the other hand, to test the combined effect of nitrification and denitrification under different conditions of treatment on the elimination of Total Nitrogen (TN) from HTS wastewater containing a high concentration of ammonia-nitrogen. SBR intermittent domestication tests of sludge have been successfully carried out with wastewater from a municipal treatment plant with a COD removal rate of 87%. Subsequently, HTS wastewater containing high concentrations of COD was treated by this SBR system. After three months of operation, the efficiency of COD elimination fluctuated between 47% and 67%. Therefore this result could serve as a precursor to a possible second COD bioprocessing. The results obtained during nitrification of the same HTS molecular sieves wastewater with low C/N ratio gave, under an operating temperature below 10°C (winter conditions), less than 16% of total nitrogen (TN) removal. When the temperature was increased to 40°C, the TN removal efficiency remained worse. These observations make it possible to affirm that the change in temperature solely had no effect on oxidation of TN. Thereafter, two SBR devices were used for the denitrification process: one containing HTS wastewater, activated sludge and glucose as carbon source, and the other only HTS wastewater and activated sludge. In both cases, the elimination of TN still low even with an increase in the amount of glucose. These situations show that the TN removal was not only depended on type of carbon source. Based on the results of nitrification and denitrification tests, it may turn out that the activated sludge microorganisms’ activities were affected by the HTS molecular sieves wastewater high concentration as well as the salinity (about 3%) of this kind of wastewater.

Efikasnost pogona za galvansko tretiranje otpadnih voda "Frad" Aleksinac

The technological process of Galvano-chemical protection, according to qualitatively-quantitative characteristics, represents one of the most complex contaminants in wastewater. A large number of contaminants (metal ions, cyanides, acids, bases, grease and oils, organic solvents, surfactants, phosphates, etc.), found in galvanic wastewater are treated through conventional methods (chemical oxidation and reduction, neutralization, sedimentation, coagulation and flocculation). The reason why galvanic wastewater treatment systems in the Republic of Serbia are conventional is of economic nature. The present study has been undertaken to evaluate the performance of Sewage Treatment Plant located at Aleksinac, Company of "Frad" district which is based on Sequential Batch Reactor process. Performance of this plant is an essential parameter to be monitored as the treated effluent is discharged into the Moravica River. The Performance Evaluation will also help for the better understanding of design and operating difficulties (aeration, blowers, etc.) in Sewage Treatment Plant. Research goal: The efficiency of sewage treatment plants can be illustrated by a study on the evaluation of pollutant levels of the influent and the effluent at the treatment plant of sewage treatment plants discharging into the environment.

Effluent Treatment Technologies And Cost Research

The Common Effluent Treatment Plants (CETP) minimizes the pollution from industrial effluents. This plant monitors the reduction of physical and biochemical parameters such as total suspended solids (TSS), biological oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), heavy metals etc. The Sequential Batch Reactor (SBR), a variation of the ASP, combines all the treatment steps and processes into a single basin. An improved SBR process is Attached Growth Batch Reactor (AGBR) technology that provisions for microbial growth on the settled media/bed to treat the industrial wastewater using enzymes. This technology, when used to treat polluted river water, achieved about 90% of reduction of wastewater parameters. Hence the same is envisioned for the treatment of industrial effluent. In all the above methods the sludge settlement occurs. It contains biodegradable carbon content which could be used as feed for Biogas Digesters to produce Methane. The present study aims at examining the benefits of combining AGBR and Biogas Digester to implement the 3Rs (Reduce, Recycle, Reuse) [1].

In-situ sludge settleability improvement and carbon reuse in SBR process coupled with hydrocyclone

The settleability performance of activated sludge (AS) is a very important indicator in the biological treatment of wastewater. In this paper, we investigated the influence of hydrocyclone treatment on sludge settleability and explored the influence mechanism by sorting the excess sludge (ES) with a hydrocyclone. A lateral-line test of the treatment process of the campus wastewater treatment plant (WWTP) at East China University of Science and Technology (ECUST) was carried out by using a sequencing batch reactor (SBR) AS process equipped with a hydrocyclone. The results showed that the sludge flocs rotate and revolve in the hydrocyclone; the resulting shear and centrifugal stress cause the flocs to crack into smaller pieces and can break the extracellular polymeric substances (EPS) on the floc surface, thus changing the floc structure and density. After density sorting by the hydrocyclone, the particle size of the sludge floc returned to the bioreactor decreased, the compactness increased, the settleability performance improved, the sludge volume index (SVI) decreased by 6.1%, and the effluent suspended solid (SS) concentration decreased by 6.1%. Meanwhile, the broken EPS caused organic carbon sources, such as polysaccharides and proteins, in the floc channels to be released into the water phase, supplementing the carbon source for denitrification and improving the effluent water quality: the removal rates of soluble chemical oxygen demand (SCOD), total nitrogen (TN), and NH4-N increased by 6.9%, 8.9%, and 8.4%, respectively.

