Aerobic Treatment Plant Research Articles

Factors affecting the performance of a pharmaceutical wastewater treatment plant: Characterization of effluent and environmental risk

Pharmaceutical industries produce a huge volume of emerging pollutants (EPs) that pose a threat to the aqueous environment. Biological processes have shown their inefficacy in treating many pharmaceutical products. The study assessed physicochemical parameters, EPs, heavy metals in pharmaceutical industrial wastewater, and the removal efficiency (RE) of an aerobic biological treatment plant. The study also assessed the contamination levels and risk using several indices, such as the Canadian Council of Ministers of the Environment Water Quality Index (CCME-WQI), heavy metal pollution index (HPI), heavy metal evaluation index (HEI), and risk quotients index (RQs). The study found that the treated water quality was poor, having antibiotics, nonsteroidal anti-inflammatory drugs, and others, along with several transformation products (TPs) and heavy metals, which were unsafe for consumption with high environmental risk. The analysis results showed that the RE for TSS, BOD5, COD, TDS, and EC were found to be 91.80%, 86.81%, 72.29%, 72.20%, and 65.60%, respectively, where the values of BOD5, COD, NO3−, and PO43− in the effluent were still higher than the permissible limits of the ECR (2023). However, the RE for heavy metals was in the order of Cu (84.62%) > Fe (65.04%) > Mn (63.3%) > Zn (60.58%) > Cd (53.85%) > Ni (54.12%) > Pb (42.42%) > Cr (38%), where Cr and Cd concentrations were still higher than the permissible limit of DoE (2019). The Pearson correlation and PCA suggested that EC, TDS, TSS, DO, BOD5, and COD were the most correlating and contributing variables. This study argued that metal-ligand behaviors mainly affect the removal efficiency of the treatment plant by lowering the removal rate of heavy metals and pharmaceutical products.

Integrated fate assessment of aromatic amines in aerobic sewage treatment plants

The fate and exposure of chemicals in sewage treatment plants (STPs) are major considerations in risk assessment and environmental regulation. The biodegradability and removal of seven aromatic amines were systematically evaluated using a three-tiered integrated method: a standard ready biodegradability test, an aerobic sewage treatment simulation method, and model prediction. In tier 1, the seven aromatic amines were not readily biodegraded after 28 days. In adapted aerobic active sludge, 4-isopropyl aniline, 2,4-diaminotoluene, and 4-nitroaniline among them exhibited the degradation half-life time less than 20 h, the other four aromatic amines exhibited persistent with degradation half-life of > 60 h. In tier 2 of the aerobic sewage treatment simulation testing, 2,4-diaminotoluene, 4-nitroaniline, and 4-isopropylaniline demonstrated moderately to high overall removal. Hydraulic retention time (HRT) affects the removal with the optimum HRT was determined to be 12 h to 24. 2,6-Dimethyl aniline, 2-chloro-4-nitroaniline, 2,6-diethylaniline, and 3,4-dichloroaniline were not removed during the test, indicting these four aromatic amines will enter surface water and hence pose a potential risk to aquatic ecology. Considering the lack of an STP model in China for regulation purposes, in tier 3, we developed a Chinese STP (aerobic) (abbreviated as C-STP(O)) model that reflects a universal scenario for China to predict the fate. The predicted degradation, volatilization, and absorption showed a close relationship to the physicochemical properties of the chemicals, and had same tendency with tier 2 simulation test. The prediction showed that biodegradation rather than absorption or volatilization was the main removal process of aromatic amines in aerobic STP. With the combination of modified kinetics test with C-STP (O) model, the chemical fate can be more accurately predicted than using only the readily biodegradation result.

Sustainable energy for a winery through biogas production and its utilization: A Chilean case study

The anaerobic digestion of organic residues generated from the wine production process was evaluated. Organic residues namely the stalks, pomace, vine shoots and waste-activated sludge (WAS) from the liquid waste treatment plant and wine lees were used as substrates. A physical and chemical characterization of the solid residues was carried out, demonstrating that the different residues had favorable properties for methane production, although most had acidic characteristics. It was concluded that the highest methane yields (LCH4/kg VS) were achieved in the digesters operating with wine lees and WAS from the aerobic treatment plant with values of 876 ± 45 and 690 ± 25 L CH4/kg VS for day 57 of the batch process. By contrast, the wine shoots gave the lowest methane yield achieving values of 93 ± 5 and 150 ± 6 L CH4/kg VS on days 30 and 57, respectively. An energy balance was made for the use of biogas in a wine production plant, observing that the amount of biogas generated was sufficient to supply all the necessary energy used by the production plant. An environmental analysis was also carried out focused on the emission of greenhouse gases.

