Removal In Wastewater Treatment Plants Research Articles

Unraveling microplastics removal in wastewater treatment plant: A comparative study of two wastewater treatment plants in Thailand

Wastewater treatment plants (WWTPs) are considered as a problematic pathway for microplastics (MPs) entering the oceans. This study compares the efficiency of MP removal in two different WWTPs (A1 and A2) with a conventional treatment system located in Bangkok, Thailand. WWTP-A2 is equipped with a pilot-scale ultrafiltration (UF) as a final polishing step. The number of MPs in the influent entering A1 and A2 was 16.55 ± 9.92 and 77.00 ± 7.21 MP/L, respectively. The average of 3.52 ± 1.43 and 10.67 ± 3.51 particles per L was found in the effluent discharged from A1 and A2, respectively, to nearby canals. The removal efficiency of WWTP-A2 built as a closed underground system was shown to be up to 86.14% which is more efficient than the conventional WWTP (A1). MPs were subsequently removed by a UF unit which resulted in a removal efficiency of 96.97%. However, when a large volume of treated wastewater volume is considered, a high concentration of MPs is discharged daily with the final effluent if the efficiency remains the same. The size fraction of 0.5–0.05 mm contributed to the largest proportion of MPs, and fibers were detected as the dominant group at both study sites. Results from a Fourier Transform Infrared Spectroscopy (FT-IR) confirmed that most fibers were polyethylene terephthalate (PET) derived from clothes. MPs retained in the sludge ranged from 2.63 × 104 to 4.74 × 104 particles per kilogram of dry sludge. A significant number of MPs can spread further to the environment by soil application. The results of the study indicate that the design of WWTPs and the addition of advanced tertiary treatment can improve MP removal efficiency of a WWTP. Moreover, the absence of a primary sedimentation tank in both treatment plants may influence the removal efficiency.

Effect of chemical structure on the microbial nitrification inhibition and copper corrosion inhibition properties of azole compounds

Azoles are a class of nitrogen-containing heterocyclic compounds that are widely used as metal corrosion inhibitors in different industrial processes and consumer products. These compounds are severely inhibitory towards microorganisms responsible for nitrification and can impair the efficiency of biological nitrogen removal in wastewater treatment plants. This study assessed the effect of chemical structure on the toxicity of simple azole compounds towards microbial nitrification with the aim of identifying substitution patterns leading to decreased inhibition. Nitrification inhibition by the widely used azoles, pyrazole and 1,2,4-triazole, and several of their derivatives with dimethyl-, diethyl-, carbonyl-, amino substituent groups was studied. The results indicated that, while pyrazole and 1,2,4-triazole were severely inhibitory towards nitrification, addition of dimethyl- and diethyl-substituents greatly lowered the toxicity response of these compounds. The fifty percent inhibition concentrations (IC50) of pyrazole and 1,2,4-triazole were very low, 0.07 and 0.11 mg L−1, respectively, indicating a high level of inhibition. In contrast, nitrification inhibition by the dimethyl- and diethyl-substituted azoles was at least 30–700 times lower compared to the unsubstituted parent compounds, and in the best case, 3,5-diethyltriazole was found to be completely non-toxic. Preliminary evaluation of the corrosion inhibition efficiency of the alkyl-substituted azole compounds under alkaline conditions was conducted electrochemically. All the azoles tested were able to inhibit copper corrosion to a significant extent. For the pyrazoles, the corrosion inhibition performance improved with the addition of dimethyl- and diethyl-substituents. The inhibition efficiency by pyrazole, 3,5-dimethylpyrazole and 3,5-diethylpyrazole was 71.5, 77.6 and 85.0%, respectively, with respect to the control with no inhibitor. In the case of triazoles, the corrosion inhibition efficiency was slightly lower for the alkyl-substituted triazoles (77.7% for 3,5-dimethyl-1,2,4-triazole and 82.9% for 3,5-diethyl-1,2,4-triazole) than for the unsubstituted 1,2,4-triazole (89.6%). An important implication of these results is the possibility of replacing conventional azole compounds by their non-toxic substituted counterparts in industrial applications. This would prevent inhibition of microbial nitrification without compromising the efficacy of the azoles as inhibitors of copper corrosion.