Performance evaluation of a hybrid sequencing batch reactor under saline and hyper saline conditions

Significant rise in concentration of saline wastewater entering the treatment plants has been resulting in many problems in the biological treatment processes. On the other hand, the specific conditions of physicochemical treatment methods for saline and hyper saline wastewater have limited their application on a large-scale. Over the past few decades, Sequencing Batch Reactor (SBR) process has been widely used as an efficient, well-designed and practical approach for treatment of domestic and industrial wastewater due to its cost-effectiveness and simplicity. SBR Performance can enhance by providing simultaneous suspended and attached growth of microorganisms which act as a hybrid growth. In this study, a lab-scale Hybrid Sequencing Batch Reactor (HSBR) with 6.4 l working volume was used to examine the effect of salinity (NaCl), increased from 0 to 6.7% (g NaCl/ L wastewater), on the biological treatment. Therefore, COD, MLSS, MLVSS and SVI parameters have been measured over a period of 7 months of operation. The operational parameters namely pH, dissolved oxygen (DO) and temperature were 7.5–8.5, 1.5–6.8 mg /L and 20–25 °C respectively during whole experiment. Influent COD of synthetic wastewater was maintained at 650 ± 25 mg/L. The HSBR Cycle time including, influent feeding, React, Settling and effluent discharge were 1/20/1/1 h respectively. Results indicated that by increasing salt concentration from 0 to 67.7 g NaCl/L, the COD removal efficiency reduced from 94.22 to 53.69%. Moreover, as the NaCl concentration increased, MLSS rose up to 69%, while MLVSS almost stayed constant and SVI dropped by 83%. The results indicated that the simultaneous use of suspended and attached growth of microorganisms and gradual increasing of salt content of wastewater could lead to greater biomass concentration and ultimately improvement in the degradation of organic matter. Besides, settling performance and its velocity were noticeably improved by increasing salinity.

Improving Wastewater Nitrogen Removal and Reducing Effluent NOx - -N by an Oxygen-Limited Process Consisting of a Sequencing Batch Reactor and a Sequencing Batch Biofilm Reactor

Abstract A series of reactors including a sequencing batch reactor (SBR) and a sequencing batch biofilm reactor (SBBR) were used for nitrogen removal. The aim of this study was simultaneous removal of NH4+-N and NOx–-N from synthetic wastewater. In the novel proposed method, the effluent from SBR was sequentially introduced into SBBR, which contained 0.030 m3 biofilm carriers, so the system operated under a paired sequence of aerobic-anoxic conditions. The effects of different carbon sources and aeration conditions were investigated. A low dissolved oxygen (DO) level in the biofilm depth of the fixed-bed process (SBBR) simulated the anoxic phase conditions. Accordingly, a portion of NH4+-N that was not converted to NO3–-N by the SBR process was converted to NO3–-N in the outer layer of the biofilm in the SBBR process. Further, simultaneous nitrification and denitrification (SND) was achieved in the SBBR where NO2–-N was converted to N2 directly, before NO3–-N conversion (partial nitrification). The level of mixed liquid suspended solids (MLSS) was 2740 mg/l at the start of the experiments. The required carbon source (C: N ratio of 4) was provided by adding an internal carbon source (through step feeding) or ethanol. Firstly, as part of the system (SBR and SBBR), SBR operated at a DO level of 1 mg/l while SBBR operated at a DO concentration of 0.3 mg/l during Run-1. During Run-2, the system operated at the low DO concentration of 0.3 mg/l. When the source of carbon was ethanol, the nitrogen removal rate (RN) was higher than the operation with an internal carbon source. When the reactors were operated at the same DO concentration of 0.3 mg/l, 99.1 % of the ammonium was removed. The NO3–-N produced during the aerobic SBR operation of the novel method was removed in SBBR reactor by 8.3 %. The concentrations of NO3--N and NO2–-N in the SBBR effluent were reduced to 2.5 and 5.5 mg/l, respectively. Also, the total nitrogen (TN) removal efficiency was 97.5 % by adding ethanol at the DO level of 0.3 mg/l. When C:N adjustment was carried out SND efficiency at C:N ratio of 6.5 reached to 99 %. The increasing nitrogen loading rate (NLR) to 0.554 kg N/m3 d decreased SND efficiency to 80.7 %.

