Niabella defluvii sp. nov., isolated from influent water of a wastewater treatment plant.

Strain I65T (=KACC 22647T=JCM 35315T), a novel Gram-stain-negative, strictly aerobic, non-motile, non-spore-forming, rod-shaped, and orange-pigmented bacterium was isolated from influent water of a wastewater treatment system after treatment with several antibiotics, such as meropenem, gentamicin, and macrolide. The newly identified bacterial strain I65T exhibits significant multi-drug and heavy metal resistance characteristics. Strain I65T was grown in Reasoner's 2A medium [0 %-2 % (w/v) NaCl (optimum, 0 %), pH 5.0-10.0 (optimum, pH 7.0), and 20-45°C (optimum, 30 °C)]. Phylogenetic analysis based on 16S rRNA gene sequencing confirmed that strain I65T was closely related to Niabella yanshanensis CCBAU 05354T (99.56 % sequence similarity), Niabella hibiscisoli THG-DN5.5T (97.51 %), and Niabella ginsengisoli GR10-1T (97.09 %). Further analysis of the whole-genome sequence confirmed that the digital DNA-DNA hybridization, average nucleotide identity, and average amino acid identity values between strain I65T and N. yanshanensis CCBAU 05354T were 23.4, 80.7, and 85.0 %, respectively, suggesting that strain I65T is distinct from N. yanshanensis. The genome size of strain I65T was 6.1 Mbp, as assessed using the Oxford Nanopore platform, and its genomic DNA G+C content was 43.0 mol%. The major fatty acids of strain I65T were iso-C15 : 0 and iso-C15 : 1 G, and the major respiratory quinone was MK-7. Moreover, the major polar lipid of strain I65T was phosphatidylethanolamine. Based on genotypic, chemotaxonomic, and phenotype data, strain I65T represents a novel species belonging to the genus Niabella, for which the name Niabella defluvii sp. nov. is proposed. The type strain is I65T (=KACC 22647T=JCM 35315T).

Microbial Succession on Microplastics in Wastewater Treatment Plants: Exploring the Complexities of Microplastic-Microbiome Interactions.

Despite some effectiveness of wastewater treatment processes, microplastics accumulate in sewage sludge and their further use may contribute to the release of plastic microplastics into the environment. There is an urgent need to reduce the amount of microplastics in sewage sludge. Plastic particles serve as solid substrates for various microorganisms, promoting the formation of microbial biofilms with different metabolic activities. The biofilm environment associated with microplastics will determine the efficiency of treatment processes, especially biological methods, and the mechanisms of organic compound conversion. A significant source of microplastics is the land application of sewage sludge from wastewater treatment plants. The detrimental impact of microplastics affects soil enzymatic activity, soil microorganisms, flora, fauna, and plant production. This review article summarizes the development of research related to microplastics and discusses the issue of microplastic introduction from sewage sludge. Given that microplastics can contain complex composite polymers and form a plastisphere, further research is needed to understand their potential environmental impact, pathogenicity, and the characteristics of biofilms in wastewater treatment systems. The article also discusses the physicochemical properties of microplastics in wastewater treatment plants and their role in biofilm formation. Then, the article explained the impact of these properties on the possibility of the formation of biofilms on their surface due to the peculiar structure of microorganisms and also characterized what factors enable the formation of specific plastisphere in wastewater treatment plants. It highlights the urgent need to understand the basic information about microplastics to assess environmental toxicity more rationally, enabling better pollution control and the development of regulatory standards to manage microplastics entering the environment.

Discovering Novel Organophosphorus Compounds in Wastewater Treatment Plant Effluents through Suspect Screening and Nontarget Analysis.