Removals of Gentamicin and Benzo[a]Pyrene in an Anaerobic Multichamber Bed Reactor

The petrochemical industry wastewaters were not treated effectively due to high concentrations of Polycyclic aromatic hydrocarbon (PAH) benzo [a] pyren (BaP) and an aminoglucoside antibiotic gentamicin (GNT) in an aerobic treatment plant in Turkey. The high GNT concentration in this industry wastewater mainly originated from the toilets of the working people and from the medical care facilities since an intestinal epidemic occurrred for a period of approximately 1.5 years. The High BaP concentrations release into the wastewater originated from the high BaP production in this industry. In order to improve the biodegradability of petrochemical industry wastewaters containing excess BaP and GNT, different mixtures of BaP and GNT were biodegraded in a high rate anaerobic multichamber bed (AMCBR) reactor. The maximum anaerobic yields for 10 mg/L BaP and 1 mg/ L GNT alone were 45% and 12%, respectively. The addition of primary susbstrate increased the 200 mg/L BaP and 50 mg/ L GNT removals to 97% and 89%, respectively. BaP was biodegraded at short operation times compared to GNT. At low BaP (10-200 mg/ L) and GNT (10-35 mg/ L) concentrations, a non-competitive inhibition does not affect the binding of the substrate and KS were not affected. At high BaP (500-900 mg/ L) and GNT (75-100 mg/ L) concentrations, the BaP and GNT were biodegraded according to competitive inhibition with increased KS. BaP and GNT were biodegraded according to Haldane equations at high concentrations where they were used as the sole substrate.

Studies on optimization of naphthalene biodegradation using surface response methodology: Kinetic study and performance evaluation of a pilot scale integrated aerobic treatment plant

In the present work, the biodegradation of naphthalene (polycyclic aromatic hydrocarbon) has been studied using isolated Bacillus cereus RKS4 (MH681588.1). The process variables such as pH (5.0–9.0), temperature (25–40°C), and naphthalene concentration (10–50mg/L) have been optimized using central composite design (CCD) of response surface methodology (RSM). Analysis of variance (ANOVA) shows a high value of R2 (0.98) and confirm that the second-order regression model is in agreement with experimental data. The maximum removal of naphthalene (96.1%) were obtained at pH of 7.0, naphthalene concentration of 10mg/L, and temperature of 32.0°C. Further, the biodegradation of naphthalene was studied in a pilot-scale integrated aerobic treatment plant (IATP) at various flow rates. GC–MS analysis reveals that catechol and 2-naphthol were the major intermediate metabolites observed during biodegradation. The kinetics of naphthalene biodegradation was examined by Monod and Teissier-Edwards models and kinetic parameters were obtained to be μmax: 0.165 per day, KS: 7.91mg/L by Monod and μmax: 0.321 per day, KS: 11.5mg/L, Ki: 33.2mg/L by Teissier-Edwards.

Anaerobic Membrane Bioreactor for Urban Wastewater Valorisation: Operative Strategies and Fertigation Reuse

