Concentrations Of Micropollutants Research Articles

Intra-event variations of organic micropollutants in highway runoff and a presedimentation-biofilter treatment facility

The study assessed the quality of highway runoff and a stormwater treatment system, focusing on intra-event variations (IEVs: variations within a runoff/effluent event) of the concentration of organic micropollutants (OMPs) including bisphenol-A, alkylphenols, polycyclic aromatic hydrocarbons (PAHs), and petroleum hydrocarbons (PHCs). IEVs of OMPs varied considerably with no particular recurring pattern in highway runoff and presedimentation effluent, displaying sporadic strong first flushes. IEVs are significantly associated with rainfall intensity variations, especially for particle-bound substances such as PAHs and PHCs. However, phenolic substances showed distinct IEV patterns compared to total suspended solids, PAHs, and PHCs, likely due to their higher solubility and mobility. Downstream sand filter (SF) and vegetated biofilter (BFC) mitigated IEVs, leading to more uniform discharge during outflow events. Although BFC’s IEVs were indiscernible due to low effluent concentrations, SF’s IEVs often peaked at the beginning of events (within the first 100 of ⁓600 m3), exceeding the lowest predicted non-effect concentrations for five PAHs, bisphenol-A, and octylphenol. This study highlights the advantage of IEV analysis over conventional event mean concentration analysis for identifying critical effluent stages, crucial for developing control strategies to protect sensitive water recipients or for reuse applications.

Exploring long-term retention and reactivation of micropollutant biodegradation capacity.

The factors limiting micropollutant biodegradation in the environment and how to stimulate this process have often been investigated. However, little information is available on the capacity of microbial communities to retain micropollutant biodegradation capacity in the absence of micropollutants or to reactivate micropollutant biodegradation in systems with fluctuating micropollutant concentrations. This study investigated how a period of 2months without the addition of micropollutants and other organic carbon affected micropollutant biodegradation by a micropollutant-degrading microbial community. Stimulation of micropollutant biodegradation was performed by adding different types of dissolved organic carbon (DOC)-extracted from natural sources and acetate-increasing 10 × the micropollutant concentration, and inoculating with activated sludge. The results show that the capacity to biodegrade 3 micropollutants was permanently lost. However, the biodegradation activity of 2,4-D, antipyrine, chloridazon, and its metabolites restarted when these micropollutants were re-added to the community. Threshold concentrations similar to those obtained before the period of no substrate addition were achieved, but biodegradation rates were lower for some compounds. Through the addition of high acetate concentrations (108mg-C/L), gabapentin biodegradation activity was regained, but 2,4-D biodegradation capacity was lost. An increase of bentazon concentration from 50 to 500µg/L was necessary for biodegradation to be reactivated. These results provide initial insights into the longevity of micropollutant biodegradation capacity in the absence of the substance and strategies for reactivating micropollutant biodegrading communities.

Exploring long-term retention and reactivation of micropollutant biodegradation capacity.

The factors limiting micropollutant biodegradation in the environment and how to stimulate this process have often been investigated. However, little information is available on the capacity of microbial communities to retain micropollutant biodegradation capacity in the absence of micropollutants or to reactivate micropollutant biodegradation in systems with fluctuating micropollutant concentrations. This study investigated how a period of 2months without the addition of micropollutants and other organic carbon affected micropollutant biodegradation by a micropollutant-degrading microbial community. Stimulation of micropollutant biodegradation was performed by adding different types of dissolved organic carbon (DOC)-extracted from natural sources and acetate-increasing 10 × the micropollutant concentration, and inoculating with activated sludge. The results show that the capacity to biodegrade 3 micropollutants was permanently lost. However, the biodegradation activity of 2,4-D, antipyrine, chloridazon, and its metabolites restarted when these micropollutants were re-added to the community. Threshold concentrations similar to those obtained before the period of no substrate addition were achieved, but biodegradation rates were lower for some compounds. Through the addition of high acetate concentrations (108mg-C/L), gabapentin biodegradation activity was regained, but 2,4-D biodegradation capacity was lost. An increase of bentazon concentration from 50 to 500µg/L was necessary for biodegradation to be reactivated. These results provide initial insights into the longevity of micropollutant biodegradation capacity in the absence of the substance and strategies for reactivating micropollutant biodegrading communities.

Total RNA analysis of the active microbiome on moving bed biofilm reactor carriers under incrementally increasing micropollutant concentrations.