Limited knowledge on the structure of emerging organophosphorus compounds (OPCs) hampers our comprehensive understanding of their environmental occurrence and potential risks. Through suspect and nontarget screening, combining data-dependent acquisition, data-independent acquisition, and parallel reaction monitoring modes, we identified 60 OPCs (17 traditional and 43 emerging compounds) in effluents of 14 wastewater treatment plants (WWTPs) in Beijing and Qinghai, China. These OPCs comprise 26 organophosphate triesters, 17 organophosphate diesters, 6 organophosphonates, 7 organothiophosphate esters, and 4 other OPCs. Notably, 14 suspect OPCs were newly identified in WWTP effluents, and 16 nontarget OPCs were newly discovered in environmental matrices. Specifically, the cyclic phosphonate, (5-ethyl-2-methyl-1,3,2-dioxaphosphorinan-5-yl)methyl dimethyl phosphonate P-oxide (PMMMPn), consistently appeared in all WWTP effluents, with semiquantitative concentrations ranging from 44.4 to 282 ng/L. Its analogue, di-PMMMPn, presented in 93% of wastewater samples. Compositional differences between the WWTP effluents of two cities were mainly attributed to emerging OPCs. Hazard and ecological risk assessment underscored the substantial contribution of chlorinated organophosphate esters and organothiophosphate esters to overall risks of OPCs in WWTP effluents. This study provides the most comprehensive OPC profiles in WWTP effluents to date, highlighting the need for further research on their occurrence, fate, and risks, particularly for chlorinated OPCs.

Machine Learning-Assisted Optimization of Mixed Carbon Source Compositions for High-Performance Denitrification.

Appropriate mixed carbon sources have great potential to enhance denitrification efficiency and reduce operational costs in municipal wastewater treatment plants (WWTPs). However, traditional methods struggle to efficiently select the optimal mixture due to the variety of compositions. Herein, we developed a machine learning-assisted high-throughput method enabling WWTPs to rapidly identify and optimize mixed carbon sources. Taking a local WWTP as an example, a mixed carbon source denitrification data set was established via a high-throughput method and employed to train a machine learning model. The composition of carbon sources and the types of inoculated sludge served as input variables. The XGBoost algorithm was employed to predict the total nitrogen removal rate and microbial growth, thereby aiding in the assessment of the denitrification potential. The predicted carbon sources exhibited an enhanced denitrification potential over single carbon sources in both kinetic experiments and long-term reactor operations. Model feature analysis shows that the cumulative effect and interaction among individual carbon sources in a mixture significantly enhance the overall denitrification potential. Metagenomic analysis reveals that the mixed carbon sources increased the diversity and complexity of denitrifying bacterial ecological networks in WWTPs. This work offers an efficient method for WWTPs to optimize mixed carbon source compositions and provides new insights into the mechanism behind enhanced denitrification under a supply of multiple carbon sources.

Occurrence, distribution, and ecological risk assessment of pharmaceuticals and personal care products in the surface water of Lipu River, China.

Pharmaceuticals and Personal Care Products (PPCPs) are inadvertently released into the aquatic environment, causing detrimental effects on aquatic ecosystem. There is an urgent need of an in-deep investigation on contamination information of PPCPs in aquatic environment as well as the ecological risks to the aquatic ecosystem. This study was carried out in Lipu River basin, China, to investigate the distribution pattern and ecological risks of PPCPs. Results showed that PPCPs pollution is ubiquitous, 29 out of 30 targeted PPCPs were detected in Lipu River. Fourteen PPCPs were detected with a frequency of 100% in all water samples, and ten PPCPs were detected with a frequency of more than 80%. The cumulated PPCPs concentrations ranged from 33.30 ng/L to 99.60 ng/L, with a median value of 47.20 ng/L in Lipu River. Caffeine, flumequine, nifedipine, and lomefloxacin were the predominant PPCPs in study area. Caffeine showed high ecological risk, five and seven individual PPCP showed medium and low ecological risk to algae.

Occurrence and fate of five representative neonicotinoid insecticides across different wastewater treatment plants and the impact on receiving water bodies.

