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Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Ambiente e Água is the property of Revista Ambiente e Agua and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Water pollution is one of the serious environmental problems threatening the sustainable development of human civilization. Many phenolic compounds are hazardous, toxic, endocrine disrupting, mutagenic, teratogenic, and/or carcinogenic. They also cause severe damages to marine ecosystem. Accordingly, their removal from polluted wastewaters prior to its discharge to the environment is a mandatory task. This work reports the biodegradation of phenol with enhanced efficiency in a sequencing batch reactor (SBR) after an acclimatization procedure with mixed culture activated sludge. The effects of temperature, initial phenol concentration, pH and time on phenol biodegradation were investigated. The system also showed high degree of stability and resistance to a load shock by increasing the initial concentration of phenol from 500 to 1000 mg/L. [ABSTRACT FROM AUTHOR]

The performance of traditional and magnetized activated sludge treatment systems was compared in a sequencing batch reactor. Four influencing factors, namely, magnetic powder dosage, temperature, aeration time, and magnetic field size, which affected the efficiency of sludge treatment were investigated with the evolution of the principal sewage indexes: chemical oxygen demand, ammonia nitrogen, total nitrogen, and total phosphorus. Results revealed that the efficiency of sewage treatment with magnetized activated sludge was better than that of traditional activated sludge. Its elimination rates of COD, ammonia nitrogen, TN, and TP were approximately 96.4%, 98.9%, 86.4%, and 94.2%, respectively, compared with the activated sludge that was not exposed to a magnetic field (90.7%, 78.4%, 53.5%, and 87%, respectively). The magnetic powder dosage of 0.5 g/L was optimal for pollutant removal. The temperature of 25 °C-30 °C, aeration time of 4 h, and applied magnetic field of 200 Gs achieved the best effect in the comprehensive consideration of economic aspects and processing indicators. [ABSTRACT FROM AUTHOR]

• P. putida F1 strain could be functionally encapsulated in PVA/alginate beads. • PVA/alginate immobilized P. putida F1 strain could be used in an aerobic SBR for cometabolic TCE removal. • Effects of fill time, toluene and TCE concentrations, and metals on cometabolic TCE removal in the aerobic SBR were discussed. • A mathematic model was developed to describe the behavior of cometabolic TCE removal in the aerobic SBR. Toluene and Trichloroethylene (TCE) are two of the most common organic contaminates at hazardous sites and contaminated water. In this study, a sequencing batch reactor (SBR) inoculated with PVA/alginate-immobilized Pseudomonas putida F1 was used for biological treatment of toluene and TCE contaminated wastewater. Moreover, a mathematical model was developed to simulate the dynamic behavior of a SBR treating competitive contaminates. Results showed high removal efficiencies of both toluene and TCE in the effluents. For the duration of filling time, an instantaneous fill was the optimum for moderate amount of toluene and TCE. Toluene concentration affected TCE degradation. The lower the toluene presence, the higher the removal efficiency of both toluene and TCE. Interestingly, the presence of 20 mg/L iron, or 1 mg/L nickel stimulated the degradation rates of both toluene and TCE. However, the degradation rate was reduced when both 20 mg/L iron and 1 mg/L nickel were presented simultaneously. The model developed in this research was able to simulate the kinetic behaviors of toluene and TCE removal in the SBR successfully. [ABSTRACT FROM AUTHOR]