Micropollutants are increasingly prevalent in the aquatic environment. A major part of these originates from wastewater treatment plants since traditional treatment technologies do not remove micropollutants sufficiently. Moving bed biofilm reactors (MBBRs), however, have been shown to aid in micropollutant removal when applied to conventional wastewater treatment as a polishing step. Here, we used Total RNA sequencing to investigate both the active microbial community and functional dynamics of MBBR biofilms when these were exposed to increasing micropollutant concentrations over time. Concurrently, we conducted batch culture experiments using biofilm carriers from the MBBRs to assess micropollutant degradation potential. Our study showed that biofilm eukaryotes, in particular protozoa, were negatively influenced by micropollutant exposure, in contrast to prokaryotes that increased in relative abundance. Further, we found several functional genes that were differentially expressed between the MBBR with added micropollutants and the control. These include genes involved in aromatic and xenobiotic compound degradation. Moreover, the biofilm carrier batch experiment showed vastly different alterations in benzotriazole and diclofenac degradation following the increased micropollutant concentrations in the MBBR. Ultimately, this study provides essential insights into the microbial community and functional dynamics of MBBRs and how an increased load of micropollutants influences these dynamics.

Temperature-driven and discharge-driven variability of organic micropollutants in a large urban river and its implications for risk-based monitoring

Urban rivers are exposed to an increasing load of organic micropollutants from wastewater effluent posing an ecological as well as public health hazard. One-off surveys can capture a snapshot of the pollution profile but fail to reveal the full scale of spatial and temporal heterogeneity. In the present study, 41 micropollutants (non-steroid anti-inflammatory drugs (NSAID), antihypertensives, antiepileptic, antidiabetic, antibiotics, iodinated contrast media (ICM), corrosion inhibitors, pesticides) were monitored every two weeks for one-year upstream and downstream of the Budapest metropolitan area in Danube River (336 samples total). ICMs, benzotriazoles and metamizole degradation products were detected in highest concentration regularly exceeding 100 ng/L. Median concentration of other pharmaceuticals ranged from <1 to 26 ng/L, while pesticides were typically below 10 ng/L. Variability of micropollutant concentration was primarily temporal, exhibiting two different patterns: (1) inverse correlation to river discharge, observed for corrosion inhibitors and carbamazepine (r = −0.505 to −0.665) or (2) inverse correlation to water temperature, observed primarily for ICMs, antihypertensives and antibiotics, r = −0.654 to −0.904). Temperature dependence was also significant after correcting for river discharge. Relative increase of pharmaceuticals was 2–134% after the metropolitan area, partially explained by emission estimates calculated from retail data and metabolization rates.The concentration of five ICMs (iopamidol in 100, iodixanol in 96, diatrizoate in 22, iomeprol in 21 and iohexol 13% of the samples) and two NSAIDs (ibuprofen and diclofenac (in 31.5 and 23% of the samples) exceeded the predicted no environmental effect concentration, posing a risk to algae (HQ = 1.2–6) and fish (HQ = 1.4–1.9), respectively. Results suggest that risk-based monitoring and risk management efforts should focus on ICMs, NSAIDs and industrial chemicals, taking into account that sampling in cold periods and during low flow provides the worst-case estimates.

Tolerance to environmental pollution in the freshwater crustacean Asellus aquaticus: A role for the microbiome.

Freshwater habitats are frequently contaminated by diverse chemicals of anthropogenic origin, collectively referred to as micropollutants, that can have detrimental effects on aquatic life. The animals' tolerance to micropollutants may be mediated by their microbiome. If polluted aquatic environments select for contaminant-degrading microbes, the acquisition of such microbes by the host may increase its tolerance to pollution. Here we tested for the potential effects of the host microbiome on the growth and survival of juvenile Asellus aquaticus, a widespread freshwater crustacean. Using faecal microbiome transplants, we provided newly hatched juveniles with the microbiome isolated from donor adults reared in either clean or micropollutant-contaminated water and, after transplantation, recipient juveniles were reared in water with and without micropollutants. The experiment revealed a significant negative effect of the micropollutants on the survival of juvenile isopods regardless of the received faecal microbiome. The micropollutants had altered the composition of the bacterial component of the donors' microbiome, which in turn influenced the microbiome of juvenile recipients. Hence, we show that relatively high environmental concentrations of micropollutants reduce survival and alter the microbiome composition of juvenile A. aquaticus, but we have no evidence that tolerance to micropollutants is modulated by their microbiome.