Neonicotinoids (NEOs), despite their widespread use as insecticides, exhibit a notable knowledge deficit in regards to their presence in wastewater treatment plants (WWTPs) and their surrounding environments. This study delves into the presence and disposition of 5 NEOs: Thiamethoxam (THM), Clothianidin (CLO), Imidacloprid (IMD), Acetamiprid (ACE), and Thiacloprid (THA) across 3 domestic WWTPs and their receiving waters. Notably, THM, CLO, and ACE were consistently detected in all water and sludge samples, with THM emerging as the most abundant compound in both influent and effluent. Among the 3 WWTPs, WWTP 2, employing a fine bubble oxidation process, achieved the highest removal efficiency, surpassing 68%, in contrast to WWTP 1 (CAST) at 37% and WWTP 3 (A/A/O) at 7%. Biodegradation played a pivotal role in NEO removal, accounting for 36.7% and 68.2% of the total removal in WWTP 1 and WWTP 2, respectively. Surprisingly, in WWTP 3, biotransformation process inadvertently increased ACE and CLO concentrations by approximately 4.1% and 4.5%, respectively. The total NEO concentration in the receiving surface waters ranged from 72.7 to 155.5 ng/L, while sediment concentrations were significantly lower, spanning between 0.10 and 1.53 ng/g. WWTPs serve as both a removal and concentration point for NEOs, thereby significantly influencing their transportation. Additionally, the concentration of most NEOs in the receiving waters progressively increased from upstream to downstream, highlighting the substantial impact of WWTP discharges on natural water environments. This research offers valuable insights into NEO pollution surrounding WWTPs in the Pearl River Delta, ultimately aiding in pollution control and environmental protection decisions.

Assessment of seasonal and annual patterns in phosphorus content in a monitored catchment through a partitioning approach based on hydrometeorological data.

High amounts of phosphorus (P) in rivers come mainly from two sources: fertilizers washed off from agricultural and urban areas by runoff water (non-point sources) and urban and industrial development which are translated in P discharges from wastewater treatment plants (WWTP). This work analyses the content of P in water for nearly 40 years inquiring into the origin of the sources, based on the hypothesis of runoff generation from the detection of river streamflow increases during the P contribution episode and the previous precipitation. For this purpose, the Guadaira River, which is located in the South of Spain and has a drainage surface of 1524 km2, was selected. In this watershed agricultural land use converges with numerous human activities resulting in high pressures on water quality. We found 40% of the P contribution episodes found seem to come from the runoff generated after the heaviest rainfall events, which normally occur between November and May. The remaining 60% of the P contribution episodes were found to be linked to point sources, which become more relevant from June to September, reaching the highest concentration values (6-17 mg/L). The results highlight that the target phosphate concentration value of 0.34 mg PO4/L imposed by the national legislation for a good state following the Water Framework Directive 2000/60/EC is exceeded by 96% of the measurements during the period from 1981 to 2022. On a monthly basis, PO4 loads showed a linear relationship with river streamflow (R2 = 0.94). However, on field measurements scale, a potential relationship between both variables was found, which changed according to the improvement in the wastewater treatment and facilities for 1982-1994, 1995-2017 and 2018-2022. In these three periods, different significant decreasing trends of the P content were found, mainly marked by the setup of each individual WWTP.

Evaluation of pharmaceutical consumption between urban and suburban catchments in China by wastewater-based epidemiology.

Wastewater-based epidemiology (WBE) is amply used for estimating human consumption of chemicals, yet information on regional variation of pharmaceuticals and their environmental fate are scarce. Thus, this study aims to estimate the consumption of three cardiovascular, four non-steroidal anti-inflammatory pharmaceuticals (NSAIDs), and four psychoactive pharmaceuticals between urban and suburban catchments in China by WBE, and to explore their removal efficiencies and ecological risks. Eleven analytes were detected in both influent and effluent samples. The estimated consumptions ranged from

Evaluation of the production and extraction of polyhydroxybutyrate from volatile fatty acids by means of mixed cultures and B. cepacia.