The aim of this research was to improve the removal of organic matter and nutrients from wastewater from pig farms in a combined batch reactor performed as anaerobic-aerobic sequential. For this purpose, it was suggested to include recirculation cycles of wastewater in a sequentially pulsed manner in the anaerobic treatment followed by intermittent aeration in the aerobic-anoxic treatment. This novelty implemented in both sequential reactors was studied under pilot scale conditions. The process of pulsed intermittent recirculation allowed better contact between the microorganisms and organic matter, and intermittent aeration improved the removal of nutrients, primarily nitrogen (nitrification and denitrification), total phosphorous and organic matter. The best configuration tested for the combined system was the one consisting of pulsed intermittent recirculation with 1 hour of recirculation and 3 hours rest in the anaerobic step and 2 hours of aeration and 1 hour without aeration cycle in the aerobic step. The removals achieved were 98 ± 1% of total organic matter, 86 ± 5% of soluble organic matter, 96 ± 1% of total phosphorus and 55 ± 18% of total nitrogen. Hence, it was demonstrated that a combined system with pulsed intermittent recirculation in the anaerobic stage and intermittent aeration in the aerobic stage could enhance the overall treatment of swine wastewater. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Beijing Institute of Technology is the property of Beijing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The performance and microbial community of an anoxic-aerobic sequencing batch reactor (SBR) treating saline wastewater were investigated at different influent COD/N ratios. The average COD removal efficiencies at steady states were 87.46%, 73.75%, 64.87% and 88.34% at the COD/N ratios of 20, 10, 6 and 30, respectively. The average NH4+-N removal efficiencies were 79.74%, 74.34%, 64.55% and 89.29% at the COD/N ratios of 20, 10, 6 and 30, respectively. No obvious accumulation of NO2--N and NO3--N in the effluent was found during the whole operational period. The specific ammonium oxidation rate (SAOR), specific nitrite oxidation rate (SNOR) and specific oxygen uptake rate (SOUR) increased with the decrease of COD/N ratio from 20 to 6, whereas the specific nitrate reduction rate (SNRR) decreased. The diversity indices of microbial community in the SBR were 2.19, 2.10, 2.17 and 2.07 at the COD/N ratio of 20, 10, 6 and 30, respectively. Some bacteria were present at all the COD/N ratios, such as Nitrosomonas sp., Ohtaekwangia kribbensis and Propionicimonas paludicola, suggesting these bacteria could adapt to the shock of influent COD/N ratio. [ABSTRACT FROM AUTHOR]

This study explores economic and environmental impacts of a community-scale potable water recycling facility (WRF) by developing an optimal capacity and dispatch model, formulated as a mixed-integer linear program (MILP) that minimizes utility service costs, operating costs, and annualized capital costs where water recycling is augmented by service from central utilities. Model constraints govern operations of a sequencing batch reactor, reverse osmosis unit, and equalization equipment by enforcing flow balances. A solution method is also presented for a special case where water demand is constant, allowing WRF configurations to be screened for feasibility with minimal computational requirements. The generalized model is parameterized for a new residential community in Austin, TX to explore sensitivity to key parameters. Case study results indicate the WRF increases annualized costs by 15% relative to a business-as-usual (BAU) scenario without water recycling. Utility service demands for water (−50%) and sewer (−74%) decrease in the case study, accompanied by significant increases to electricity consumption (+167%) and indirect carbon emissions (+163%). Parameter exploration identifies regions where the WRF could be cost-effective based on utility rates, water demand, and capital costs. In systems facing supply constraints, the WRF modeled herein is a feasible alternative for incrementally expanding water supplies. [ABSTRACT FROM AUTHOR]

This study investigated the anaerobic digestion of Ulva biomass as an approach to diversifying energy sources and managing seaweed waste in a cost-effective manner. Ulva species are often identified as the main culprit of serious macroalgal blooms around the world, and their sulfur-rich nature causes difficulties in handling the biomass. Two reactors in continuous (Rc) and sequencing batch (Rs) modes were operated with decreasing hydraulic retention time in a stepwise manner from 20 to 6 days. Rs allowed significantly higher methane productivity (0.19–0.22 L/g chemical oxygen demand [COD] fed) and biomass retention capacity than Rc (0–0.16 L/g COD fed) throughout the experiment. Interestingly, sulfide production was also higher in Rs than in Rc. These findings, together with microbial quantification results, suggested that Rs operation enhanced biomass retention and the activity of both methanogens and sulfate-reducing bacteria. The Rc microbial community was less diverse and more variable than the Rs community. Accordingly, the performance of Rc was more significantly affected by changes in hydraulic and thus organic loads. Aceticlastic Methanosaetaceae dominated the methanogen community in both reactors, with the abundance of methanogens being significantly higher in Rs than in Rc. This may explain the more efficient and stable methane production despite the greater sulfidogenic activity in Rs, particularly at high hydraulic loads. Together, the results suggest that sequencing batch operation is advantageous over conventional continuous flow operation for the biomethanation of Ulva biomass and potentially other sulfur-rich feedstocks. [ABSTRACT FROM AUTHOR]