Quartz Crystal Microbalance as a Holistic Detector for Quantifying Complex Organic Matrices during Liquid Chromatography: 2. Compound-Specific Isotope Analysis.

In carbon-compound-specific isotope analysis (carbon CSIA) of environmental micropollutants, purification of samples is often required to guarantee accurate measurements of a target compound. A companion paper has brought forward an innovative approach to couple a quartz crystal microbalance (QCM) with high-performance liquid chromatography (HPLC) for the online quantification of matrices during a gradient HPLC purification. This work investigates the benefit for isotope analysis of polar micropollutants typically present in environmental samples. Here, we studied the impact of the natural organic matter (NOM) on the isotopic integrity of model analytes and the suitability of the NOM-to-analyte ratio as a proxy for the sample purity. We further investigated limitations and enhancement of HPLC purification using QCM on C18 and C8 phases for single and multiple targets. Strong isotopic shifts of up to 3.3% toward the isotopic signature of NOM were observed for samples with an NOM-to-analyte ratio ≥10. Thanks to QCM, optimization of matrix removal of up to 99.8% of NOM was possible for late-eluting compounds. The efficiency of HPLC purification deteriorated when aiming for simultaneous purification of two or three compounds, leading to up to 2.5% less NOM removal. Our results suggest that one optimized HPLC purification can be achieved through systematic screening of 3 to 5 different gradients, thereby leading to a shift of the boundaries of accurate carbon CSIA by up to 2 orders of magnitude toward lower micropollutant concentrations.

Plant-Wide Models for Optimizing the Operation and Maintenance of BTEX-Contaminated Wastewater Treatment and Reuse

Benzene, toluene, ethylbenzene and xylenes, collectively known as BTEX compounds, are significant emerging contaminants in municipal wastewater. Stricter effluent quality regulations necessitate their removal, especially with concerns about organic micropollutant concentrations. Water scarcity further underscores the need for wastewater treatment to ensure safe agricultural or drinking water supplies. Although biological treatment partially reduces BTEX levels through processes like biodegradation and sorption, additional purification using physico-chemical methods is crucial for substantial reduction. This paper aims to outline plant-wide simulation methods for treating BTEX-contaminated sewage and facilitating reuse, adhering to IWA Good Modelling Practice Guidelines. The model, built upon the MiniSumo process model, incorporates equations detailing BTEX metabolism and removal kinetics, informed by an extensive literature review. Using a variant of the Benchmark Simulation Model with granular activated carbon for water reuse, the study examines strategies for improving effluent quality and minimizing operational costs. These strategies include adjusting the sludge retention time and airflow to enhance BTEX degradation and stripping, respectively, and comparing maintenance approaches for the GAC tower.

Occurrence of micropollutants in rural domestic wastewater in Zhejiang Province, China and corresponding wastewater-based epidemiology analysis

By 2021, rural regions in China were occupied by over 500 million residents, generating an annual volume of 19.5 billion m3 of rural domestic wastewater (RDW). This study aimed to investigate the occurrence and removal of micropollutants (MPs) in RDW treatment facilities and to perform a corresponding wastewater-based epidemiology analysis (WBE). Our findings indicated the significantly high levels of influent MPs, particularly pharmaceuticals, such as ofloxacin and diclofenac being most prevalent (ranging from several to tens of μg/L) across different facilities. After various treatments, regular water indexes in the effluent, like NH3 -N and COD, have basically satisfied the local discharge standard. However, the concentration of certain dominant MPs in effluent remained notably high, ranging from hundreds of ng/L to several μg/L. The risk quotients of MPs like diclofenac, ciprofloxacin, ofloxacin, sulfamethoxazole, diuron, and isoproturon were all above 1 in the effluent, signifying significant hazards to aquatic organisms. The quantitative meta-analysis revealed higher average standardized removal efficiency for membrane bioreactor (MBR) treatment (-11 %) compared to anaerobic/anoxic/aerobic (A2O) treatment (11 %), indicating the higher efficiency of MBR treatment in outperforming the A2O as a secondary treatment. Additionally, employing biofilter as a tertiary treatment proved to be more effective as compared to flocculation-air flotation and artificial wetlands. Moreover, the results of WBE analysis showed that diclofenac and ofloxacin emerged as the most commonly used pharmaceuticals (of seven), with consumption levels recorded at 1222 and 517 mg/(d·103 capita), with daily defined doses per day per 103 capita of 12.2/1000 and 1.29/1000, respectively. This study addresses the existing knowledge gaps regarding the occurrence and removal of MPs in RDW and offers valuable insights into pharmaceutical consumption patterns in rural regions, thereby improving our understanding of public health.