The global consumption of plastics generates accelerated environmental pollution in landfills and marine ecosystems. Biopolymers are the materials with the greatest potential to replace synthetic polymers in the market due to their good biodegradability, however, there are still several disadvantages, mainly related to their production cost. Considering the above, the generation of biodegradable and biocompatible bioplastics stands out as an alternative solution, some of which are made from renewable raw materials, including polyhydroxyalkanoates PHAs. Although much research has been done on bacteria with the capacity for intracellular accumulation of PHAs, among others, it is also possible to produce PHAs using mixed microbial cultures instead of a single microorganism, using natural microbial consortia that have the capacity to store high amounts of PHAs. In this contribution, three methods for the extraction and purification of PHAs produced by fermentation using volatile fatty acids as a carbon source at different concentrations were evaluated, using the pure strain Burkholderia cepacia 2G-57 and the mixed cultures of the activated sludge from the El Salitre WWTP, in order to select the best method from the point of view of environmental sustainability as this will contribute to the scalability of the process. The mixed cultures were identified by sequencing of the 16S gene. A yield of 89% was obtained from the extraction and purification of PHA using acetic acid as a solvent, which according to its properties is "greener" than chloroform. The polymer obtained was identified as polyhydroxybutylated PHB.

Monitoring (micro-)pollutants in wastewater treatment plants: comparing discharges in wet- and dry-weather.

Municipal wastewater treatment plants (WWTPs) are crucial for maintaining good quality of surface water, limiting environmental pollution. However, during wet-weather events, WWTPs become an important point-source discharge due to the activation of the bypass, which releases a mix of untreated wastewater and stormwater. This work aims to assess how the WWTP discharges (effluent and bypass) impact on the receiving surface water body during dry- and wet-weather, monitoring 78 pollutants (7 conventional pollutants, 19 heavy metals, and 52 micropollutants) in each stream (effluent during dry-weather, effluent and bypass during wet-weather), including the influent in dry-weather for comparison. The occurrence, concentration levels and variability, and environmental risk were addressed, with a specific focus on high-resolution (up to 20-minutes) sampling of the bypass, based on the expected relevant temporal dynamicity. A wider range of pollutants occurred in the bypass, included undetected compounds in the dry-weather influent. Besides, a greater inter-events variability in bypass concentrations was observed, but smaller intra-event variability, with only some pollutants exhibiting a distinct first-flush effect. To address the challenge of a cost-effective bypass monitoring, we explored the applicability of readily measurable water quality parameters (total suspended solids and electrical conductivity) as proxies for micropollutants. Correlations between these parameters and specific pollutant groups suggest a promising path for further investigation and broader application. The magnitude of the rain event also affected concentration levels, with event volume clearly affecting pollutants dilution. The environmental risk assessment revealed a significantly higher risk associated to bypass discharge compared to the effluent, especially for conventional pollutants and metals, highlighting the urgency of improved bypass management strategies. Overall, this study highlights the contribution of wet-weather discharges from WWTPs, emphasizing the importance of high-frequency bypass monitoring to capture peak pollutant concentrations and accurately assess the environmental risk.

Viral community distribution, assembly mechanism, and associated hosts in an industrial park wastewater treatment plant.

Viruses manipulate bacterial community composition and impact wastewater treatment efficiency. Some viruses pose threats to the environment and human populations through infection. Improving the efficiency of wastewater treatment and ensuring the health of the effluent and receptor pools requires an understanding of how viral communities assemble and interact with hosts in wastewater treatment plants (WWTPs). We used metagenomic analysis to study the distribution, assembly mechanism, and sensitive hosts for the viral communities in raw water, anaerobic tanks, and returned activated sludge units of a large-scale industrial park WWTP. Uroviricota (53.42% ± 0.14%) and Nucleocytoviricota (26.1% ± 0.19%) were dominant in all units. Viral community composition significantly differed between units, as measured by ß diversity (P = 0.005). Compared to raw water, the relative viral abundance decreased by 29.8% in the anaerobic tank but increased by 9.9% in the activated sludge. Viral community assembly in raw water and anaerobic tanks was predominantly driven by deterministic processes (MST <0.5) versus stochastic processes (MST >0.5) in the activated sludge, indicating that differences in diffusion limits may fundamentally alter the assembly mechanisms of viral communities between the solid and liquid-phase environments. Acidobacteria was identified as the sensitive host contributing to viral abundance, exhibiting strong interactions and a mutual dependence (degree = 59). These results demonstrate the occurrence and prevalence of viruses in WWTPs, their different assembly mechanism, and sensitive hosts. These observations require further study of the mechanisms of viral community succession, ecological function, and roles in the successive wastewater treatment units.