In European scenario, the potential source for water supply from treated wastewater is actually estimated in 1,100 Mm3/y (EU-ENV, 2015). Anaerobic processes compared with conventional aerobic ones, cause a net reduction of the operative costs and possible reuse for fertigation purposes. The tested anaerobic pilot (HRT 6 h and T 30°C) is constituted from a UASB reactor (16 L). Increment of influent organic loading rate (OLR) was studied for 1 year from 1 to 2 kgCOD/m3/d by feeding raw wastewater (Period 1), methanol (Period 2) and fermented supernatant from cellulosic sludge (Period 3).The biogas production was assessed equal to 0.13 m3biogas/kgCOD (Period 1), to 0.57 m3biogas/kgCOD (Period 2) and to 0.24 m3biogas/kgCOD (Period 3) with methane percentages constant around 33%. UASB effluent has not the final quality to comply limit values for water reuse and fertigation, especially for microbiological parameters. Further treatments could be necessary to achieve the removals of bacteria, such as E.Coli, recalcitrant organic traces and metals. Therefore, some advanced post treatments have been studied in this paper after UASB treatments, like UV disinfection, UV coupled with H2O2 and GAC adsorption. The innovative solution is coupling UASB reactor with anaerobic submerged sidestream AnMBR (UF hollow fiber membrane with 0.03 µm of nominal pore-size and 0.5 m2 of surface area KOCH, Puron single bundle). Membrane cleaning was carried out using sodium hypochlorite solution (400 ppm) each 45 days to remove organic fouling and to recover the initial permeability of the membrane. The average operative flux at process temperature was equal to 8.8±1.9 L/h/m2 and operating TMP of 44.6±8.5 mbar was detected. The removal of E.Coli was investigated in the effluent from UASB and in the permeate from AnMBR process. At clean membrane conditions, complete removal of bacteria (99±1%) was found. Furthermore, the determination of microplastics distribution was carried out both in the experimental anaerobic pilot and in the conventional full scale aerobic treatment plant. The effluent microplastics were quantified and the removal role of the different operative units was studied.

Anaerobic and aerobic sewage treatment plants in Northern India: Two years intensive evaluation and perspectives

Abstract The present study investigates the long term treatment performance of seven different sewage treatment plants located in different cities of north India for over a period of two years; two treatment technologies based on intensive aerobic processes — sequencing batch reactor (SBR) and moving bed bio-film reactor (MBBR) and; three combination of Up-flow Anaerobic Sludge Bed (UASB) reactor followed by aerobic processes — Polishing Ponds (PP), Aeration + PP and Down-flow Hanging Sponge (DHS). Effluent quality was not in accordance to the surface water disposal standards, Ministry of Environment, Forest and Climate Change Govt. of India, for UASB followed by PP and by Aeration +PP. However, a high effluent quality was observed in UASB followed by DHS; SBR and MBBR systems. In the last cases, NH4-N and PO4-P removal was higher than 85 and 60%, respectively; with a final effluent concentration of 20 mg BOD5/L, 50 mg COD/L, 20 mg TSS/L, 10 mg NH4-N/L and 5 mg PO4-P/L. Although strictly intensive aerobic systems showed a better performance, UASB followed by simple aerobic systems, such as the DHS process is a promising technology, especially in India to reach required BOD level for water reuse at low costs.

Methane emissions from anaerobic sludge digesters in Mexico: On-site determination vs. IPCC Tier 1 method

Wastewater treatment is an important source of methane (CH4) emissions. In most large-size aerobic treatment plants, the excess sludge is digested in anaerobic reactors (AD), with the concomitant CH4 emissions. The guidelines of the Intergovernmental Panel on Climate Change (IPCC) have been adopted worldwide for quantifying the national emission inventories, which include wastewater treatment plants (WWTP) as a key category. The IPCC recommends using default emission factors (Tier 1) for countries with limited available data (such as Mexico and most developing countries). However, these estimates have a high degree of uncertainty, owing to the lack of reliable information about the operation process and local environmental conditions. In order to reduce uncertainty in the estimation of CH4 emission from WWTP in Mexico, a country-specific emission factor was determined for AD associated with activated sludge process. This was accomplished with on-site data obtained from the AD of six activated sludge WWTP. In addition, the measured CH4 emissions were compared to those resulting from the application of the IPCC Tier 1 method, using the recommended default methane correction factor (MCF: 0.8) as well as alternate values (0.32 and 0.26) recently proposed by the authors. Results show that the IPCC Tier 1 method, using the recommended MCF, highly overestimate CH4 emissions compared with the values obtained on-site. In contrast, the alternate MCF achieved better estimations than the IPCC-recommended MCF, much closer to the observed emission values. The CH4 emission factor proposed as country (Mexico) specific value is 0.49 kg CH4/kg BODrem, which would allow the application of IPCC Tier 2 method. By doing so, the uncertainty associated with CH4 emission from aerobic treatment plants with AD would be reduced. This, in turn, would provide important information for implementing appropriate CH4 mitigation strategies for the water sector.