Investigation of organic micropollutant pollution in İzmit Bay: a comparative study of passive sampling and instantaneous sampling techniques.

In this study, we used a comprehensive array of sampling techniques to examine the pollution caused by organic micropollutants in İzmit Bay for the first time. Our methodology contains spot seawater sampling, semi-permeable membrane devices (SPMDs) passive samplers for time-weighted average (TWA), and sediment sampling for long-term pollution detection in İzmit Bay, together. Additionally, the analysis results obtained with these three sampling methods were compared in this study. Over the course of two seasons in 2020 and 2021, we deployed SPMDs for 21days in the first season and for 30days in the second season. This innovative approach allowed us to gather sea water samples and analyze them for the presence of polycyclic aromatic hydrocarbons (Σ15 PAHs), polychlorinated biphenyls (Σ7 PCBs), and organochlorine pesticides (Σ11 OCPs). Using SPMD-based passive sampling, we measured micropollutant concentrations: PAHs ranged from 1963 to 10342pg/L in 2020 and 1338 to 6373pg/L in 2021; PCBs from 17.46 to 61.90pg/L in 2020 and 8.37 to 78.10pg/L in 2021; and OCPs from 269.2 to 8868pg/L in 2020 and 141.7 to 1662pg/L in 2021. Our findings revealed parallels between the concentrations of PAHs, PCBs, and OCPs in both SPMDs and sediment samples, providing insights into the distribution patterns of these pollutants in the marine ecosystem. However, it is worth noting that due to limited data acquisition, the suitability of spot sampling in comparison to instantaneous sampling remains inconclusive, highlighting the need for further investigation and data collection.

Natural magnetite as an effective and long-lasting catalyst for CWPO of azole pesticides in a continuous up-flow fixed-bed reactor

The global occurrence of micropollutants in water bodies has raised concerns about potential negative effects on aquatic ecosystems and human health. EU regulations to mitigate such widespread pollution have already been implemented and are expected to become increasingly stringent in the next few years. Catalytic wet peroxide oxidation (CWPO) has proved to be a promising alternative for micropollutant removal from water, but most studies were performed in batch mode, often involving complex, expensive, and hardly recoverable catalysts, that are prone to deactivation. This work aims to demonstrate the feasibility of a fixed-bed reactor (FBR) packed with natural magnetite powder for the removal of a representative mixture of azole pesticides, recently listed in the EU Watch Lists. The performance of the system was evaluated by analyzing the impact of H2O2 dose (3.6–13.4 mg L−1), magnetite load (2–8 g), inlet flow rate (0.25–1 mL min−1), and initial micropollutant concentration (100–1000 µg L−1) over 300 h of continuous operation. Azole pesticide conversion values above 80% were achieved under selected operating conditions (WFe3O4 = 8 g, [H2O2]0 = 6.7 mg L−1, flow rate = 0.5 mL min−1, pH0 = 5, T = 25 °C). Notably, the catalytic system showed a high stability upon 500 h in operation, with limited iron leaching (< 0.1 mg L−1). As a proof of concept, the feasibility of the system was confirmed using a real wastewater treatment plant (WWTP) effluent spiked with the mixture of azole pesticides. These results represent a clear advance for the application of CWPO as a tertiary treatment in WWTPs and open the door for the scale-up of FBR packed with natural magnetite.

