Aerobic Biological Processes Research Articles

Aqueous Waste Containing AOXs: Critical Issues in Analytical Methods and Assessment of Possible Inhibitory Effects on Mesophilic and Thermophilic Aerobic Biomasses

This paper offers an in-depth review of adsorbable organic halogens (AOXs), a group of halogenated organic compounds that can be adsorbed from water onto activated carbon. AOXs are emerging contaminants derived from various industrial and household products containing active halogens. Significant concentrations of AOXs are commonly detected in wastewater originating from industries such as the paper and pulp, textile, tannery, chemical and pharmaceutical industries. The standard method for AOX determination is defined in UNI EN ISO 9562:2004. The technical literature indicates that the reliability of AOX measurements can be affected by various factors. This study investigated the possible toxicity of AOXs on wastewater treatment plants, an aspect that has received limited attention in terms of its impact on aerobic biological processes. To bridge this gap, respiratory tests were performed on different aerobic biomasses sourced from large-scale wastewater treatment facilities to evaluate potential inhibitory effects. The results underscore the importance of adopting a case-by-case approach when assessing the risks associated with these contaminants.

FOXO1 induced fatty acid oxidation in hepatic cells by targeting ALDH1L2.

Lipid metabolism disorder is the primary feature of numerous refractory chronic diseases. Fatty acid oxidation, an essential aerobic biological process, is closely related to the progression of NAFLD. The forkhead transcription factor FOXO1 has been reported to play an important role in lipid metabolism. However, the molecular mechanism through which FOXO1 regulates fatty acid oxidation remains unclear. Transcriptomic analysis was performed to examine the cellular expression profile to determine the functional role of FOXO1 in HepG2 cells with palmitic acid (PA)-induced lipid accumulation. FOXO1-binding motifs at the promoter region of aldehyde dehydrogenase 1 family member L2 (ALDH1L2) were predicted via bioinformatic analysis and confirmed via luciferase reporter assay. Overexpression of ALDH1L2 was induced to recover the impaired fatty acid oxidation in FOXO1-knockout cells. Knockout of FOXO1 aggravated lipid deposition in hepatic cells. Transcriptomic profiling revealed that knockout of FOXO1 increased the expression of genes associated with fatty acid synthesis but decreased the expression of carnitine palmitoyltransferase1a (CPT1α) and adipose triglyceride lipase (ATGL), which contribute to fatty acid oxidation. Mechanistically, FOXO1 was identified as a transcription factor of ALDH1L2. Knockout of FOXO1 significantly decreased the protein expression of ALDH1L2 and CPT1α in vitro and in vivo. Furthermore, overexpression of ALDH1L2 restored fatty acid oxidation in FOXO1-knockout cells. The findings of this study indicate that FOXO1 modulates fatty acid oxidation by targeting ALDH1L2.

Biodegradation of Photocatalytic Degradation Products of Sulfonamides: Kinetics and Identification of Intermediates.

Sulfonamides can be effectively removed from wastewater through a photocatalytic process. However, the mineralization achieved by this method is a long-term and expensive process. The effect of shortening the photocatalytic process is the partial degradation and formation of intermediates. The purpose of this study was to evaluate the sensitivity and transformation of photocatalytic reaction intermediates in aerobic biological processes. Sulfadiazine and sulfamethoxazole solutions were used in the study, which were irradiated in the presence of a TiO2-P25 catalyst. The resulting solutions were then aerated after the addition of river water or activated sludge suspension from a commercial wastewater treatment plant. The reaction kinetics were determined and fifteen products of photocatalytic degradation of sulfonamides were identified. Most of these products were further transformed in the presence of activated sludge suspension or in water taken from the river. They may have been decomposed into other organic and inorganic compounds. The formation of biologically inactive acyl derivatives was observed in the biological process. However, compounds that are more toxic to aquatic organisms than the initial drugs can also be formed. After 28 days, the sulfamethoxazole concentration in the presence of activated sludge was reduced by 66 ± 7%. Sulfadiazine was practically non-biodegradable under the conditions used. The presented results confirm the advisability of using photocatalysis as a process preceding biodegradation.