Wastewater treatment using sequencing batch reactor (SBR) has certain advantages over conventional activated sludge system. The performance of sequencing batch reactor in treating high C/N ratio was investigated with suspended polyurethane and polystyrene attached growth biomass configuration. A sequence of 4 hr HRT, 0.3 month SRT and 1kg COD/m3 was employed to study treatment efficacy. Treatment performance was assessed by means of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal. Operational parameters were pH, dissolve oxygen (DO), suspended solids (SS), volatile solids (VS), Sludge volume index (SVI), sludge density index (SDI) and these parameters were monitored throughout the operational period. COD removal in suspended growth biofilm bioreactor (SGSBBR) was 96.6±1.5 and in attached growth biofilm bioreactor (AGSBBR PU) 97.1±1.2; (AGSBBR PS) was 96.7±0.96. COD removal efficiency of both systems was almost equal however TN and TP removal of AGSBBR was 6-7% higher than SGSBBR. Ratio of mixed liquor suspended and volatile growth of biomass ranges from 1-3. Adsorption of naphthalene was also observed in batch experiments on biomass at variable pH. Acidic pH provide reducing medium in solution and enhanced adsorption. Enhanced performance of AGSBBR with addition of media provides attachment surface and enhances mineral removal efficiency. [ABSTRACT FROM AUTHOR]

Residential complexes discharge huge quantities of wastewater, which has a negative impact on nearby water bodies. Moreover, the treatment of this type of wastewater requires a large area, which could be a challenge as construction sites are normally limited in size. Different technologies have been used for the treatment of residential complexes’ wastewater (RCWW). Compared to the conventional wastewater treatments methods, sequencing batch reactors (SBRs) are lower cost and have smaller area requirements and sludge bulking rarely occurs. A considerable number of researchers have been optimising SBR operating conditions to gain a better removal efficiency of undesired wastewater pollutants. However, many researchers have reported bad, slow or incomplete particle settling. This study examines the impact of organic loading rate (OLR) on the effluent quality and sludge settling performance in a sequencing batch reactor. Four SBR reactors were used in this study; the working volume of each one is 5l. The reactors were operated under different glucose concentrations (750, 1000, 1250 and 1500 mg/l), constant aeration, 1.0 l/min, ±20 C° temperature and 6 h cycle time. Each cycle of the SBR operation included Fill (30 minutes), React (240 minutes), Settle (30 minutes), Draw (30 minutes) and Idle (30 minutes). Influent and effluent samples were analysed for COD, NH3-N, NO3-N and NO2-N. In addition, the sludge volume index (SVI) and a morphological study were used to study the sludge characteristics. The SVI and morphological study results showed a direct relationship between the glucose concentration and sludge settling behaviour. The results obtained from this study, which operated for 120 days, showed that the sequencing batch reactor could biodegrade up to 93.2%, 95.2%, 94.9% and 96.5% for COD, NH3-N, NO3-N and NO2-N respectively with glucose concentration between 750 and 1250 mg/l, and a steady sludge settling performance occurred during that range. [ABSTRACT FROM AUTHOR]

Domestic wastewater consists of considerable concentrations of pollutants that can boost water eutrophication if not treated before final discharge, which could damage the ecosystem and negatively affect human health. Sequencing batch reactor (SBR) technology is considered a promising biological wastewater treatment technology to address these issues. In recent years, SBR selection has increased as an effective technology for the treatment of domestic and industrial wastewaters due to its setup simplicity and ease of operation. However, many researchers have reported differences in cycle time. The importance and originality of this study is that it explores the parameters of pH, temperature, oxidation-reduction potential (ORP) and dissolved oxygen (DO) throughout the SBR cycle to predict the end of the treatment cycle. A laboratory-scale SBR was used in this study with a five-litre working volume. It was equipped with four electronic sensors (probes) to monitor the pH, ORP, temperature and DO. The SBR was operated under constant aeration, 1.0 l/min, ±12 C° temperature and 6 h cycle time. Each cycle of the SBR operation included Fill (30 minutes), React (240 minutes), Settle (30 minutes), Draw (30 minutes) and Idle (30 minutes). Influent and effluent samples were analysed for COD, ammonia-N and nitrate-N. The pH, ORP and DO values at the end of the 6 h HRT treatment cycle were between 6.6-7.9, 147-169 mV and 4.6-6.6 mg/l respectively. The results show complete degradation of COD and nitrogen compounds was seen when the DO profile increased due to bacterial respiration. The results prove that online monitoring of SBR operating parameters could significantly predict the end of the treatment cycle, and the pH, DO and ORP profiles could be used as onsite process control parameters. [ABSTRACT FROM AUTHOR]