Methane correction factors for estimating emissions from aerobic wastewater treatment facilities based on field data in Mexico and on literature review

Wastewater treatment (WWT) may be an important source of methane (CH4), a greenhouse gas with significant global warming potential. Sources of CH4 emissions from WWT facilities can be found in the water and in the sludge process lines. Among the methodologies for estimating CH4 emissions inventories from WWT, the more adopted are the guidelines of the Intergovernmental Panel on Climate Change (IPCC), which recommends default emission factors (Tier 1) depending on WWT systems. Recent published results show that well managed treatment facilities may emit CH4, due to dissolved CH4 in the influent wastewater; in addition, biological nutrient removal also will produce this gas in the anaerobic (or anoxic) steps. However, none of these elements is considered in the current IPCC guidelines. The aim of this work is to propose modified (and new) methane correction factors (MCF) regarding the current Tier 1 IPCC guidelines for CH4 emissions from aerobic treatment systems, with and without anaerobic sludge digesters, focusing on intertropical countries. The modifications are supported on in situ assessment of fugitive CH4 emissions in two facilities in Mexico and on relevant literature data. In the case of well-managed centralized aerobic treatment plant, a MCF of 0.06 (instead of the current 0.0) is proposed, considering that the assumption of a CH4-neutral treatment facility, as established in the IPCC methodology, is not supported. Similarly, a MCF of 0.08 is proposed for biological nutrient removal processes, being a new entry in the guidelines. Finally, a one-step straightforward calculation is proposed for centralized aerobic treatment plants with anaerobic digesters that avoids confusion when selecting the appropriate default MCF based on the Tier 1 IPCC guidelines.

RECENT STATE-OF-THE-ART LEACHATE TREATMENT PLANTS IN EASTERN ENGLAND

The paper presents detailed design and performance data for two full-scale leachate treatment plants that have been designed and operated in Eastern England during recent years, in which reliable performance has been achieved for an extended period. The first plant is a modified Sequencing Batch Reactor system, treating relatively diluted leachate (COD about 500 mg/l, ammoniacal-N about 180 mg/l) from a closed landfill site, to provide complete nitrification of ammoniacal-N and degradation of all degradable COD, in a manner requiring minimal site attendance. This is made possible by means of reliable and robust operational software, which can run the plant in a completely automated manner, but nevertheless alerts the operator to any issues. The second state-of-the-art leachate treatment plant was designed and built at the Masons Landfill Site in Ipswich. It was designed to treat 160 m 3 /day of strong methanogenic leachate, often containing more than 2000 mg/l of ammoniacal-N. Discharge of treated leachate is to sewer, under a consent in which the main parameters that are limited are ammoniacal nitrogen, and COD. Treatment comprises full biological nitrification, with ultra-filtration membranes providing additional removal of COD, to achieve challenging consent limits. Taken together, the two case studies provide valuable, robust and real, full-scale data, for the degree of treatment which can realistically be delivered, by well-designed and operated, aerobic biological leachate treatment plants, where each plant has succeeded in treating leachates to well below the consented quality limits for discharge.

Performance Assessment of Moratuwa- Ratmalana Biological Nutrient Removal Industrial Wastewater Treatment Plant