Two-stage treatment of pulp bleaching wastewater by Fenton and biological processes to remove recalcitrant pollutants

In this work, Fenton and aerobic biological processes were successfully coupled to treat pulp bleaching wastewater. The goal was to find a treatment solution to simultaneously maximise the removal of recalcitrant pollutants (adsorbable organic halides – AOX) and organic load (COD) from that wastewater. To that end, two treatment setups were studied: (i) aerobic biological process (activated sludge) followed by Fenton; and (ii) Fenton followed by aerobic biological process. Treatment by biological process followed by Fenton allowed for an overall removal of AOX and COD of 89.5 % and 82.5 %, respectively, at the optimised Fenton conditions determined by Response Surface Methodology: 489 mM H2O2, 9.3 mM Fe2+, and 49.2 min of treatment. Under the inverse treatment setup, an overall removal of 89.6 % AOX and 71.9 % COD was attained. Moreover, it was proven that the microbiological activity was not greatly affected by neither the initial organic load, nor the existence of Fenton chemicals and transformation products in the wastewater composition. Although the treatment sequence Biological → Fenton presented maximum overall performance, operating costs associated with this solution were over 2-fold higher than the inverse sequence, owing to the higher demand of chemicals.

Effect of FeCl3 concentration in chemically enhanced primary treatment on the performance of a conventional wastewater treatment plant. A case study

The effect of coagulant dosage in a chemically enhanced primary treatment (CEPT) on the performance of a conventional wastewater treatment plant (WWTP) has been investigated. Lab-scale experiments simulations were carried out in order to evaluate the effect of coagulant addition on the primary settling performance. In these experiments, FeCl3 was used as coagulant. Later, the WWTP was theoretically simulated using a commercial software (WEST®) to evaluate the effect of coagulation/flocculation on the global system, based on the results obtained at lab-scale. According to these results, the CEPT modifies the organic matter balance in the WWTP, decreasing the contribution of readily (SS) and slowly (XS) biodegradable fractions of COD to the aerobic biological process up to 27.3% and 80.8%, respectively, for a dosage of FeCl3 of 24 mg L−1. Consequently, total suspended solids in the aerobic reactor and the secondary purged sludge decreased up to 33% and 13%, respectively. However, the influence on effluent quality was negligible. On the contrary, suspended solids concentration in the sludge to be treated by anaerobic digestion increased, mainly regarding the Ss and Xs fractions, which caused an 8.1% increase in biogas production potential, with approximately 60% of CH4 concentration.

A Review of Sustainable Greywater Treatment Processes

Greywater(GW) reuse is becoming a more well-liked method of water conservation worldwide as a result of the depletion of water resources and the rise in water demand. All wastewater produced by a household, excluding sewage, is referred to as GW. The makeup of GW is different, reflecting the residents' way of life and the chemicals they use in their homes. GW flow from a household typically makes up around 65% of the total wastewater flow. Approximately 50% of the total GW is further light greywater. As a result, GW offers a great deal of possibilities for treatment, recycling, and reuse. The primary objective of this article is to study and review the literature analysis on the various properties of GW and the available treatment techniques. Technologies for treating GW can be classified as physical, chemical, biological, or as a mix of these systems. Based on the analysis the inference that, physical methods by themselves cannot provide a sufficient removal of organics, nutrients, and surfactants. Chemical approaches are successful in eliminating the suspended particles, surfactants, and organic compounds present in the low strength GW.The most practical and affordable method for recycling GW is thought to involve the use of an aerobic biological process in conjunction with physical filtering and disinfection. For collective urban housing constructions, the membrane bioreactor (MBR) appears to be a particularly attractive solution.