Implications of the transition towards water-wise approaches in urban areas: Elucidating the risk from micropollutants release

The transition towards circular and sustainable urban water systems, embracing a water-wise city approach, results in highly interconnected systems, introducing complexities in managing water quality due to the intricate interplay of pollutant sources, pathways, and receptors in urban environments. This study focuses on assessing the impact of transitioning to a water-wise city approach on water quality. The analysis employs an integrated model-based approach to evaluate the release of micropollutants (PFOA, PFOS, pyrene) in the urban water system, considering potential future changes. We considered Milan (Italy) as a case study and explored sustainable urban water management strategies related to the hydraulic reconnection of canals, including (i) the use of groundwater for energy purposes, (ii) the establishment of a separate stormwater sewer system, and (iii) the indirect reuse of reclaimed water for crop irrigation. Acute and chronic environmental risks were assessed at various locations of the recipients, under different water management and climate change scenarios. Uncertainties on projections related to rainfall and runoff concentrations were also considered. The model accurately predicted average micropollutants concentrations in the current situation. PFOA and PFOS exhibit chronic, but not acute risks in all scenarios; high removal efficiency is required to reduce the risk at acceptable levels. Pyrene poses higher risks for increasing separation fractions of the sewer system, with further increase for climate change, but concentration uncertainty has more influence than precipitation uncertainty on the risk extent. This study provides a water management framework, identifying critical sources and locations under current, future, and climate change scenarios.

Assessment and modeling of benzene micropollutant in surface waters proximal to coal-fired thermal power plants

ABSTRACT Micropollutants of priority have gained significant attention due to their rising concentrations and persistence in aquatic environments. Among these significant micro-pollutants is benzene, released into the environment because of mining activities, thermal power plants, and certain industrial operations, thereby contributing to environmental contamination. This study monitored benzene concentrations in the Orhaneli River over a year, employing an artificial neural network (ANN) approach to formulate a predictive model for benzene micropollutant concentrations. To provide input to the ANN, Principal Component Analysis (PCA) was employed, utilizing parameters such as precipitation, temperature, humidity, pH, flow rate, dissolved oxygen, conductivity, total organic carbon, and total nitrogen. Eleven backpropagation algorithms were compared, with the Levenberg-Marquardt algorithm identified as the optimal training algorithm. For the selected training algorithm, an optimized number of 6 neurons in the hidden layer provided the best predictions for benzene concentrations. The three-layered optimized ANN model achieved an impressive correlation coefficient (R2) of 0.9889.

A harmonized Danube basin-wide multi-compartment concentration database to support inventories of micropollutant emissions to surface waters

BackgroundThe European Water Framework Directive foresees the establishment of emission inventories for micropollutants (MP) to facilitate an evidence-based development of mitigation measures. Regionalized pathway analysis constitutes a moderately data-intensive approach to quantify the contribution of different pathways to the total pollution of surface waters. So far, only few European member states have created an inventory that includes diffuse pathways. The fundamental basis to enable it is an accessible, well-structured and harmonized database with data on the concentration of MPs in multiple compartments, such as soils, groundwater, atmospheric deposition and urban systems. Combined with the water and suspended substance balance in river basins, such data enables the estimation of emission loads via specific pathways. In the Danube River Basin, but in general in Europe, a public data management platform with such scope and criteria is still lacking.ResultsWe collected and harmonized MP measurements across multiple compartments and countries together with key metadata, harmonized and combined them into a new database. The resulting tool, available for download, facilitates the assessment of current data availability, in terms of quantity and quality. For example, while the majority of available data stems from groundwater and surface water, other highly relevant compartments are scarcely represented. By examining differences in MP concentration level across compartments, the database can lead to understand the relevance of specific emission pathways and thus to prioritize data-retrieval and calculation efforts in modelling applications. Selected examples show how to exploit the metadata associated to the measurements to extrapolate the results to regions not covered by specific monitoring programmes. For example, PFAS concentrations in treated wastewater show significant dependence on the design capacity of the treatment plant.ConclusionsThis study showcases how such database can support the setup of emission inventories, guide data providers and national authorities in prioritizing the allocation of resources for new surveys and in optimizing their national data collection and management systems. The process tested showed a great need for enhanced data literacy across countries and institutions to increase data availability and quality to secure the exploitation of the full information potential generated via monitoring programmes.