Ecological and functional differences of abundant and rare sub-communities in wastewater treatment plants across China.

The microbial community in activated sludge is composed of a small number of abundant sub-community with high abundance and a large number of rare sub-community with limited abundance. Our knowledge regarding the ecological properties of both abundant and rare sub-communities in activated sludge is limited. This article presented an analysis of functional prediction, assembly mechanisms, and biogeographic distribution characteristics of abundant and rare sub-communities in 211 activated sludge samples from 60 wastewater treatment plants across China. Moreover, this study investigated the dominant factors influencing the community structure of these two microbial groups. The results showed that the functions associated with carbon and nitrogen cycling were primarily detected in abundant sub-community, while rare sub-community were primarily involved in sulfur cycling. Both microbial groups were mainly influenced by dispersal limitation, which, to some extent, resulted in a distance-decay relationship in their biogeographic distribution. Moreover, a higher spatial turnover rate of rare sub-communities (0.0887) suggested that spatial differences in microbial community structure among different WWTPs may mainly result from rare sub-community. Moreover, SEM showed that geographic locations affected rare sub-communities greatly, which agreed with their higher dispersal limitation and turnover rate. In contrast, influent characteristics showed stronger correlations with abundant sub-communities, suggesting that abundant sub-community may contribute more to the removal of pollutants. This study enhanced our understanding of abundant and rare microorganisms in activated sludge especially the role of rare species and provided scientific evidence for precise regulation and control of wastewater treatment plants.

Microbiological toxicity tests using standardized ISO/OECD methods-current state and outlook.

Microbial toxicity tests play an important role in various scientific and technical fields including the risk assessment of chemical compounds in the environment. There is a large battery of normalized tests available that have been standardized by ISO (International Organization for Standardization) and OECD (Organization for Economic Co-operation and Development) and which are worldwide accepted and applied. The focus of this review is to provide information on microbial toxicity tests, which are used to elucidate effects in other laboratory tests such as biodegradation tests, and for the prediction of effects in natural and technical aqueous compartments in the environment. The various standardized tests as well as not normalized methods are described and their advantages and disadvantages are discussed. In addition, the sensitivity and usefulness of such tests including a short comparison with other ecotoxicological tests is presented. Moreover, the far-reaching influence of microbial toxicity tests on biodegradation tests is also demonstrated. A new concept of the physiological potential of an inoculum (PPI) consisting of microbial toxicity tests whose results are expressed as a chemical resistance potential (CRP) and the biodegradation adaptation potential (BAP) of an inoculum is described that may be helpful to characterize inocula used for biodegradation tests. KEY POINTS: • Microbial toxicity tests standardized by ISO and OECD have large differences in sensitivity and applicability. • Standardized microbial toxicity tests in combination with biodegradability tests open a new way to characterize inocula for biodegradation tests. • Standardized microbial toxicity tests together with ecotoxicity tests can form a very effective toolbox for the characterization of toxic effects of chemicals.

Succession from acetoclastic to hydrogenotrophic microbial community during sewage sludge anaerobic digestion for bioenergy production.

To assess microbial dynamics during anaerobic digestion (AD) of sewage sludge (SWS) from a municipal Wastewater Treatment Plant (WWTP), a Biochemical Methane Potential (BMP) assay at 37 °C under mono-digestion conditions was conducted. Utilizing the Illumina MiSeq platform, 16S ribosomal RNA (rRNA) gene sequencing unveiled a core bacterial community in the solid material, showcasing notable variations in profiles. The research investigates changes in microbial communities and metabolic pathways to understand their impact on the efficiency of the digestion process. Prior to AD, the relative abundance in SWS was as follows: Proteobacteria > Bacteroidota > Actinobacteriota. Post-AD, the relative abundance shifted to Firmicutes > Synergistota > Proteobacteria, with Sporanaerobacter and Clostridium emerging as dominant genera. Notably, the methanogenic community underwent a metabolic pathway shift from acetoclastic to hydrogenotrophic in the lab-scale reactors. At the genus level, Methanosaeta, Methanolinea, and Methanofastidiosum predominated initially, while post-AD, Methanobacterium, Methanosaeta, and Methanospirillum took precedence. This metabolic transition may be linked to the increased abundance of Firmicutes, particularly Clostridia, which harbor acetate-oxidizing bacteria facilitating the conversion of acetate to hydrogen.