Understanding the effects of sludge characteristics on the biosorption of triclosan

On account of hydrophobic nature, the adsorption process on solids is considered as the major pathway for triclosan (TCS) removal in wastewater treatment plants. In this work, four sludge sources (primary sludge, thickened sludge, dewatered sludge, and anaerobic digested sludge) were collected to evaluate the adsorption performance of TCS. The solid-liquid distribution coefficients of TCS were increased with total solids increasing of primary sludge, thickened sludge, and dewatered sludge, whereas decreased in anaerobic digested sludge. Results further revealed differences in sludge floc sub-structures of TCS adsorption. The residues contained most of adsorbed TCS in all sub-structures, while distinguished in various extracellular polymeric substances (EPS). The major contributor of EPS sub-fractions to TCS adsorption was identified as tightly bound EPS in thickened sludge and soluble EPS in anaerobic digested sludge. Based on the excitation-emission matrix spectra and Fourier infrared spectrum results, the protein-like and humic acid-like substances were closely related to the TCS adsorption, and hydrogen bond, hydrophobic interaction, and electrostatic interaction were considered as the dominant mechanisms. This study comprehensively reveals the effects of sludge sources and sub-structures on TCS adsorption, which improves the understanding of interaction and migration processes between TCS and sludge.

Microplastic- An Imposing Commination to the Aquatic Ecosystem and its Removal Strategies in Wastewater Treatment Plants: A Systematic Review

Plastic is broadly used for various human interests (technological devices, food packaging, medical products, etc.) and there is an increasing concern about the risks for our surrounding environment and health. In particular, microplastics (MPs), both primary and secondary, occur in all environmental pockets and constitute a potential warning, since they easily enter into the food chain. Moreover, microplastics have the ability to absorb diverse pollutants, which thereby get accumulated inside human body via processes of bioaccumulation and biomagnification. A systematic review was conducted to determine the effectiveness of wastewater treatment facilities (WWTPs) in removing microplastics. Published research on the effectiveness of wastewater treatment plants (WWTPs) for microplastic removal were searched using international databases (PubMed, Science Direct, and Scopus). Contamination of MPs in aquatic environment has presently been recorded as a transpiring environmental threat because of their fatalistic impact on the ecosystem. Their sources are numerous, but, undoubtedly, all are from synthetic matters. The sources of MPs are cosmetics and products of personal care, textile and tyre, abrasion processes of some other plastic products, bitumen and paints for road marking. Due to their low density and tiny particle size, MPs get easily extravasated into the wastewater drainage systems. Therefore, the municipal wastewater treatment plants (WWTPs) are designated to be the foremost recipients of MPs prior to getting excreted into the natural water reservoirs. The focus of this article is to put forward an all-inclusive review in order to preferably understand the channels of MPs into the environment, their characteristics in wastewater, and most importantly, the removal efficiency of MPs of the subsisting wastewater treatment technologies, as arrogated by the WWTPs. This review also encompasses the expansion of budding microplastics treatment technologies that have been investigated till date. Then, in the not-too-distant future, effective and standardised techniques for measuring MPs should be developed, as well as a greater understanding of sources and strategies for reducing microplastics contamination of treated effluent.

Spatiotemporal variation and removal of selected endocrine-disrupting chemicals in wastewater treatment plants across China: Treatment process comparison

In this study, the spatiotemporal variation in the occurrence of 19 endocrine-disrupting chemicals (EDCs) spanning four seasons in wastewater treatment plants (WWTPs) located in 17 Chinese cities was investigated. Removal efficiencies for selected EDCs in 17 WWTPs over four seasons were analyzed. Contributions of conventional and advanced process segments to the removal efficiency of EDCs were explored, which compared the removal efficacies of a variety of secondary and advanced processes for EDCs. Results showed that EDCs were extensively detected in WWTPs, with bisphenol A (BPA), dehydroepiandrosterone (DHRD), androstenedione (ADD), and pregnanediol (PD) being dominant in excess sludge and wastewater. Seasonally, the greatest seasonal differences were observed in the influent, with the concentrations of 12 EDCs varying significantly between seasons. Spatially, concentrations of BPA, DHRD, testosterone (TTR), and estriol (E3) in the influent significantly varied between the northern and southern WWTPs. Fourteen EDCs were removed steadily among the four seasons, while most EDCs had considerable removal differences between WWTPs. Contribution of the conventional process segment to the removal of individual EDCs was higher than that of the advanced process segment in WWTPs. Quantitative meta-analysis indicated that the anaerobic-anoxic-anaerobic (AAO) process in the various secondary processes had the highest removal of the target EDCs. Mass balance analysis further suggested that biodegradation in the aerobic tank of the AAO process was the major pathway for most EDCs removal. This study systematically depicts the spatiotemporal distribution of EDCs in WWTPs located across China and deepens the comprehension of EDCs removal in Chinese WWTPs from a treatment process perspective.