An industrial wastewater treatment plant (WWTP) in Australia has long suffered from bulking problems associated with the proliferation of Thiothrix spp. The WWTP consists of a covered anaerobic lagoon (CAL) followed by a sequencing batch reactor (SBR). The CAL functions as both an anaerobic digester and surge lagoon for the irregular flow of wastewater generated from the production of seasonal products. Chemical analysis of the raw influent showed it was composed of a mixture of organic acids, phenols and alcohols. The CAL effluent was characterised by high acetic acid and phenolic concentrations. An attempt was made to manipulate the SBR microbial community to improve settling by direct feeding small volumes of raw influent into the SBR. After raw feeding, the plant ceased bulking as the settled sludge volume reduced from 930 to 200 mL L −1 . 16S rRNA gene profiling and biovolumes of SBR samples revealed major changes in the microbial community. The Thiothrix spp. population decreased from 36.8% to 0.2%, and Zoogloea spp. dominated all samples after raw feeding. Therefore, direct feeding is proposed as a control method for industrial plants with surge/anaerobic lagoons in order to manage the bulking problems caused by Thiothrix spp. in downstream SBRs. [ABSTRACT FROM AUTHOR]

Due to the high cost of bioplastic production, sesame wastewater, generated from the sesame seed hulling process, was investigated to be used as inexpensive and renewable carbon source for the production of biodegradable polyhydroxyalkanoate (PHA) by extreme Haloferax mediterranei. The sesame wastewater (SWW) was hydrolyzed using different concentrations of hydrochloric acid (0.4. 1.00 and 2.00 M) at different period of times (15, 60 and 90 min). The concentration of salt (NaCl) and nitrogen source (NH 4 Cl and yeast) required for H. mediterranei cells growth and the accumulation of PHA biopolymer was optimized. A maximum 0.53 g/L concentration of PHA was achieved when the SWW extract media was supplemented with 100 g/L NaCl and 6.0 g/L yeast extract. The cultivation was scaled-up using sequencing batch reactor (SBR) fermentation under non-sterile conditions. The SBR results showed that SWW needs an auxiliary carbon source to obtain high PHA production. Consequently, the system fed with SWW and glucose produced higher PHA (20.9 g/L) than the system fed with SWW. [ABSTRACT FROM AUTHOR]

The presence of antibiotics in water and wastewater is a serious environmental concern of emerging interest globally. Their effective removal with a single treatment process is, however, challenging because of their widely varying characteristics, and requires innovative integration of treatment processes. In this study, sonophotocatalytic oxidation process was integrated with an aerobic sequencing batch reactor (SBR) for the comprehensive removal of a mixture of antibiotics. Initially, a Central Composite Design using Response Surface Methodology was used to optimise the operational parameters, viz. ultrasound (US) frequency, pH, and catalyst dosage, for the removal of Ciprofloxacin (CPX), Amoxicillin (AMX), and Tetracycline (TTC) in simulated wastewater. An optimised condition of 20 kHz US frequency, 6.59 initial pH, and 0.94 g L−1 catalyst dosage was observed for the maximum pollutant removal. These experimental conditions were subsequently used for combined sonophotocatalysis-aerobic SBR treatment. Three SBR systems representing a control system, pre-treated system, and untreated system, were used for the study. All three systems were able to achieve an average COD and NH 4 +-N removal of 85 % and 98 %, respectively. Results from the biological systems concluded that an enhanced CPX and TTC removal was observed in the pre-treated system, whereas maximum AMX removal was observed in the untreated SBR system. The metagenomic analysis confirmed the significant difference of microbial species with the addition of pretreated and untreated wastewater into the biological reactor, and pretreated system having higher number of species and greater biodiversity in comparison to untreated system. • Sonophotocatalysis and aerobic SBR treatment for pharmaceutical removal. • Better removal of ciprofloxacin and tetracycline by sonophotocatalytic pretreatment. • Better removal of amoxicillin in direct SBR system. • Pretreatment helped better sludge properties in SBR system. • Pretreatment helped in sustaining microbial richness and diversity in SBR. [ABSTRACT FROM AUTHOR]