This study evaluates the performance of Moratuwa-Ratmalana Biological Nutrient Removal (BNR) plant during the dry period of 2016. This treatment plant is 1st ever reverse A2/O (anoxic/ anaerobic/ aerobic) treatment plant in Sri Lanka which was established by the National Water and Drainage Board (NWDB) in 2013. This study was confined to the dry period. This study was carried out to achieve two objectives. First objective is to monitor and evaluate the overall efficiency of the treatment plant in terms of removing pollutants from the influent. Second objective is to analyze nitrogen and phosphorous removing ability in each compartment. Samples were collected weekly for a stretch of 15 weeks from February to May. The sampling method utilized in this study was ‘grab sampling’ and ‘composite sampling’. First samples from each three layers of each of the three compartments were collected through grab sampling and then composite samples for each layer was prepared by using the grab samples. Composite samples were used for final testing. In addition samples were also collected for influent and effluent from the composite sampler which is located in the treatment plant. The analysis was carried out to test for physical (pH, Temperature) and chemical (BOD, COD, TSS, TP, TN) parameters of each collected sample. The performance evaluation has indicated that 88.52% COD removal, 97.05% TSS removal, 94.12% BOD removal, 84.23% of TP removal and 81.65% of TN removal efficiencies have been achieved. Also the analytical measurements obtained of the treated effluent are compatible with the discharge water quality standards issued by CEA, Sri Lanka. In addition it was shown that each compartment of the treatment plant meets the design expectations regarding Nitrogen and Phosphorous removing abilities. Keywords: Wastewater Treatment, Plant performance, Reverse A2/O

Evaluation of B. cereus MTCC 25641 for the Treatment of Dairy Waste Effluent

Dairy is one of the industries producing wastewater rich in organic matter and thus leading to creation of odorous and high COD containing effluent. Biotreatment leading to bioconversion of the waste materials is probably the most cost-effective technique for managing and utilizing waste. A pilot-scale aerobic treatment plant showing air pressure of 6 kg/cm3 was designed keeping all the conditions similar to the main aerobic plant of any dairy plant. The COD (Chemical Oxygen Demand) of the control effluent i.e., without aeration, decreased from 588.5 mg/L on the first day to 147.75 mg/L on the seventh day while the effluent inoculated with B. cereus MTCC 25641 decreased the COD load from 588.5 mg/L on the first day to 38.75 mg/L on the seventh day, which shows that a pilot plant B. cereus MTCC 25641 showed excellent results as 50.68% COD and 44.07% BOD (Biochemical Oxygen Demand) reduction, while pH increased from 6.7 to 8.54 along with 44.06% increase in TDS (Total Dissolved solids) was seen after 24h of aeration.

Assessment of pesticides removal using two-stage Integrated Aerobic Treatment Plant (IATP) by Bacillus sp. isolated from agricultural field

The biodegradation of synthetic wastewater containing Atrazine, Malathion and Parathion was studied in two stage Integrated Aerobic Treatment Plant using Bacillus sp. (consortia) isolated from agricultural field. The influent stream containing these pesticides with initial COD of 1232mg/L were fed to first reactor and treated effluent of first reactor was fed to second reactor. The maximum removal of pesticides in IATP was found to be greater than 90%. The various process parameters such as pH, DO, Redox potential and BOD5/COD were monitored during the treatment. The degradation of pesticides and its metabolites in the treated effluent were confirmed by GC–MS. Kinetic parameters such as first order rate constant (Kobs), cell yield (YX/C) and decay coefficients (Kdp) were evaluated and found to be 0.00425 per hr, 0.696mg of COD/mg MLSS and 0.0010 per hr respectively. This integrated process was found more effective than physico-chemical treatment of pesticides.

Efficiency assessment of aerobic biological effluent treatment plant treating pharmaceutical effluents

The present paper undertakes a study of the physico-chemical properties and toxic heavy metals content in the untreated and treated pharmaceutical effluents in order to evaluate the working efficiency of industrial effluent treatment plants. The treatment efficiency achieved for various parameters was conductivity (79.94%), alkalinity (93.91%), hardness (87.70%), chloride (89.24%), cyanide (79.66%), phosphate (99.19%), total dissolved solids (85.89%), total suspended solids (96.87%), salinity (52.41%), dissolved oxygen (27.32%), biochemical oxygen demand (83.39%) and chemical oxygen demand (72.21%). The removal efficiency achieved for different heavy metals was Cu2+ (79.66%), Ni2+ (69.22%), Cr6+ (80.15%), Pb2+ (72.14%), Fe3+ (92.59%) and Zn2+ (90.61%). The level of biochemical oxygen demand (64 mg L−1) in the treated effluents was above the limit of 30.0 mg L−1, chemical oxygen demand level (208 mg L−1) was close to a limit of 250 mg L−1, while average Pb2+ concentration (0.10 mg L−1) was on the borderline of maximum permissible limit of 0.10 mg L−1 set by Central Pollution Control Board for safe discharge of industrial effluent in inland surface water. The average concentration of cyanide (0.01 mg L−1) in the treated industrial effluent of our study is of great concern to the fisheries of freshwater ecosystem in which the effluents finally get discharged. Based on the results of the present study, it is concluded that the pollution level in the discharged pharmaceutical effluent is of the great concern requiring proper treatment and regular scientific monitoring so as to protect the environmental degradation of water resources and facilitate the propagation of the aquatic life.