Study on the degradability of plastics with prodegradant additives during anaerobic and aerobic biological waste treatment processes

The degradability of conventional plastic packaging specimens made from PP and PET, that were produced with novel prodegradant additives, was investigated during biological waste treatment processes. The additives were merchandised to foster the degradation of commodity plastics by enzymatic or by abiotic processes. Four different plastic packaging specimens and two different additives were evaluated for their biodegradability during anaerobic and aerobic waste treatment conditions. Aerobic treatment was investigated in laboratory rotting tests, simulating conditions during composting in a plant according to the Austrian state-of-the-art, while anaerobic treatment was investigated in laboratory digestion reactors. The study shows that only the PET specimens showed a loss of mass of ca. 6.5%, during 50 days of digestion at 52 °C. None of the specimens degraded during the aerobic rotting process. None of the materials fragmented into microplastic particles of sizes > 1 mm under the investigated conditions. However, FTIR analysis revealed the oxidation in the case of PP specimens, which indicated a mediated oxidation process during composting, independent of the merchandised mechanism of predegradation. Under anaerobic conditions, the plastic specimens containing reactors produced more biogas within the first 20 days of digestion, that did not originate from an observable degradation of the plastics.

Localized pollution of veterinary antibiotics in watersheds receiving treated effluents from swine farms

Swine excrement is discharged into surface waters mainly as effluent in Asian countries. As swine production consumes more antibiotics and less water than humans, a mismatch of the size of swine farms and that of the rivers receiving their effluent could create severe pollution by antibiotics. However, little is known about the occurrence of antibiotics in such rivers. We therefore monitored seven veterinary drugs, six human drugs (including a metabolite), three drugs for both use (including a metabolite), and major water qualities at 30 sites in Japanese watersheds where swine outnumber humans and where their excrement is largely treated on-site by aerobic biological wastewater processes. The compositions of veterinary drugs differed substantially among sites, unlike human drugs, indicating various patterns of use among swine farms. Median concentrations at the 30 sites were <1 ng/L for seven out of the ten drugs used in livestock, whereas maximum concentrations were >1000 ng/L for three and 100–1000 ng/L for four of them, giving median–maximum among the sites of >3 log for two and 2–3 log for six of them. The spatial distribution ranges of concentrations of veterinary drugs were wider than those of human drugs (mostly <1.5 log) and other analytes (mostly <1 log), despite the correlation between those of total veterinary drugs and nitrogen, attributable to fewer swine farms than households, the intensive animal husbandry, and the various drug-use patterns among the farms. The range of maximum concentrations of veterinary drugs in the watersheds was comparable to those reported in other Asian watersheds with less strict management of swine excrement, attributable to their slow decay in conventional wastewater treatment on swine farms. Thus, attention should be paid to hot-spot pollution of antibiotics on large Asian swine farms adjacent to streams with limited dilution capacity.

Innovations for the Treatment of Effluents in the Food Industry

During the processing phases of the food business, a large amount of water is used, resulting in a large volume of effluents. Raw materials, sanitary water for food processing, transportation, cooking, dissolving, auxiliary water, cooling, cleaning, and so on are all utilized extensively in the business. Traditional anaerobic or aerobic biological wastewater treatment processes can be employed to handle organic compounds found in food sector effluent. However, some hazardous chemicals to a microbial population may be present in the effluent due to varied consumption. The effluent may contain significant levels of suspended particles, nitrogen in various chemical forms, lipids, oils, phosphorus, chlorides, and high organic content. There are traditional and well-established methods for treating effluents in the food industry, such as the coagulation-flocculation process, electrochemical processes, and biological processes, which have proven to be quite effective when used as treatment methods in a variety of industries; however, such methods have limitations. Innovative techniques, such as microbial fuel cells (MFCs), microalgae, water ultrafiltration, nanofiltration, and membrane technologies, can replace or complement traditional methods in the future. The treatment method chosen will be determined by the industry's and its wastewater's characteristics.

Molecular transformation of dissolved organic matter in refinery wastewaters: Characterized by FT-ICR MS coupled with electrospray ionization and atmospheric pressure photoionization