The study focuses on evaluation of occurrence of four priority phthalates in sewage and their removal in sequencing batch reactor (SBR), activated sludge process (ASP) and up flow anaerobic sludge blanket (UASB) reactor based full scale sewage treatment plants (STPs). Mean concentration of total four phthalates in raw sewage and secondary sludge was in the range of 35.5–46.1 μg/L and 26.1–71.8 mg/kg respectively. The concentration of phthalates in anaerobic sludge was more (71.8 mg/kg) than aerobic sludge from SBR (26.1 mg/kg) and ASP (48.4 mg/kg). Overall removal of phthalates by biodegradation and adsorption was >75% in all STPs. However, biodegradation was the main removal process. A significant portion of incoming phthalates (18–31%) was removed in primary settling tanks as well. Phthalate removal and conventional performance of STPs showed positive correlation with value of spearman correlation coefficient in the range of 0.443–0.583. The study may act as a contribution to the understanding which is required to improve the removal of phthalates or similar organic micropollutants in wastewater treatment. [ABSTRACT FROM AUTHOR]

There has been a rapid increase of fish industries across the world in recent years. The conditions in the fish industries are often nasty with the continual generation of liquid wastes. Sequencing batch reactor (SBR) is a widely used activated sludge modification, working on the basis of filling, reacting, decanting, and settling occurred within the same reactor. In this study, fish processing wastewater was treated in a 5 liter cylindrical SBR. The effects of different sludge retention times (SRT) on the removal efficiencies on chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were examined. The SBR was fed with an organic loading rate of 0.5 mg COD/mg Mixed Liquor Volatile Suspended Solids (MLVSS) at 10, 15 and 20 days of SRT. Daily two cycles consisting of fill, anaerobic/anoxic/aerobic, settle and decant steps were performed. Increasing removal efficiencies were observed with increasing SRTs. The highest system efficiency was obtained at 20 days of SRT with COD, TN, TP removal efficiencies of 73%, 88%, and 89% respectively. The results suggested that fish processing wastewater could be significantly treated using SBR systems although it was not decreased to discharge standards. [ABSTRACT FROM AUTHOR]

A decentralized full-scale sequencing batch reactor (SBR) system for treating wastewater was operated to assess their feasibility and the response of bacterial population dynamic and nutrient removal performance. The reactor was operated under low dissolved oxygen (DO) concentration (0.3-0.7 mgL-1) and an average applied organic load of 0.5 g COD L-1 d-1 (COD: chemical oxygen demand). Removal efficiencies were higher than 70% for both soluble chemical oxygen demand and ammonium, with average effluent concentration of 51 ±15 mg COD L-1 and 16.0 mg NH4+ L-1. The mixed liquor volatile suspended solids/total suspended solids ratio was 0.9, and the average food/microorganism ratio was 0.3 g COD g VSS-1 d-1 (VSS: volatile suspended solids). The active biomass was composed of 94.9% heterotrophic and 5.1% autotrophic organisms. The most frequently identified were chemoorganoheterotrophic organisms affiliated with Bacteroidetes and Firmicutes, some of them with the capacity to denitrify and grow under low DO concentration. Temperature and sludge withdrawal were important factors in determining nitrification and phosphorus removal rates. The SBR was viable for domestic wastewater treatment and showed that the microbial community greatly influenced its performance. This work can also provide valuable insights into further applications in systems operated under low DO condition. [ABSTRACT FROM AUTHOR]

The biological removal of organic matter from a cosmetic wastewater by sequencing batch reactors has been optimized by analyzing the influence of the hydraulic retention time as well as the inclusion of anoxic and/or aerobic stages in the process sequence. Hydraulic retention time of 5 d led to the highest total organic carbon and chemical oxygen demand removal regardless the sequence used. Although a completely aerobic sequence can be used for cosmetic wastewaters treatment, the alternation of anoxic and aerobic stages significantly improved the organic matter and nutrients removal. Total organic carbon and chemical oxygen demand removal efficiencies around 67 and 74 %, respectively, were achieved with a sequence which includes two anoxic stages of one hour at the beginning and the end of the cycle. Additionally, nutrients were satisfactorily removed when anoxic stages were included along the cycle, reaching nitrogen and phosphorous removals higher than 97 and 70 %, respectively. Under these conditions the flocs showed a moderate density, good mechanical stability and settleability. [ABSTRACT FROM AUTHOR]