Micro- and nanoplastics removal mechanisms in wastewater treatment plants: A review

In recent years, the intensification in environmental pollution with micro and nano-plastics (MNPs) has become a global environmental concern. MNPs are some of the emerging contaminants that appear as new challenges to the scientific community because of their adverse effect on human health and environment. Conventional wastewater treatment plants (WWTPs) can efficiently remove the MNPs from the wastewater. The reduction of MNPs from WWTPs has attracted much attention in the past decades. Despite the efficient removal, WWTPs are considered one of the key routes through which MNPs have been introduced to the environment, through the large volumes of effluent continually released to the water bodies. Therefore, a detailed understanding of the behavior of MNPs and their removal mechanisms in WWTPs is highly essential. Nevertheless, an inclusive review of the MNPs treatment techniques in WWTPs is infrequent. So, we review the treatment processes presently employed for MNPs removal in WWTPs to upgrade the existing designs further. In addition, the effectiveness of advanced treatment processes, such as membrane technologies, advanced oxidation process, electro-coagulation, nano technology, etc., in eliminating MNPs are presented and discussed. However, possible toxic microbial biotransformation of MNPs during biological treatment steps in WWTPs needs to be taken care of via further in-depth research. As a basic knowledge of removal mechanisms in WWTPs could reduce the environmental pervasiveness of MNPs, this review is likely to offer helpful information in establishing an efficient approach to control and minimize environmental pollution from MNPs.

Comparative analysis of the removal and transformation of 10 typical pharmaceutical and personal care products in secondary treatment of sewage: A case study of two biological treatment processes

To reduce the occurrence of PPCPs in the environment, its removal in wastewater treatment plants (WWTPs) has attracted much attention. This study reported the removal characteristics of 10 typical PPCPs in two biological treatment processes: blast aeration and UNITANK. The results demonstrated that caffeine (CAF), bezafibrate (BZB), gemfibrozil (GFB), metoprolol (MET), sulfamethoxazole (SMX), and sulfamerazine (SMZ) were mainly removed through biodegradation. Among them, the removal efficiency of CAF was the largest (>85%), and MET was the lowest (<30%). Sulfadiazine (SDZ), naproxen (NPX), sulpiride (SUL), and ofloxacin (OFX) were removed through the combined effect of biodegradation and sludge adsorption. During biotransformation of sulfonamides (SAs), MET, and SUL, some of the conjugates were decomposed into their parent forms again. The results revealed that the adsorption of drugs was correlated with octanol-water partition coefficient (Kow) and electrostatic interaction. The biodegradation efficiency was affected by oxygen supply conditions. The facultative environment, longer sludge retention time (SRT) and hydraulic retention time (HRT) were positively correlated with the removal of most drugs (CAF, SUL, GFB, MET, NPX, OFX, SDZ, SMX). This paper summarized the similarities and differences of drugs’ removal characteristics under different processes and wish to provide useful suggestion for the removal technology of PPCPs in WWTP.

Efficacy of Ciprofloxacin and Amoxicillin Removal and the Effect on the Biochemical Composition of Chlorella vulgaris.