Dissolved organic matter (DOM) in refinery wastewater is an extremely complex mixture of various organic compounds. Using mass spectrometry, it is impossible to characterize all of the DOM molecules with only one ionization source. In this study, negative-ion, electrospray ionization (ESI), positive-ion ESI, and positive-ion atmospheric pressure photoionization (APPI) were coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to analyze the molecular composition of DOM in a refinery wastewater stream during the treatment process. There were obvious differences in the heteroatom composition, number of DOM constituents, and chemical properties in refinery wastewater under the three ionization modes. Acidic CHO and CHOS compounds detected by (−)ESI, basic CHN and CHON compounds detected by (+)ESI, and hydrocarbons detected by (+)APPI were analyzed to determine the molecular transformations that occurred during treatment. In an anaerobic biological treatment process, acidic CHO and CHOS compounds with a high oxygen content were preferentially removed, and acidic CHO and CHOS compounds with a low oxygen content were produced. In an aerobic biological process, acidic CHO and CHOS compounds with a low oxygen content were preferentially removed, and acidic CHO and CHOS compounds with a high oxygen content were produced. The whole biological treatment process has a poor removal efficiency for CHN and CHON compounds, and hydrocarbons. An activated carbon (AC) adsorption process removed different heteroatom compounds mainly with a low oxygen content for acidic and basic compounds. The transformation mechanism of CHO and CHOS compounds in the biological treatment process was analyzed by the Kendrick mass defect (KMD) theory and a mass difference network analysis. In the anaerobic process, large amounts of oxygenated CHO and CHOS compounds were degraded by decarboxylation, deoxydation, demethoxylation, and dehydration reactions, and converted to lower oxygen content compounds. In the aerobic processes, these low oxygen CHO and CHOS compounds mainly underwent carboxylation and oxidation reactions. This study determined the transformation characteristics and mechanisms of different types of organic compounds in refinery wastewater during the treatment process. The results provide guidance for the design and optimization of technologies for refinery wastewater treatment. • Molecular composition of DOM in refinery wastewater was characterized by ESI and APPI FT-ICR MS. • Transformation characteristics and mechanism of different types of compound were investigated. • Biological process could remove acidic CHO and CHOS compounds. • AC adsorption process removed various different heteroatom compounds.

Investigation, biokinetic calculation, and modelling of a real combined industrial wastewater biological treatment process by activated sludge models

Background: Treatment of combined industrial wastewater from industrial parks is one of the most complex and difficult wastewater treatment processes. Also, the accuracy of biological models for the prediction of the performance of these processes has not been sufficiently evaluated. Therefore, in this study, the International Association on Water Quality (IAWQ(-Activated Sludge Model No. 1 (ASM1) was implemented for the Jey industrial park in Isfahan province, Iran. Methods: The Jey IPWWTP process is a combination of anaerobic and aerobic biological processes. To evaluate the overall performance of IPWWTP, organic compounds, suspended solids, nutrients, attached biomass, and some operating parameters were measured during 6 months. Then, the biokinetic coefficients of aerobic processes were determined using Monod equations. Finally, the aerobic processes were modeled using ASM1 implemented in STOAT software. Results: The values of the biokinetic coefficients K, Y, Ks, Kd, and µmax were calculated as 2.7d- , 0.34 mg VSS/mg COD, 133.36 mg/L COD, 0.03d- , and 0.93d- , respectively. Based on the default coefficients and conditions of the ASM model, the difference between the experiments and model prediction was about 2 to 98%. After calibrating the ASM model, the difference between the experiments and prediction in all parameters was reduced to less than 10%. Conclusion: Investigations showed that the default coefficients and operation conditions of the ASM1 model do not have good predictability for complex industrial wastewaters and the outputs show a low accuracy compared to the experiments. After calibrating the kinetic coefficients and operating conditions, the model performance is acceptable and the predictions show a good agreement with the experiments.

Impact of saline valorization in contaminated municipal wastewater on the treatment performance and bacterial community dynamics of a membrane bioreactor