Antibiotic resistance gene (ARG) pollution is critical environmental problem, and horizontal gene transfer acts as a driving evolutionary force. In theory, due to the phylogenetic distance between eukaryotes and prokaryotes, eukaryotic microalgae can be a natural barrier that plays a negative role in ARG transfer among the symbiotic bacteria to decrease ARG abundance in sludge during wastewater treatment. However, this hypothesis is far from proven and needs to be tested experimentally, so this study investigated the influence of eukaryote microalgae (Scenedesmus) on the ARG profile of symbiotic bacteria based on aerobic granular reactor. The results indicated that Scenedesmus symbiosis could affect ARG diversity of bacteria, and the detected numbers of ARG in aerobic granular sludge (AG) group and algae-bacteria granular consortia (AAG) group were 45–53 and 44–47, respectively. In terms of relative abundance, after target microalgae symbiosis, the total abundance of ARGs significantly decreased from 1.17 × 10°, 2.69 × 10° and 1.36 × 10−1 to 6.53 × 10−1, 9.64 × 10−1 and 1.04 × 10−1 in the systems with the addition of streptomycin, azithromycin and vancomycin, respectively (P < 0.05), yet there was no significant difference between AG and AAG under the stress of ampicillin, sulfamethazine and tetracycline (P > 0.05). Redundancy analysis showed that the eukaryotic microalgae were significant factor explaining the change in ARG relative abundance (P < 0.05), which contributed 15.3% of ARG variation. Furthermore, the results show that, except for the tetracycline treatment system, the total relative abundances of MGEs in the AAG under the stress of the other five antibiotics were 3.54 × 10−2-7.13 × 10−1, which were all significantly lower than those in the AG (8.38 × 10−2-1.59 × 10°). There was a more significant positive correlation relationship between ARGs and mobile genetic elements (MGEs) than that between ARGs and dominated bacteria. [Display omitted] • Scenedesmus are significant factor explaining the change of ARG profile in granules. • Eukaryote microalgae addition can reduce ARG diversity in aerobic granular sludge. • Significant inhibiting role on ARG abundance is found under higher antibiotic stress. • There is significant positive correlation relationship between ARG and MGE in AAG. [ABSTRACT FROM AUTHOR]

Toxic organic dye removal from the textile wastewater is a serious concern. It is difficult to choose a single or a combination of treatment techniques between various available options; each with certain advantages and drawbacks. Six different techniques were applied on the same textile wastewater to evaluate the most effective in terms of treatment efficiency. The three most important textile wastewater quality parameters of chemical oxygen demand (COD), total suspended solids (TSS) and color were made the basis of the comparison of different treatment techniques. Other critical parameters such as treatment time, ease of operation and chemical cost employed were also considered. No single biological or physico-chemical treatment technique was found capable of removing up to 80% of the influent COD, TSS and color simultaneously from the textile wastewater. The conventional activated sludge (CAS) treatment followed by effluent polishing with the sand filtration (SF) and activated carbon adsorption columns was proved to be the most promising with COD, TSS and color removal efficiencies of 81.6%, 88.5% and 94.5% respectively. Moreover this combination of techniques enjoys lower chemical cost, medium operation time and fewer difficulties in the process control. Hence, the combination is recommended for the treatment of the textile effluents. [ABSTRACT FROM AUTHOR]

Abstract: Dairy industry wastewater is characterized by high nitrogen load and chemical oxygen demand (COD). Present study deals with treatment of simulated dairy wastewater (SDW) in terms of COD and total Kjeldahl nitrogen (TKN) removal by aerobic sequential batch reactor (SBR). SBR was optimized for various operating parameters and four phase study was carried out by varying hydraulic retention time (HRT), filling time of SDW to the reactor, anoxic phase introduction after filling phase and react phase. Kinetic study has also been performed at various HRT. Optimum HRT (HRTopt) of 1d with volume exchange ratio of 0.5 was found to sufficient to treat SDW. In view of fixing the problem of disposal of wasted activated sludge (AS) during the SBR cycle, elemental and thermo-degradation analysis of sludge was performed to understand its thermal degradation characteristics and possibility to utilize wasted AS as fuel. [Copyright &y& Elsevier]