Antibiotics are frequently detected in the aquatic environment due to their excessive usage and low-efficiency removal in wastewater treatment plants. This can provide the origin to the development of antibiotic-resistant genes in the microbial community, with considerable ecotoxicity to the environment. Among the antibiotics, the occurrence of ciprofloxacin (CIP) and amoxicillin (AMX) has been detected in various water matrices at different concentrations around the Earth. They are designated as emerging contaminants (ECs). Microalga Chlorella vulgaris (C. vulgaris) has been extensively employed in phycoremediation studies for its acclimatization property, non-target organisms for antibiotics, and the production of value-added bioproducts utilizing the nutrients from the wastewater. In this study, C. vulgaris medium was spiked with 5 mg/L of CIP and AMX, and investigated for its growth-stimulating effects, antibiotic removal capabilities, and its effects on the biochemical composition of algal cells compared to the control medium for 7 days. The results demonstrated that C. vulgaris adapted the antibiotic spiked medium and removed CIP (37 ± 2%) and AMX (25 ± 3%), respectively. The operating mechanisms were bioadsorption, followed by bioaccumulation, and biodegradation, with an increase in cell density up to 46 ± 3% (CIP) and 36 ± 4% (AMX), compared to the control medium. Further investigations revealed that, in the CIP stress-induced algal medium, an increase in major photosynthetic pigment chlorophyll-a (30%) and biochemical composition (lipids (50%), carbohydrates (32%), and proteins (65%)) was observed, respectively, compared to the control medium. In the AMX stress-induced algal medium, increases in chlorophyll-a (22%), lipids (46%), carbohydrates (45%), and proteins (49%) production were observed compared to the control medium. Comparing the two different stress conditions and considering that CIP is more toxic than AMX, this study provided insights on the photosynthetic activity and biochemical composition of C. vulgaris during the stress conditions and the response of algae towards the specific antibiotic stress. The current study confirmed the ability of C. vulgaris to adapt, bioadsorb, bioaccumulate, and biodegrade emerging contaminants. Moreover, the results showed that C. vulgaris is not only able to remove CIP and AMX from the medium but also can increase the production of valuable biomass usable in the production of various bioproducts.

UNISON decision framework for hybrid optimization of wastewater treatment and recycle for Industry 3.5 and cleaner semiconductor manufacturing

Semiconductor manufacturing is water-intensive that generates tremendous wastewater during the wafer cleaning for lengthy wafer fabrication processes. In particular, the effluent discharged from wafer cleaning processes contains a huge amount of hydrogen peroxide. The high concentration of hydrogen peroxide will affect the yields of the efficiency of the wastewater treatment plant and cause the environmental risk of pollution. Catalase has been employed in the pre-treatment process of wastewater treatment plants for hydrogen peroxide removal. The pre-treatment process includes multiple pumps for catalase emission adjustment. The oversupply of catalase may lead to the extra cost of the company, while the insufficient quantity of the catalase will cause the risk of environmental contamination, and the adjustment of hydrogen peroxide concentration is not real time. To address realistic needs, this study aims to develop a UNISON framework for hybrid optimization to minimize the potential risk of the hydrogen peroxide wastewater treatment while considering the uncertainty for forecasting the wastewater treatment demands for Industry 3.5. In particular, the proposed framework includes the hydrogen peroxide forecasting model based on long short-term memory and the decision model for catalase dosage pump to derive robust optimal treatments. An empirical study was conducted in a leading semiconductor company to estimate the validity of the proposed framework. The results have shown its practical viability with robust performance under different scenarios for cleaner semiconductor production and sustainability.

Insight into the effect of wastewater-derived dissolved organic matter composition on norgestrel degradation in activated sludge: Coupled bacterial community and molecular characteristics

Dissolved organic matter (DOM) mediates the microbial transformation of micropollutants, including norgestrel (NGT) in natural waters. However, little is known of the effect of complex and variable wastewater-derived DOM composition on NGT degradation during wastewater treatment. In this study, the relationship between the compositions of initial DOM and NGT removal efficiencies of 17 wastewater treatment plants (WWTPs) in spring and summer were analyzed. The different molecular composition of DOM was selected in the lab to further explore its effect on NGT degradation by activated sludge. Results indicated that the DOM composition was a substantial driver of NGT removal in WWTPs. The discrepancies in the initial DOM composition contributed to the differences in the kinetics of NGT degradation by activated sludge. The larger rapid decay phase rates of NGT are usually accompanied by a large proportion of labile substances in DOM. High-throughput sequencing and ultrahigh-resolution mass spectrometry were used to further analyze the evolution of bacterial communities and DOM molecular composition were combined with network analysis to reveal the intrinsic relationship that how DOM composition affected NGT degradation by regulating core microbes. Eighty-nine core OTUs were significantly associated with NGT degradation, and 73 occurred in the rapid decay phase, implying that NGT degradation was mainly regulated by the initial composition of DOM. Nine major transformation products were identified in different groups with widely varying concentrations or relative abundances of these transformation products. This work provides valuable insights into the effects of wastewater-derived DOM composition on NGT degradation by activated sludge and innovatively explores the influence mechanisms from the bacterial community and molecular characterization perspectives.