Impact of Doxycycline Addition on Activated Sludge Microflora and Microbial Communities

Municipal wastewater treatment plants (WWTPs) are exposed to high concentrations of micropollutants that can impact conventional activated sludge treatment. The consequences of this include failure to meet discharge standards and the disintegration of flocs, leading to poor sludge settleability. This lab-scale study focuses on the influence of doxycycline, an antibiotic widely used against human and animal diseases, on protozoa, metazoa, and bacterial communities under sludge growing conditions. Doxycycline was added to the mixed liquor of a communal WWTP up to 0, 100, 200, and 400 mg of doxycycline L−1 and incubated in batch conditions for 23 days. The regular addition of nutrient and carbon sources was preformed every 2 days to prevent sludge starvation. Sludge growth, conductivity, and settleability were measured and compared to sludge microbial community structure, determined by microscopic observations and high-throughput 16S rDNA sequencing. The high doxycycline concentration negatively impacted settleability and correlated with a decrease in bacterial diversity and floc disintegration. The addition of doxycycline promoted the enrichment of Proteobacteria Brevundimonas sp., Luteibacter anthropi, and the Bacteroidetes Chryseobacterium massoliae. These species are known to be resistant to a wide spectrum of antibiotics, including tetracyclines. A study of a larger scale may be conducted based on this study’ results.

Water Framework Directive micropollutant monitoring mirrors catchment land use: Importance of agricultural and urban sources revealed

River monitoring programs worldwide consistently unveil micropollutant concentrations (pesticide, pharmaceuticals, and industrial chemicals) exceeding regulatory quality targets with deteriorating effects on aquatic communities. However, both the composition and individual concentrations of micropollutants are likely to vary with the catchment land use, in particular regarding urban and agricultural area as the primary sources of micropollutants. In this study, we used a dataset of 109 governmental monitoring sites with micropollutants monitored across the Federal State of North Rhine-Westphalia, Germany, to investigate the relationship between high-resolution catchment land use (distinguishing urban, forested and grassland area as well as 22 different agricultural crop types) and 39 micropollutants using Linear Mixed Models (LMMs). Ecotoxicological risks were indicated for mixtures of pharmaceutical and industrial chemicals for 100 % and for pesticides for 55 % of the sites. The proportion of urban area in the catchment was positively related with concentrations of most pharmaceuticals and industrial chemicals (R2 up to 0.54), whereas the proportions of grassland and forested areas generally showed negative relations. Cropland overall showed weak positive relationships with micropollutant concentrations (R2 up to 0.29). Individual crop types, particularly vegetables and permanent crops, showed higher relations (R2 up to 0.46). The findings suggest that crop type-specific pesticide applications are mirrored in the detected micropollutant concentrations. This highlights the need for high-resolution spatial land use to investigate the magnitude and dynamics of micropollutant exposure and relevant pollution sources, which would remain undetected with highly aggregated land use classifications. Moreover, the findings imply the need for tailored management measures to reduce micropollutant concentrations from different sources and their related ecological effects. Urban point sources, could be managed by advanced wastewater treatment. The reduction of diffuse pollution from agricultural land uses requires additional measures, to prevent pesticides from entering the environment and exceeding regulatory quality targets.

Reviewing the interdecadal dynamics of micropollutants in the Tanzanian coastal zone from 2002 to 2022.

The Tanzanian coast is a vastly diversified ecosystem offering ecological, cultural, and economic services. However, anthropogenic and environmental stressors threaten its productivity and sustainability, prompting extensive research to understand the contamination extent, sources, and impacts. This review covers 77 original field research studies published between 2002 and 2022, focusing on the Tanzanian coastal area. A summary of information on the occurrences, levels, distributions, sources, and impacts of organic and inorganic micropollutants in environmental and biological compartments is provided. The studies were further discussed based on their research focus, where seven key areas were identified, which included the types of micropollutants analyzed, the parameters sampled, the locations investigated, and the crucial conclusions reached. The aim was to evaluate the research trends and identify gaps for future investigations. The studies reveal varying contamination levels, from low to severe, encompassing metals, persistent organic pollutants, pesticide residues, nutrients, and microbial contaminants. However, data gaps exist for micropollutant concentrations in ambient air, microplastics, pharmaceuticals, and emerging contaminants of concern. With increasing urbanization and socio-economic activities, the review emphasizes the necessity for solution-based research to remove and control micropollutants in the area. Addressing these challenges is crucial for sustaining the diverse ecological nature of this vital coastal system.