4-nonylphenol (4-NP) is one of the most relevant endocrine-disrupting compounds that can be found in wastewaters. In this work, the effect of dosing 1 mg·L−1 of 4-NP to simulated wastewater on the activated sludge process was assessed. For it, two laboratory sequencing batch reactors (SBR) were operated for 94 days, adding 1 mg·L−1 of 4-NP to the wastewater entering one of them (SBR-NP), while the other one (SBR-B) worked as a control reactor. Holistic study of 4-NP influence on activated sludge treatment was carried out, which included both the evolution of the biomass characteristics and the effect of this substance on reactor performance. Although the COD removal efficiency in SBR-NP was lower than in the reactor without 4-NP addition (SBR-B), COD removal efficiency of SBR-NP was always higher than 90%. From day 50, nitrification bacteria were inhibited in SBR-NP and cellular viability decreased from 85.7 ± 11.0% in the first 50 days to 63.0 ± 10.2% in the last 44 days. Concerning the microbial community analysis, both Nitrosomonas and Nitrospira abundances decreased in SBR-NP (from 0.62% to 0.45%, and from 2.39% to 1.01%, respectively). Proteobacteria abundance was considerably higher in SBR-NP at the end of the experiment (44.28% in SBR-NP and 25.88% in SBR-B), which was due to increase of Aquabacterium genus (13.00% and 0.00% in SBR-NP and SBR-B, respectively), playing an important role in 4-NP degradation. Thus, 4-NP presence, in the concentrations studied, affected heterotrophic and autotrophic bacteria differently, having a negative effect in the second group. [Display omitted] • COD removal efficiency was not affected by the presence of 1 mg·L-1 of 4-NP in the feed wastewater. • Autotrophic bacteria are inhibited after 4-nonylphenol accumulation in the activated sludge. • The SBR biomass eliminated by adsorption and biodegradation the influent 4-NP. • Proteobacteria phylum increased due to presence of 4-nonylphenol. • Aquabacterium genus increased in the reactor in contact with 4-nonylphenol from 0% to 13%. [ABSTRACT FROM AUTHOR]

The study aimed to determine the polyhydroxyalkanoate (PHA) production and treatment efficiency of sequencing batch reactor (SBR) system treating synthetic domestic wastewater (DW) and synthetic domestic wastewater mixed with glycerol waste (DW+GW). The system with a total sequence of 24 h consisted of filling phase (20 min), reaction phase (22 h), settling phase (1 h), and withdrawal phase (40 min). The two-step SBR operation comprised anoxic/aerobic steps of 4/18 h was employed at reaction phase. The system fed with DW+GW produced higher PHA than the system fed with DW. In addition, PHA accumulation in activated sludge obtained from the anoxic step was higher than the aerobic step in which the highest PHA concentration and PHA yield at 1,086.87 mg/L and 61.42% as dry sludge weight, respectively, were attained. The results of treatment efficiency revealed that the anoxic step performed higher removal efficiencies of total kjeldahl nitrogen and total phosphate than the aerobic step, while an opposite result of COD removal efficiency was found. [ABSTRACT FROM AUTHOR]

The project attempt to investigate the potential of cassava starch wastewater for producing polyhydroxyalkanoate (PHA) from sequencing batch reactor (SBR) treatment system seeded with Bacillus tequilensis MSU 112, a PHA-producing bacterial strain. A total sequence of 24 h with a reaction phase (22 h) comprised anoxic/aerobic steps of 4/18 h was employed. The effect of varies chemical oxygen demand (COD) concentration of the synthetic cassava starch wastewater (CSW) (3,000 4,000 and 5,000 mg/L) on PHA production and treatment efficiency was determined. The CSW with COD at a concentration of 4,000 mg/L produced the highest PHA concentration, PHA yield, and total kjeldahl nitrogen and total phosphate removal efficiencies at 3,346 mg/L, 79.2% as dry sludge weight, 20.6% and 27.7%, respectively, while the CSW with COD concentration of 5,000 mg/L provided the highest COD removal efficiency at 94.8%. In addition, the activated sludges obtained from an anoxic phase provided higher PHA production than an aerobic phase. The results revealed that the SBR system treating CSW with the presence of B. tequilensis MSU 112 offers a promising approach for PHA production. [ABSTRACT FROM AUTHOR]