Achieving deep-level nutrient removal via combined denitrifying phosphorus removal and simultaneous partial nitrification-endogenous denitrification process in a single-sludge sequencing batch reactor

The feasibility of coupling denitrifying phosphorus removal (DPR) with simultaneous partial nitrification-endogenous denitrification (SPNED) was investigated in a single-sludge sequencing batch reactor for deep-level nutrient removal from municipal and nitrate wastewaters. After 160-day operation, the DPR process simultaneously reduced most PO43−-P and NO3−-N anoxically, and the SPNED process achieved further total nitrogen (TN) removal at low dissolved oxygen condition with TN removal efficiency of 90.8%. The effluent NH4+-N, PO43−-P and TN concentrations were 1.0, 0.1 and 7.2 mg/L, respectively. Microbial analysis revealed that Dechloromonas (6.7%) dominated DPR process, whereas the gradually enriched Nitrosomonas (4.5%) and Candidatus Competibacter (6.8%) conducted SPNED process accompanied with sharply eliminated Nitrospirae (1.4%). Based on these findings, a novel strategy was proposed to achieve further nutrient removal in conventional treatment through integrating the DPR-SPNED process. As a result, ∼100% of extra carbon and ∼10% of oxygen consumptions would be reduced with satisfactory effluent quality.

Optimization of nitrogen removal performance in a single-stage SBR based on partial nitritation and ANAMMOX

A partial nitritation (PN)/anaerobic ammonium oxidation (ANAMMOX) process in sequencing batch reactor (SBR) was successfully developed to treat high-strength ammonium wastewater. The feed distribution in the SBR cycle and sub-cycles was considered as the main operating strategy, and was optimized using a response surface methodology (RSM)-based optimization technique. In the SBR cycle, the maximum nitrogen removal rate (NRR) of 0.79 ± 0.01 kg m−3 d−1 was achieved by applying a feed distribution strategy that considered the kinetic characteristics of ANAMMOX and ammonia oxidizing bacteria (AOB). However, this strategy negatively affected the nitrogen removal efficiency (NRE) due to alkalinity loss. Therefore, the feed distribution in the SBR sub-cycles with respect to the NRE and the NRR was further studied. The nitrogen removal performance was optimized in the optimum region and an NRE of 88% and an NRR of 0.84 kg m−3 d−1 were achieved. The optimized model was verified in confirmation test. The RSM-based optimization results provide insights into the feed distribution strategy for achieving single-stage PN/ANAMMOX SBR operation.

Evaluation of COD and turbidity removal from woodchips wastewater using biologically sequenced batch reactor

The wood industry consumes a lot of water. Due to the reduction of water resources in the world, the treatment of this contaminated water is very essential. In this study, the removal efficiencies of the chemical oxygen demand (COD) and turbidity from woodchips wastewater with the use of a sequencing batch reactor (SBR) were studied at a bench scale. Woodchips wastewater samples were collected with a COD of 1300 mg L−1 and a turbidity of 93 NTU. The optimization of the SBR process was investigated by response surface methodology (RSM) based on a central composite design (CCD). A quadratic polynomial model was fit to the data with R2 of 0.9919 for COD reduction, R2 of 0.9910 for turbidity removal, and R2 of 0.9945 for sludge volume Index (SVI), respectively. The effect of three parameters, including initial COD, mixed liquor suspended solids (MLSS), and Hydraulic retention time (HRT) on the COD reduction and turbidity removal were evaluated. The initial COD (A), MLSS (B), cycle time (C), AB, AC, BC, A2, B2, and C2 were considered as the affective parameters in the COD reduction. Initial COD (A), MLSS (B), A2, B2, C2, AC, and BC were observed as the remarkable model terms on the turbidity removal. Also, initial COD (A), MLSS (B), cycle time (C), B2, C2, and BC were the significant model factors in SVI index. At optimal conditions, involving an initial COD of 1000 mg L−1, an organic loading rate (OLR) of 0.450 kg COD/m3d, MLSS of 3000 mg L−1, and cycle time of 24 h, we observed 94.6% of COD reduction, 98.5% turbidity removal, and 79 mL g−1 SVI. The results also showed that the kinetic of COD reduction and turbidity removal could be represented by the pseudo-second-order model.

Design of Domestic Sewage Treatment System Based on Programmable Logic Controller

This paper focuses on the design of software and hardware for the purification and recycling of domestic sewage discharged from a residential area. According to the characteristics of domestic sewage, the process used in this paper is determined to be Sequencing Batch Reactor (SBR) process and the allocation of system input/output (I/O) port. According to the determination of the process flow to select appropriate instruments, sensors and other equipment, using Programmable Logic Controller (PLC) to design the system in manual mode and automatic mode of the program respectively, to achieve the function of sewage treatment.