Evaluation of treatment potential, biogas generation and sludge properties of an anaerobic claridigester

The anaerobic process for the treatment of municipal and industrial wastewater has been in practice for over a century. Apart from treatment of wastewater, the process has the advantage of lower sludge and biogas production that can save energy. Application of this process in a primary clarifier in such a way that there is simultaneous digestion of primary settled sludge and organic removal from wastewater can be more advantageous in an aerobic treatment plant. The paper discusses the performance of such a primary claridigester at ambient temperature. With a single hydraulic retention time (HRT) of 4.5 h, the organic (chemical oxygen demand (COD) and biochemical oxygen demand (BOD)) removal efficiency was 36.3% and 34.6%, respectively. The biosolid production rate was 0.383 g VSS/g COD removed or 0.818 g VSS/g BOD3 removed. However, biogas contains 80.8% methane and the COD mass balance revealed the loss of removed COD as 41.5% in the form of dissolved effluent from the claridigester. On account of sludge characterization, it was observed that nitrogen and zinc were present in highest concentration (2.55% and 1,776 mg/kg dry solids) and other nutrient and heavy metal parameters were within limits of not posing any risk of soil toxicity if disposed of for enrichment of soil.

Odor compounds released from different zones of two adjacent waste treatment facilities: Interactive influence and source identification

An integrated approach was applied to identify the key odorants comprising emissions from different zones in two adjacent waste treatment facilities (an aerobic biological treatment plant and an anaerobic landfill site), identify their precise sources, and distinguish the interactive influences between them. Seven odor families were investigated, including alcohols, terpenes, carbonyls, aromatics, volatile fatty acids (VFAs), sulfur compounds, and ammonia. Principal components analysis, characteristic molecular ratios, and ternary diagrams were used to differentiate the interactive influence of the odor sources. Among typical biotic compounds, terpenes were found to be more suitable as odor markers for their better fingerprinting character than sulfur compounds and VFAs. Ratios of p-cymene at sampling locations related to the biological treatment plant (aerobic status) were between 0.00 and 0.25, whereas those at landfill-related sampling points (anaerobic status) were between 0.25 and 1.0. The molecular ratio of terpenes was also found to be an appropriate means to differentiate between homologous and similar odor sources such as an aerobic biological treatment plant and anaerobic landfill.Implications: The aim of this work is to identify the key odorants comprising emissions from different zones in two adjacent waste treatment facilities, identify their precise sources, and distinguish the interactive influences between them. The emission of gaseous pollutants greatly affects the living quality of nearby residents, and odor complaints are becoming a major problem. In this study we utilized various pretreatment and analytical methods to obtain integrated emission information of gaseous pollutants. The results showed terpenes were found to be more suitable as odor markers for their better fingerprinting character than sulfur compounds and VFAs.

Acid production as a Limiting Factor during the Aerobic Biological PreTreatment of Confectionary Wastewaters

The treatment of confectionary wastewaters by a biological aerobic treatment plant encountered strong failures when wastewaters concentration exceeded 30 g/l of chemical oxygen demand (COD), although the COD inlet flow remained under design specifications. Treatment performances stayed under 50%, and strong acid production and Hydrogen potential drop lead to heavy corrosion of equipments. During a laboratory scale study using the same organic load, with residence times ranging from 1 to 15 days, Hydrogen potential (pH) drop proved to be caused mainly by aerobic production of organic acids from sugars, leading thus to an auto-inhibiting process. The study demonstrated the influence of pH, acids and aeration rate upon key parameters as respiration rates and degradation kinetics. A reduction of 30 to 35 g/l of COD was obtained in laboratory scale reactors with pH and oxygen control. A comparison between the laboratory scale reactors and the full scale plant was made by measuring in the reactors the clean water oxygenation transfer rates and comparing its values to the data issuing from the plant. Compared to the data issuing from the full-scale wastewater treatment plant, the results of this study allowed giving recommendations for its upgrade.