Micropollutants in biochar produced from sewage sludge: A systematic review on the impact of pyrolysis operating conditions

Biochar obtained from sewage sludge serves as a valuable soil amendment in agriculture, enhancing soil properties by increasing the nutrient content, cation exchange capacity, water retention, and oxygen transmission. However, its utilisation is hampered by the presence of micropollutants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and volatile organic compounds (VOCs). Previous studies indicate that the type and amount of micropollutants can be significantly adjusted by selecting the right process parameters. This literature review provides an overview of how (1) pyrolysis temperature, (2) carrier gas flow and type, (3) heating rate, and (4) residence time affect the concentration of micropollutants in biochar produced from sewage sludge. The micropollutants targeted are those listed by the European Biochar Certificate (EBC) and by the International Biochar Institution (IBI), including PAHs, PCDD/Fs, PCBs and VOCs. In addition, per- and poly-fluoroalkyl substances (PFAS) are also considered due to their presence in sewage sludge.The findings suggest that higher pyrolysis temperatures reduce micropollutant levels. Moreover, the injection of a carrier gas (N2 or CO2) during the pyrolysis and cooling processes effectively lowers PAHs and PCDD/Fs, by reducing the contact of biochar with oxygen, which is crucial in mitigating micropollutants. Nevertheless, limited available data impedes an assessment of the impact of these parameters on PFAS in biochar. In addition, further research is essential to understand the effects of carrier gas type, heating rate, and residence time in order to determine the optimal pyrolysis process parameters for generating clean biochar.

Impact of anaerobic zone on biodegradation of micropollutants: Comparison of micropollutants’ removal efficiencies in lab-scale anaerobic bioreactor and in full-scale anaerobic zone

To predict the fate of micropollutants (MPs) in the anaerobic zone at the lab and full-scale levels, anaerobically biological removal (adsorption and biodegradation) of 40 MPs was performed. Among the 40 MPs in the full-scale anaerobic tank, estriol and acetaminophen showed the highest total removal efficiencies in the anaerobic zone (∼100 %). In batch tests, five MPs belonging to estrogens (estriol and 17b-estradiol), parabens (ethyl paraben and propyl paraben), and iopromide were completely removed within 12 h. Meanwhile, MPs belonging to perfluorinated compounds and nitrosamines were infrequently removed (<20 %) within 12 h. The obtained solid-water distribution coefficient (Kd) and biodegradation rate constants (Kbiol) values were used for predictive modeling of residual MPs’ concentrations in the full-scale anaerobic zone and were compared with Kbiol obtained from the oxic zone. Most MPs had similar Kbiol values regardless of redox conditions (oxic or anaerobic); however, caffeine, ibuprofen, naproxen, trimethoprim, and iopromide showed different values depending on the redox conditions. Differences in the efficiencies of total MP’ removal were noted between that predicted via modeling and actually observed (-37 % [iopromide] to 49 % [caffeine]) under altered conditions such as levels of dissolved oxygen (DO) and introduction of the primary or returned sludge. This implies that strictly anaerobic conditions are required for the degradation of specific MPs. The Kd and Kbiol values obtained in this study could help predict changes in the concentration of MPs in the anaerobic zone.

New insights into vermiremediation of sewage sludge: The effect of earthworms on micropollutants and vice versa

Vermicomposting represents an environmentally friendly method for the treatment of various types of biowastes, including sewage sludge (SS), as documented in numerous studies. However, there are few papers providing insights into the mechanisms and toxicity effects involved in SS vermicomposting to present a comprehensive overview of the process. In this work, the vermiremediation of SS containing various micropollutants, including pharmaceuticals, personal care products, endocrine disruptors, and per/polyfluoroalkyl substances, was studied. Two SSs originating from different wastewater treatment plants (WWTP1 and WWTP2) were mixed with a bulking agent, moistened straw, at ratios of 0, 25, 50, and 75% SS. Eisenia andrei earthworms were introduced into the mixtures, and after six weeks, the resulting materials were subjected to various types of chemical and toxicological analyses, including conventional assays (mortality, weight) as well as tissue- and cell-level assays, such as malondialdehyde production, cytotoxicity tests and gene expression assays. Through the vermiremediation process significant removal of diclofenac (90%), metoprolol (88%), telmisartan (62%), and triclosan (81%) was achieved. Although the concentrations of micropollutants were substantially different in the original SS samples, the micropollutants vermiaccumulated to a similar extent over the incubation period. The earthworms substantially eliminated the present bacterial populations, especially in the 75% SS treatments, in which the average declines were 90 and 79% for WWTP1 and WWTP2, respectively. To the best of our knowledge, this is the first study to investigate the vermiremediation of such a large group of micropollutants in real SS samples and provide a thorough evaluation of the effect of SS on earthworms at tissue and cellular level.