AbstractBackgroundDue to salt intrusion and the improper use of seawater for cleaning and flushing in food shops along coastal regions, the aerobic biological wastewater treatment process may have an adverse effect on treatment performance. This study demonstrates membrane bioreactor (MBR) performance for treating saline‐contaminated municipal wastewater. The aim of this study is to determine how much salt affects the efficiency of the process and how the functional bacterial community evolves in an MBR for treating actual municipal wastewater.ResultsAn MBR was applied for actual municipal wastewater treatment by increasing the NaCl concentration from 0 to 20 g L−1 with a hydraulic retention time of 12 h and complete sludge retention. High removal efficiencies of chemical oxygen demand (COD) (ranging from 80.3 to 82.8 mgL−1) and ammonium‐N (ranging from 40.8 to 44.4 mgL−1) were found at salinity concentrations of up to 7.8 ± 0.8 g L−1. However, the removal efficiency of COD was below 50% at high salinity concentrations of 17.9 ± 1.3 g L−1, whereas the removal rate of ammonium‐N had slightly changed with the value of 90%. In terms of bacterial composition, the largest dominant bacterial communities were Proteobacteria and Planctomycetota, both of which may be the predominant halotolerant/halophilic bacteria group. Additionally, Rhizobiales, Planctomycetales, Pirellulales, and Gemmatales (all of which are members of these phyla) were increased, suggesting that they played an important role in the biodegradation process.ConclusionThe MBR operation showed a good performance for treating municipal wastewater with high salinity concentrations, with a salt tolerance threshold of 7.8 g L−1. The experimental results indicate that the MBR system can be applied for treating municipal wastewater that is occasionally contaminated with seawater. © 2022 Society of Chemical Industry (SCI).

Shifts of microbial community structure along substrate concentration gradients in immobilized biomass for nitrogen removal

Immobilized biomass technology has been regarded as an effective strategy to enhance simultaneous nitrification and denitrification (SND) in existing aerobic biological wastewater treatment processes. Nevertheless, the mechanisms of SND in an aerobic immobilized biomass need to be proven. In this study, waste sludge from municipal wastewater treatment plants was immobilized by cellulose triacetate as bioplates, and an immobilized bioplate reactor (IBPR) was successfully established for nitrogen removal tests. The SND efficiency of the IBPR was increased 18% under the intermittent aeration (IA) mode compared with that under the continuous aeration (CA) mode. During IA operation, the IBPR achieved 96% COD removal and 76% NH4+-N removal, with 71% SND. The results of microbial community analysis by high-throughput sequencing showed that nitrogen-related functional bacteria were more abundant in the bioplates than in the attached biofilms. The colocalization of nitrifiers and denitrifiers in the bioplates was observed, and the microbial community of nitrogen-related functional bacteria clearly shifted with the substrate concentration gradients.

Two Novel Thermotolerant Methane Oxidizers from a Tropical Natural Gas Field in Bangladesh

Aerobic thermotolerant methane oxidizers utilize methane as a sole carbon and energy source, and predominantly they are associated with the phylum Proteobacteria. Here we present two further new strains (HGS-45: coccusshaped and HGF-47: rod-shaped and vibrioid) of thermotolerant obligate proteobacterial methanotrophic bacteria, which were isolated from an abandoned tropical natural gas field wet soil sample in the northeast of Bangladesh. Strains are Gram-negative, nonmotile, and capable of growth on methane and methanol as their energy sources. Isolates are thermotolerant and could grow up to 52oC, optimally at 42oC, but show no growth at 55 or 15oC. Based on 16S rRNA gene sequence analyses and phylogenetically, HGS-45 is most closely related to the obligate Type Ib methanotroph Methylococcus capsulatus of the family Methylococcaceae, whereas HGF-47 is affiliated to Type IIa methanotroph Methylocystis sp. of the family Methylocystaceae and possesses Type II intracytoplasmic membrane (ICM) systems. Genes of particulate methane monooxygenase (pMMO) and the methanol dehydrogenase (MDH) were detected by PCR. Southern-blot analyses of genomic DNA from both strains were positive, implying the aerobic biological oxidation process from methane to methanol by the pMMO. Each strain presumably represents a novel species. Furthermore, both strains will increase our knowledge of thermotolerant methanotrophic proteobacterial diversity, cohabitation, and their participation to global carbon cycles as well as signifying biological methane sinks in the terrestrial natural gas field ecosystems. Bangladesh J Microbiol, Volume 38, Number 2, December 2021, pp 63-71

Shrimp cracker industrial wastewater treatment with aerobic biological properties utilizing modified Contact-Stabilization method