Carbon performance analysis of upgraded wastewater treatment plants in key control areas of the Ziya River Basin in China.

Wastewater treatment plants (WWTPs) are one of the largest sources of greenhouse gas (GHG) emissions, and they are also one of the largest energy consumption industries in urban systems. With the progression of upgrading and standard-rising, WWTPs both directly and indirectly increase carbon emissions from the increased investments in facilities and usages in electricity as well as chemical agents. Here, we collected operational data from 15 WWTPs in the key control areas of the Ziya River Basin in North China and accounted for the changes in carbon performance at different technical upgrade methods. Results showed that the average carbon emission performance increased by 0.487 kg CO2/m3 after the upgrade. Carbon emissions from electricity consumption, chemical usage, biochemical process and sludge treatment accounted for 42%, 17%, 24%, and 17% of the total improvement in carbon emission performance, respectively. Reducing energy consumption, regulating chemical use and sludge comprehensive utilization are the key to carbon emission reduction. It further proposes that the development of wastewater treatment discharge standards should fully consider the comprehensive utilization of water quality classification. Regions with favorable natural conditions should make full use of their advantages by adopting economically feasible, low-energy-consuming technologies such as constructed wetlands, which offer carbon sequestration and landscaping benefits. This study provides guidance on the selection of technological pathways for pollution reduction and carbon mitigation in the wastewater treatment industry and on achieving sustainable water resource utilization.

Novel extended hybrid tool for real time control and practically support decisions to reduce GHG emissions in full scale wastewater treatment plants.

In this paper, a novel methodology and extended hybrid model for the real time control, prediction and reduction of direct emissions of greenhouse gases (GHGs) from wastewater treatment plants (WWTPs) is proposed to overcome the lack of long-term data availability in several full-scale case studies. A mechanistic model (MCM) and a machine learning (ML) model are combined to real time control, predict the emissions of nitrous oxide (N2O) and carbon dioxide (CO2) as well as effluent quality (COD - chemical oxygen demand, NH4-N - ammonia, NO3-N - nitrate) in activated sludge method. For methane (CH4), using the MCM model, predictions are performed on the input data (VFA, CODs for aerobic and anaerobic compartments) to the MLM model. Additionally, scenarios were analyzed to assess and reduce the GHGs emissions related to the biological processes. A real WWTP, with a population equivalent (PE) of 125,000, was studied for the validation of the hybrid model. A global sensitivity analysis (GSA) of the MCM and a ML model were implemented to assess GHGs emission mechanisms the biological reactor. Finally, an early warning tool for the prediction of GHGs errors was implemented to assess the accuracy and the reliability of the proposed algorithm. The results could support the wastewater treatment plant operators to evaluate possible mitigation scenarios (MS) that can reduce direct GHG emissions from WWTPs by up to 21%, while maintaining the final quality standard of the treated effluent.

Bioaerosol emissions from wastewater treatment process at urban environment and potential health impacts.