Spatial fractionation of phosphorus accumulating biofilm: stratification of polyphosphate accumulation and dissimilatory nitrogen metabolism

The spatial distribution of microorganisms represents a critical issue in understanding biofilm function. The aim of the current work was to develop a method for biofilm fractionation, facilitating the analysis of individual spatial biofilm layers using metagenomic approaches. Phosphorus accumulating biofilm applied in an enhanced biological phosphorus removal wastewater treatment plant, were fractionated, and analyzed. The fractionated biofilm revealed a surprising spatial distribution of bacteria and genes, where potential polyphosphate accumulating organisms account for ∼ 47% of the inner layer microbiome. A spatial distribution of genes involved in dissimilatory nitrogen reduction was observed, indicating that different layers of the biofilm were metabolically active during the anoxic and aerobic zones of the phosphorus removal process. The physical biofilm separation into individual fractions unveiled functional layers of the biofilm, which will be important for future understanding of the phosphorus removal wastewater process.

Microbial communities and interactions in full-scale A2/O and MBR wastewater treatment plants

Microorganisms are key to stable system operation and efficient pollutant removal in wastewater treatment plants (WWTPs), whereas the critical information on their seasonal variations is still lacking. Impacts of process types and seasonal variations on microbial communities, metabolisms, and interactions were examined in the anaerobic/anoxic/aerobic (A2/O) and membrane bioreactor (MBR) WWTPs. Environmental factors had a greater impact on pollutant removal than process types. Dissolved oxygen concentration and pH were crucial environmental factors that could simultaneously affect nitrogen metabolism and microbial interactions. Bacteroidetes, Proteobacteria, and Chloroflexi were the dominant phyla. Quorum sensing (QS) systems were detected in these WWTPs, and the N-acyl homoserine lactones QS system was the key pathway responsible for microbial interactions. The obtained microbial information in the full-scale A2/O-WWTP and MBR-WWTP and the potential correlations between microorganisms and environmental factors could provide valuable clues for system optimization.

Evaluating the oxidation inhibition of sulfide in urban sewers using a novel quantitative method

Sulfide inhibition is a critical task for the secure operation of sewer systems, and oxidation is usually utilised to achieve this purpose. However, the effects and mechanism of oxidation during the transformation of sulfur-associated pollutants in gas-liquid-solid phases of sewers have not been extensively evaluated. In this study, a method for quantifying sulfur-associated pollutant exchange pathways in gas-liquid-solid phases of sewers was established. The results showed that although the concentration of sulfide decreased under different oxidation conditions, the consumption of sulfate in sewers clearly increased. The transformation strength of elemental sulfur was high (18.65 mg/L, 35.52% of sulfate from the influent) and the accumulation of sulfate in sediment was obvious (3.49 mg/L, 6.65% of sulfate from the influent). Higher concentrations of sulfate in the influent promoted the generation of sulfide in sediment (8.98 mg/L, 17.10%). Thus, the oxidation process led to the generation of more absolute sulfide. In addition, promoting the metabolism of sulfate-reducing bacteria enhanced the loss of organic carbon in sewers, which might weaken the efficacy of nitrogen and phosphorus removal in wastewater treatment plants. Based on the evaluation of the exchange pathways of sulfur-associated pollutants in sewers, further studies into sulfide inhibition in sewers should consider the above issues to enhance the safe management of urban sewers.

Assessing the exposure to human and veterinary pharmaceuticals in waterbirds: The use of feathers for monitoring antidepressants and nonsteroidal anti-inflammatory drugs

Exposure to active pharmaceutical ingredients (APIs) from both human and veterinary sources is an increasing threat to wildlife welfare and conservation. Notwithstanding, tracking the exposure to pharmaceuticals in non-target and sensitive vertebrates, including birds, is seldom performed and relies almost exclusively on analysing internal organs retrieved from carcasses or from experimentally exposed and sacrificed birds. Clearly, this excludes the possibility of performing large-scale monitoring. Analysing feathers collected from healthy birds may permit this, by detecting APIs in wild birds, including protected and declining species of waterbirds, without affecting their welfare. To this end, we set up a non-destructive method for analysing the presence of non-steroidal anti-inflammatory drugs (NSAIDs), selective serotonin reuptake inhibitors (SSRIs) and noradrenaline reuptake inhibitors (SNRIs) in the feathers of fledglings of both the Mediterranean gull (Ichtyaetus melanocephalus) and the Sandwich tern (Thalasseus sandvicensis). The presence of several NSAIDs and SSRIs above the method quantification limits have confirmed that feathers might be a suitable means of evaluating the exposure of birds to APIs. Moreover, the concentrations indicated that waterbirds are exposed to NSAIDs, such as diclofenac, ibuprofen and naproxen, and SSRIs, such as citalopram, desmethylcitalopram, fluvoxamine and sertraline, possibly due to their widespread use and incomplete removal in wastewater treatment plants (WWTPs). The active ingredient diclofenac raises a the primary concern for the ecosystem and the welfare of the waterbirds, due to its high prevalence (100% and 83.3% in Mediterranean gull and Sandwich tern, respectively), its concentrations detected in feathers (11.9 ng g−1 and 6.7 ng g−1 in Mediterranean gull and Sandwich tern, respectively), and its documented toxicity toward certain birds.