The prawn cracker industry is one of the most common types of food industry in Indonesia. The existence of this industry has a positive impact in maintaining and improving the Indonesian economy, but it can also have a negative impact on the environment in particular, because this industry produces wastewater which can have a negative impact on the aquatic environment if the wastewater is directly discharged into the river. Based on the results of the analysis of the quality of wastewater from one of the shrimp cracker industries, it is known that wastewater contains Chemical Oxygen Demand (COD) which is 3446 mg/L, Biological Oxygen Demand (BOD) 1118.9 mg/L and acidity (pH) 5.88 – 6.13. Referring to the wastewater quality standards for the shrimp cracker industry, namely COD: 120 mg/L, BOD: 50 mg/L, and acidity pH: 6-9, the shrimp cracker industrial wastewater must be treated first before being channeled into the body. river receiving water. In this study, the treatment process used is an aerobic biological process with a modified contact-stabilization method. This method is the development of the contact-stabilization method, where in this modified method the wastewater from the treatment is recycled to the stabilization tank and together with the bacteria is transferred to the contact tank. Variations carried out in this study are the incoming wastewater flow rate (liters/hour): 4,5 ; 5.5; 6.5 ; 7.5 and 8.5 and flow rate of recycled water from treatment to stabilization tank (%) : 10 ; 20 ; 30 of the incoming wastewater flow rate. The best results were obtained at the wastewater flow rate of 5.5 liters/hour and the recycled water flow rate from the treatment to the stabilization tank 20% with a decrease in the COD value of 97.3% and BOD of 98.4% and the pH of the treated water 6.9.©2021 JNSMR UIN Walisongo. All rights reserved.

Simultaneous biodegradation of phenolics and petroleum hydrocarbons from semi-coking wastewater: Construction of bacterial consortium and their metabolic division of labor

Phenols and petroleum hydrocarbons were the main contributors to COD in semi-coking wastewater, and their removal was urgent and worthwhile. The microbial strains were selected to construct microbial community for the wastewater treatment. The concentration of phenols was decreased from 2450 ± 1.2 mg/L to 200 ± 0.9 mg/L, and the removal rate of petroleum hydrocarbons was up to 97.08 ± 0.09 % by microorganisms. After phenolic compounds with high toxicity were removed by bioaugmentation, the treated semi-coking wastewater was more biodegradable, and its water quality has been significantly improved. Through GC–MS and high-through sequencing technology, the metabolic division of labor in degradation of phenols, ring-cleavage of aromatic compounds, mineralization of metabolites was further revealed. The microbial community consisting of Pseudomonas stutzeri N2 and Rhodococcus qingshengii FF could effectively and simultaneously remove phenols and petroleum hydrocarbons, and these two strains possess great potential of being applied in aerobic biological treatment process of large-scale semi-coking wastewater.

Comparative study between biological treatment and a physicochemical treatment for the removal of Butyl Acetate in industrial residual effluents

A comparison was made between a fixed aerobic biological process and a physicochemical treatment for waste effluents with butyl acetate. An acrylic tank with 100 L capacity and a support medium for PET bottles was implemented for the formation of the biofilm and thus develop the biological reactor. In the experimental phase, concentrations of 10, 20 and 30% of butyl acetate containing sample, using hydraulic retention times of: (16, 8, 5.33 and 4 days) for each concentration. After the experimentation, a removal of 99% of COD and 97% of BOD was obtained. For the physicochemical treatment, coagulant, flocculant, and adjuvants were used, by a jar test. A decrease in 74%, 53.8%, 55%, 97% and 37%, for electrical conductivity, total suspended solids, color, turbidity, COD and BOD respectively, were obtained compared to the initial sample. Both treatments were filtered through a bed packed with activated carbon, sand, and silica gravel. The aim of this work was to evaluate / quantify butyl acetate removal efficiency in each treatment for its subsequent comparison, with prospect to the reduction of similar pollutants in residual effluents is intended.

The Application Potential of Hop Sediments from Beer Production for Composting

The chemical composition of hop sediments from beer brewing and fermentation gives them the potential for further use. These wastes are not generated in large amounts, but the absence of proper characteristics may lead to processing errors. This study examines the possibility of using hop waste for aerobic biological transformation processes (composting). The study was carried out on two hop sediments from two different technological stages of beer production: hot trub and spent hops. Chemical, microbiological, and biochemical analyses were performed in the composted hop sediments, as was the assessment of phytotoxicity to Lepidium sativum L. The tested feedstocks were partially inhabited by microorganisms and thus safe from an epidemiological point of view, and they were not a source of microbial contamination. Inhibitory properties for plant development were found for hot trub, which most likely result from the organic compound content. If it is only a small portion of its biomass, the mineral composition of hot trub does not exclude the possibility of its composting. Spent hops were characterized by a significant total nitrogen content, which affected the composting process. Composting this sediment required the selection of substrates with a widely C:N ratio.