Domestic wastewater was treated by using three parallel sequencing batch reactors ( SBR) at the pH of 7. 9 - 8. 0 to optimize aeration duration of partial nitrification. The partial nitrification was achieved and maintained by controlling the aeration time of t/2, t/4, t/% respectively (t was aeration time) before appearance of "ammonia valley". Nitrite accumulation ratios were improved by 50%, 65%, 90% respectively in the three reactors which were operated in 145 days. FISH quantitative analysis showed that the percentage of ammonia oxidizing bacteria (AOB) in the reactors increased differently. AOB and nitrite oxidizing bacteria (NOB) was 3. 89% and 0. 27% of the total bacteria respectively in No. 3 reactor, which showed that AOB is the dominant bacteria in nitrifying bacteria. It is concluded that synergistic effect between the optimal control of aeration duration and the inhibition of FA would be the key factors to rapid start-up and maintain the stable nitrification. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effect of commercially available engineered iron oxide nanoparticles coated with a surfactant (ENPFe-surf) on effluent water quality from a lab-scale sequencing batch reactor as a model secondary biological wastewater treatment. Results showed that ∼8.7% of ENPFe-surf applied were present in the effluent stream. The stable presence of ENPFe-surf was confirmed by analyzing the mean particle diameter and iron concentration in the effluent. Consequently, aqueous ENPFe-surf deteriorated the effluent water quality at a statistically significant level (p < 0.05) with respect to soluble chemical oxygen demand, turbidity, and apparent color. This implied that ENPFe-surf would be introduced into environmental receptors through the treated effluent and could potentially impact them. [Copyright &y& Elsevier]

In order to investigate the biological hazard of effluents from textile industries of Fez-Boulmane region in Morocco, mutagenicity and phytotoxicity tests were performed on different biological systems. Moreover, the efficiency of a Sequencing Batch Reactor (SBR) system, working by activated sludge on a laboratory scale, was estimated by comparing the ecotoxicity results observed before and after wastewater treatment. Evaluation of the genotoxic potential was investigated by means of classic mutagenicity tests on D7 strain of Saccharomyces cerevisiae and by phytotoxicity tests on Allium sativum L., Vicia faba L. and Lactuca sativa L., estimating micronuclei presence, mitotic index and cytogenetic anomalies. The results obtained by testing untreated wastewater demonstrated major genotoxicity effects in S. cerevisiae and various levels of phytotoxicity in the three plant systems, while after SBR treatment no more ecotoxicological consequences were observed. These data confirm the effectiveness of the SBR system in removing toxic substances from textile wastewaters in Fez-Boulmane region. [Copyright &y& Elsevier]

The study involved investigating the effects of Cr(III) and the efficacy of powdered activated carbon (PAC) in reducing the inhibitory effects of Cr(III) on activated sludge under sequencing batch reactor (SBR) operation. The addition of Cr(III) into SBR system caused significant inhibitory effects on the activity of activated sludge as indicated by drastic drop in specific oxygen uptake rate (SOUR). The increase of Cr(III) concentration from 5 to 10 mg/L further deteriorated the treatment performance of SBR system in terms of the total organic carbon (TOC), suspended solids (SS) and Cr(III) removal efficiencies. With 0.167 g/L PAC (0.5 g PAC/cycle) addition into the SBR reactor influent wastewater, the TOC and Cr(III) removal efficiencies were improved from 88 to 94 % and 82 to 90 %, respectively. Coupled with the increasing mixed liquor biomass suspended solids concentration after PAC addition, the biomass apparently played the key role in the uptake of Cr(III) and kept the effluent Cr(III) concentration low. The addition of PAC was an effective way to allow continuous operation of the biological process in the presence of Cr(III) as indicated by increased SOUR as well as Cr(III) and TOC removal efficiencies. [ABSTRACT FROM AUTHOR]

Ship operations and passengers generate wastewater as part of many daily activities. Because ships move the management of these wastes, it becomes more complicated than for land-based activities. Both regulators and the public constantly focus their interest on how ships handle their wastes, and the effects they have on the environment i.e. on marine pollution. Current regulations of Annex IV of the MARPOL 73/78 Convention provide the international legal framework for the prevention of marine pollution by sewage from ships. The increasing cost of waste disposal and the tendency for more stringent environmental regulations is leading scientists to develop new technologies for the control and treatment of blackwater and graywater. This work concerns the characterization of ship-generated sewage and the development of a marine sewage treatment system based on Sequencing Batch Reactor (SBR) technology. Application of this method can result in substantial space savings. [ABSTRACT FROM AUTHOR]