Systematic calibration of N2O emissions from a full-scale WWTP including a tracer test and a global sensitivity approach

Nitrous oxide (N2O) is a greenhouse gas (GHG) emitted during biological nitrogen removal from wastewater treatment plants (WWTPs). Some modelling tools have been proposed to predict N2O emissions during the design and operation of WWTPs. In this study, the novel ASM2d-N2O model, which accounts for the production of N2O in nutrient removal WWTPs, was used to study the associated emissions from a full-scale WWTP with two independent lines. Firstly, the hydraulics of the WWTP was characterized by a residence time distribution test, showing the flow was equally divided into the two treatment lines (49.3 vs. 50.7%), that each reactor worked as an ideal continuous stirred tank reactor and the secondary settler model flux was similar to a plug-flow reactor. The ASM2d-N2O model was then calibrated using experimental data obtained under dynamic conditions. A global sensitivity analysis was used to select, among 59 model parameters, five candidates that resulted to be related to nitrifying organisms. Different parameter subsets up to four parameters were evaluated, being the subset [µNOB, qAOB_AMO, KO2_NOB, KNO2_NOB] the best, achieving 53.3% reduction of the calibration cost function. The model fit obtained provided a reasonably description of nutrients and N2O emission trends, considering the inherent operational variability suffered in full-scale WWTPs. Finally, a simulation-based study showed that, for the given WWTP and operational conditions, an unbalanced distribution of flow-rate between the two treatment lines did not result in a significant increase on N2O emissions. The results obtained show that this model can be a suitable tool for predicting N2O emissions in full-scale WWTPs, and can therefore be used to find operational conditions that help to minimise these emissions.

Insight into the role of different extracellular polymeric substances components on trimethoprim adsorption by activated sludge

Adsorption is the primary mechanism of antibiotic removal in wastewater treatment plants, wherein the extracellular polymeric substances (EPS) of the activated sludge play an important role. Due to their complex characteristics, the effect of EPS components on antibiotic adsorption is unknown. Therefore, in this study, the role of main components of EPS in antibiotic adsorption was explored using enzymatic treatment. The results revealed that proteinase K and α-amylase can efficiently hydrolyse the proteins and polysaccharides of EPS. The protein content of EPS reduced from 31.25 mg/g VSS to 21.53, 18.75, and 10.76 mg/g VSS, after treatment with proteinase K, α-amylase and their combination, respectively; the polysaccharides content also observed a similar decrease from 15.20 mg/g VSS to 8.22, 7.83, and 6.03 mg/g VSS, respectively. The humic substance in EPS was stable during enzymatic treatment. The equilibrium adsorption capacity of activated sludge treated by enzyme for trimethoprim (TMP)- a typical antibiotic, was significantly increased from 2.19 μg/g VSS to 4.68, 5.34, and 8.36 μg/g VSS after treatment with proteinase K, α-amylase and their mixture. The adsorption process was adequately described by pseudo-second-order kinetic model. A multivariable linear regression model was subsequently used to quantify the adsorption capacity of activated sludge for TMP considering the concentration of EPS components. The modelling and validated results showed that the model could satisfactorily predict the TMP adsorption capacity. The results of this study can provide new insights into the role of EPS on antibiotic transformation in biological wastewater treatment systems.

Effect of tetracycline on nitrogen removal in Moving Bed Biofilm Reactor (MBBR) System.