Inhibition of the metabolism of mixed cultures of purple phototrophic bacteria by typical refinery and petrochemistry wastewater pollutants

AbstractBACKGROUNDAnaerobic treatments based on purple phototrophic bacteria (PPB) can be a more efficient and less energetically demanding alternative to aerobic biological processes currently used in refinery and petrochemistry wastewater (RPWW) treatment plants. Toxic compounds in the RPWW might compromise PPB metabolism, limiting its feasibility. In this work, seven toxic compounds that are typical components of RPWW [benzene, toluene, ethylbenzene, o‐xylene (BTEX), furfural, methyl‐di‐ethanolamine (MDEA) and butanone] were evaluated as potential inhibitors of the specific activity and growth of PPB.RESULTSInhibitory Ki parameters of 50% reduction of specific activity or biomass yield were calculated. Most of the BTEX compounds showed initial inhibitory effects on the specific activity, with Ki values of 305 ± 9, 151 ± 17 and 84 ± 2 mg L−1 for benzene, toluene and ethylbenzene, respectively. These compounds also caused inhibition of PPB growth (Ki of 411 ± 7 and 241 ± 3 mg L−1, 26% below the control, respectively). By contrast, o‐xylene affected neither the activity nor the growth. Furfural inhibited the initial specific activity (Ki of 448 ± 24 mg L−1), with no effect over the PPB growth. However, MDEA and butanone improved the initial specific activity of PPB (15% and 40% above the control, respectively). However, butanone negatively impacted the growth which decreased to ≤40% below the control.CONCLUSIONSCalculated inhibition thresholds for the seven toxic compounds were far above the actual concentrations found in the RPWW. Thus, anaerobic treatments based on PPB for the treatment of RPWW would not be limited by the presence of the toxic compounds studied here. © 2021 Society of Chemical Industry (SCI).

Occurrence and Fate of Amoxicillin and Penicillin G Antibiotics in Hospital Wastewater Treatment Plants: A Case Study - Gonbad Kavous, Iran

ABSTRACT Release of antibiotics to the environment as a result of wastewater effluent discharge is a cause for concern worldwide, as they pose a potential threat to human health and the earth ecosystem. Penicillin and amoxicillin are widely used antibiotics. Despite their rapid hydrolysis in aqueous matrices, their presence in the environment is widely investigated. The current study reported and analysed the current state of four hospital wastewater treatment plants (WWTPs) in Gonbad Kavous, Iran, during 2019, from the perspective of amoxicillin and penicillin G removals. WWTPs were sampled at various stages of the treatment process to determine at which stage the antibiotics are being removed. Concentrations of amoxicillin and penicillin G in raw wastewater, analysed by HPLC, varied from 0.35 to 1.02 and 0.02-0.31 /AgL-1, respectively. These values reduced in the final effluent, corresponding to overall efficiency in removing the studied antibiotics of 20-60.5%. Anaerobic processes (i.e. septic tank) slightly outperformed aerobic biological processes for both antibiotics' removal, and penicillin G was removed more efficiently than amoxicillin. Effects of wastewater physicochemical properties, including chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS) on antibiotics removal, were also studied. Whereas statistically significant correlations were noticed between COD, amoxicillin and penicillin G removals, their decline showed no correlation with TSS removal. Our study shows that despite the deployment of treatment plants, a considerable amount of antibiotics is released into receiving water bodies, resulting in significant amounts of these pharmaceuticals entering the environment. There is abundant room for further progress in the detection and quantification of pharmaceuticals and other emerging contaminants in hospital wastewaters and their metabolites and biodegradation products. Keywords: amoxicillin; penicillin G; high-performance liquid chromatography; hospital wastewater treatment plants; removal.