Micropollutants removal in an anaerobic membrane bioreactor and in an aerobic conventional treatment plant

The paper expresses an attempt to tackle the problem due to the presence of micropollutants in wastewater which may be able to disrupt the endocrine system of some organisms. These kinds of compounds are ubiquitously present in municipal wastewater treatment plant (WWTP) effluents. The aim of this paper is to compare the fate of the alkylphenols-APs (4-(tert-octyl)) phenol, t-nonylphenol and 4-p-nonylphenol and the hormones (estrone, 17β-estradiol and 17α-ethinylestradiol) in a submerged anaerobic membrane bioreactor (SAMBR) pilot plant and in a conventional activated sludge wastewater treatment plant (CTP). The obtained results are also compared with the results obtained in a previous study carried out in an aerobic MBR pilot plant. The results showed that the APs soluble concentrations in the SAMBR effluent were always significantly higher than the CTP ones. Moreover, the analyses of the suspended fraction revealed that the AP concentrations in the SAMBR reactor were usually higher than in the CTP reactor, indicating that under anaerobic conditions the APs were accumulated in the digested sludge. The aerobic conditions maintained both in the CTP system and in the aerobic MBR favoured the APs and hormones degradation, and gave rise to lower concentrations in the effluent and in the reactor of these systems. Furthermore, the results also indicated that the degradation of APs under aerobic conditions was enhanced working at high solid retention time (SRT) and hydraulic retention time (HRT) values.

Removal of oxytetracycline (OTC) in a synthetic pharmaceutical wastewater by sequential anaerobic multichamber bed reactor (AMCBR)/completely stirred tank reactor (CSTR) system: biodegradation and inhibition kinetics

AbstractBACKGROUND: The antibiotics in industrial and munipical wastewaters could not be removed effectively in conventional anaerobic and aerobic biological treatment plants. Few studies have been performed to investigate the biodegradation and inhibition kinetics of oxytetracycline (OTC) on methanogens and total volatile fatty acids (TVFA).RESULTS: A high rate anaerobic multichamber bed reactor (AMCBR) was effective in removing the molasses‐chemical oxygen demand (COD), and the OTC antibiotic with yields as high as 96% at an influent OTC loading rate of 133.33 gOTC m−3 day−1 at a hydraulic retention time (HRT) of 2.25 days. Increasing the OTC loading rates from 22.22 gOTC m−3 day−1 to 133.33 gOTC m−3 day−1 improved both hydrolysis and specific utilization of molasses‐COD. The inhibition constants of TVFA (KI−TVFA−meth) and OTC (KI−OTC−meth) on methanogens decreased at OTC loadings > 133.33 gOTC m−3 day−1. The direct effect of OTC loadings > 133.3 gOTC m−3 day−1 on acidogens and methanogens was evaluated using the Haldane inhibition kinetic.CONCLUSION: OTC antibiotic was effectively removed in a sequential AMCBR/completely stirred tank reactor (CSTR). The Haldane inhibition constant (KID) decreased significantly at high OTC loads indicating the increase in toxicity. Copyright © 2012 Society of Chemical Industry

Reuse of anaerobically and aerobically pre-treated textile wastewater by UF and NF membranes

The aim of this study is to compare different pre-treatment techniques before the use of UF and NF membranes for textile industry effluents. Three different applications are discussed. First, raw textile wastewater effluent was applied to membranes (direct filtration of raw wastewater). After that, aerobically (full scale aerobic treatment plant (SBR) effluent that is present in the factory) and anaerobically (laboratory scale anaerobic treatment plant effluent) pre-treated effluents were compared with UF and NF membranes. UF and/or NF experiments were carried out at the laboratory scale and investigated at different operating pressures. The study showed that aerobic pre-treatment gave better performance prior to membrane filtration, and NF treatment with UF pre-treatment was the most suitable option for the effluents, as determined by different standards of permeate quality and quantity for different purposes in factories.