The effect of tetracycline (TC) on nitrogen removal in wastewater treatment plants has become a new problem. This study investigated the effects of TC on nitrogen removal using a Moving Bed Biofilm Reactor system. The results showed that there was no significant effect on nitrogen removal performance when the concentration of TC was 5 mg/L, and that the total nitrogen (TN) removal efficiency could reach 75–77%. However, when the concentration of TC increased to 10 mg/L, the denitrification performance was affected and the TN removal efficiency decreased to 58%. The abundance of denitrifying bacteria such as those in the genus Thauera decreased, and TC-resistant bacteria gradually became dominant. At a TC concentration of 10 mg/L, there were also increases and decreases, respectively, in the abundance of resistance and denitrification functional genes. The inhibitory effect of TC on denitrification was achieved mainly by the inhibition of nitrite-reducing bacteria.

Monitoring the performance of wastewater treatment plants for organic matter removal using excitation-emission matrix fluorescence

This study has assessed the usefulness of excitation-emission matrix fluorescence (EEMF) as a fast and simple analytical technique to track changes in dissolved organic matter (DOM) during the sequence of treatment in wastewater treatment plants (WWTPs). Three different industrial wastewaters and treatment plants have been studied in this work: an industrial park wastewater treated in an independent line at the Burgos WWTP (Spain), a food industry wastewater (crisps and snacks manufacturing) that was treated in a MBR (Membrane Biological Reactor) pilot plant (University of Burgos) and a municipal landfill leachate treated in a physicochemical treatment plant within the same landfill.Removal percentages for the wastewater organic matter at each stage of the treatment plants were successfully obtained by monitoring the main fluorescence peaks: protein-like peaks (tryptophan-like peaks T1, T2 and tyrosine-like peaks B1, B2), humic-like peaks (fulvic-like peak A and humic-like peak C) and microbially-derived peak M. Therefore, EEMF readily allows the assessment of the reactivity of the different types of organic matter towards specific treatments, such as clarification, biodegradation, filtration, etc. Among the wastewaters studied, the food industry wastewater exhibited the greater diversity of fluorescence peaks (B1, B2, T1, T2, A1, A2 and M) whereas the landfill leachate only showed the presence of humic substances (mainly humic-like peak C). This study has demonstrated that EEMF is a useful and user-friendly technique to monitor the performance of wastewater treatment plants for organic matter removal, allowing a rapid response to potential problems in the treatment.

Occurrence and removal of progestogens from wastewater treatment plants in China: Spatiotemporal variation and process comparison

This study investigated the overall occurrence and spatiotemporal variation of 19 progestogens in 608 samples collected from 17 wastewater treatment plants (WWTPs) distributed across China during four seasons. The aqueous removal efficiencies of progestogens were calculated and the efficacies of process segments, secondary and advanced processes, and process units in the removal of progestogens were explored. The results indicated that progestogens were widely detected in investigating WWTPs, with the progesterone, dydrogesterone, dienogest, ethisterone, and norethindrone were always dominant in the influent, secondary effluent, final effluent, and excess sludge. Seasonally, the influent exhibited more variability than the other matrices, that 10 progestogens concentrations varied significantly during the four seasons. Spatially, the influent concentrations of progestogens were generally higher in northern WWTPs than that in southern WWTPs during spring and summer. Eight progestogens were stably removed by the WWTPs across seasons, and most progestogens varied considerably in removal in different WWTPs. The conventional process segment was the dominant contributor to progestogen removal. The anaerobic-anoxic-oxic process and a combined process consisting of densadeg and cloth media filter and ultraviolet disinfection showed the highest removal of progestogens among various secondary and advanced treatment processes, respectively. Mass balance analysis showed that most progestogens were effectively eliminated in the aerobic unit, with biodegradation being the primary removal pathway. This study presents the first picture of the spatiotemporal dynamics of the distribution of progestogens in WWTPs of China and provides valuable information for better understanding of the occurrence and removal of progestogens in WWTPs.

Model-based analysis of the effect of temperature in biological wastewater treatment plants for simultaneous removal of organic matter, nitrogen, and phosphorous

The effect of temperature on the phosphorous, nitrogen, and organic matter removal in an activated sludge system(ASS) has been assessed in this research. Benchmark Simulation Model No.1 (BSM1-P) with an ASS (ASM3bioP) is used and the temperature is chosen between 10 to 35°C. The kinetic expressions for the maximum growth rate of heterotrophic biomass, autotrophic, and phosphate accumulating organisms and their decay rates are considered. Total ammonia, nitrogen, and phosphorous in the effluent are analysed and when the range of temperature is less than 15°C and greater than 30°C, the effluent quality deviates from the legal requirements.