Evaluation of predominant factor for shortcut biological nitrogen removal in sequencing batch reactor at ambient temperature.

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 NH4+, since the system has to maintain a high free ammonia (FA, NH3) 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.

Design of Sewage Treatment Plants for High-Density Urban Reclamation Land

The success of any coastal reclamation project depends strongly on a sound planning and design practices. Due to the land use limitations, sewage treatment plant (STP) of the reclamation land should be fully studied to save land and reduce its adverse effects on the environment. This research focuses on the selection of biological treatment process for a novel STP, as various pollutants of the sewage can be effectively removed via the biological process. The paper presents a design of the STP implemented in Johor as an example, to achieve the goal of ‘zero discharge’ in the reclaimed wetland. The domestic sewage is treated, recycled and reused in the artificial wetland as an ecological green water to achieve Class IIB standard (effluent quality). The novel STP design comprised of the Immobilized Aerobic Biofilm (BioAX) and Mass Bio System (MBS) was compared against the conventional Sequencing Batch Reactor (SBR) process. Combination BioAX + MBS process is advantageous due to significantly less land needed, lower power consumption and lower sludge generation. The system was demonstrated as a viable process to treat the sewage wastewater in the reclamation land to meet Class IIB discharge at a lower environmental footprint, saving up to 50 % of the area.

Effects of biomass pyrolysis derived wood vinegar on microbial activity and communities of activated sludge

The effects of wood vinegar (WVG) on microbial activity and communities of activated sludge were investigated in a sequencing batch reactor (SBR) process. Results showed that the optimal WVG concentration was 4 μL/L when the pollutants removal efficiency and microbial activity were promoted by a WVG dilution factor of 1000. WVG could reduce the increase in microbial species richness, which led to a more notable variety of microbial species diversity. The enhanced microbial activity and communities were addressed to the promotion of 7 main classes of microbes in Proteobacteria, Bacteroidetes, Acidobacteria, and Nitrospirae phyla. The growth of ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), and main genera of denitrifying bacteria (DNB), phosphorus-accumulating organisms (PAOs), and glycogen-accumulating organisms (GAOs) could be promoted by WVG, which improved the sewage treatment effectiveness in a SBR.

An Evaluation of the Water Quality Characteristics of Shipboard Sewage Disposal and Usability Based on Water Quality Enhancement

International Maritime Organization recognizes vessel-induced pollution as a global issue. The designation of the Baltic Sea as the special uncontaminated area was the beginning of the regulations for preventing marine pollution. In this regard, a process is needed which meets the provisions of MEPC. 227(64) for the specificity and constrained conditions of vessels, removes both nitrogen and phosphorus, requires convenient operation and low construction cost and is little affected by the load variation of inflow. This study used an SBR(sequencing batch reactor) and MBR(membrane bioreactor) combined process to iterate the stirring and aeration process and maintained the ratio of raw wastewater parameters (C:N:P) to be 10:3:1 in order to assess the quality and future availability of ultimate outflow in each time period of the stirring and aeration process. The removal efficiencies of COD and T-N exceeded 90% and 93% respectively. However, a detailed mechanism will be identified by a further study on nitrogen removal issues like DO aeration condition, stirring duration, ORP and NO3. As the removal efficiency of T-P exceeded 95%, the SBR and MBR process formed anaerobic and aerobic conditions without a separate coagulation process for removing phosphorus, thereby enabling easy phosphorus release and uptake. The optimal stirring and aeration condition seems to be 70–50 min. A further study will be efficiently conducted by focusing on the water quality criteria of the Maritime Environment Protect Committee. 227 (64) for E. coli and chlorine and a detailed mechanism.

Full-Scale Processing by Anaerobic Baffle Reactor, Sequencing Batch Reactor, and Sand Filter for Treating High-Salinity Wastewater from Offshore Oil Rigs

High-salinity wastewater discharged from offshore oil rigs (WORS) is harmful to marine environments. Therefore, WORS should be properly treated before discharge. In this study, a full-scale anaerobic baffle reactor (ABR) + sequencing batch reactor (SBR) + sand filter (SF) process was used for the first time to treat WORS at an inshore treatment terminal. After seeding with residual sludge from a municipal wastewater treatment facility, the start-up of the ABR and SBR was accomplished in one month. During a steady running period, the ABR + SBR process showed stable performance in treating WORS. The results of microbial diversity indicated that Rhizobiales, Thermotogales, and Actinomycetales were the most abundant genera in the ABR sample, while Acidobacteria DRC31, Lactobacillales, and Bacillales prevailed in the SBR sample. The results showed that ABR + SBR is a reliable process for WORS treatment, with the treated WORS meeting the National Sewage Comprehensive Emission Standards (GB8978-1996).