The inlet of wastewater treatment plants (WWTPs) contains pathogenic microorganisms which during aeration and by mechanical mixing through wind typically aerosolized microbes into ambient air. Bioaerosol emission and its characterization (bacterial and fungal) was investigated considering low-flow and high-flow inlet of wastewater treatment plant. Generation of bioaerosols was found influenced by prevailing seasons while both during summer and winter, fungal concentration (winter: 1406 ± 517; summer: 1743 ± 271 CFU/m3) was higher compared to bacterial concentration (winter: 1077 ± 460; summer: 1415 ± 588 CFU/m3). Bioaerosols produced from WWTPs were predominately in the size range of 2.1-4.7 µm while fraction of fungal bioaerosols were also in ultra-fine range (0.65 µm). Bioaerosols reaching to the air from WWTPs varied seasonally and was calculated by aerosolization ratio. During summer, aerosolization of the bioaerosols was nearly 6 times higher than winter. To constitute potential health effects from the exposure to these bioaerosols, biological characterization, antibiotics resistance and the health survey of the nearby area were also performed. The biological characterization of the bioaerosols samples were done through metagenomic approach using 16s and ITS metagenomic sequencing. Presence of 167 genus of bacteria and 41 genus of fungi has been found. Out of this, bacillus (73%), curtobacterium (21%), pseudomonas, Exiguo bacterium, Acinetobacter bacillaceae, Enterobacteriaceae and Prevotella were the dominant genus (top 10) of bacteria. In case of fungi, xylariales (49%), Hypocreales (19%), Coperinopsis (9%), Alternaria (8%), Fusarium (6%), Biopolaris, Epicoccum, Pleosporaceae, Cladosporium and Nectriaceae were dominant. Antibiotics like, Azithromycin and cefixime were tested on the most dominant bacillus showed resistance on higher concentration of cefixime and lower concentration of azithromycin. Population-based health survey in WWTP nearby areas (50-150 m periphery) found several types of diseases/symptoms including respiratory problem, skin rash/irritation, change in smell and taste, eye irritation within the resident population and workers.

Microbial nutrient recovery cell as an efficient and sustainable nutrient recovery option in sewage treatment.

Globally, nutrient pollution is a serious and challenging concern. Wastewater treatment plants (WWTPs) are designed to prevent the discharge of contaminants resulting from anthropogenic sources to the receiving water bodies. In this study, seasonal nutrient pollution load, and biological nutrient removal efficiency of an anoxic aerobic unit based WWTP were investigated. Seasonal assessment revealed that the average total nitrogen removal efficiency and total phosphorus removal efficiency of the WWTP do not meet the discharge standard of 10 mg/L and 1 mg/L, respectively. Furthermore, the WWTP does not utilize the energy contained in the wastewater. In this regard, dual chamber MFC (D-MFC) has emerged as a promising solution that can not only treat wastewater but can also convert chemical energy present in the wastewater into electrical energy. However, higher N O3- (57 ± 4 mg/L) and P-P O43- (6 ± 0.52 mg/L) concentration in cathodic effluent is a major drawback in D-MFC. Therefore, to solve this issue, D-MFC was transformed into a microbial nutrient recovery cell (MNRC) which demonstrated a final N H4+-N and P-P O43- concentration of nearly 1 mg/L with N H4+-N and P-P O43- recovery up to 74 % and 69 %, respectively in the recovery chamber. Besides, MNRC attained a maximum power density of 307 mW/m3 and a current density of 1614 mA/m3, thus indicating MNRC is an eco-friendly, energy-neutral, and promising technology for electricity generation and recovering nutrients.

Complete long-term monitoring of greenhouse gas emissions from a full-scale industrial wastewater treatment plant with different cover configurations.

The greenhouse gas (GHG) emissions from wastewater treatment plants (WWTPs), consisting mainly of methane (CH4) and nitrous oxide (N2O), have been constantly increasing and become a non-negligible contributor towards carbon neutrality. The precise evaluation of plant-specific GHG emissions, however, remains challenging. The current assessment approach is based on the product of influent load and emission factor (EF), of which the latter is quite often a single value with huge uncertainty. In particular, the latest default Tier 1 value of N2O EF, 0.016 ± 0.012 kgN2O-N kgTN-1, is estimated based on the measurement of 30 municipal WWTPs only, without involving any industrial wastewater. Therefore, to resolve the pattern of GHG emissions from industrial WWTPs, this work conducted a 14-month monitoring campaign covering all the process units at a full-scale industrial WWTP in Shanghai, China. The total CH4 and N2O emissions from the whole plant were, on average, 447.7 ± 224.5 kgCO2-eq d-1 and 1605.3 ± 2491.0 kgCO2-eq d-1, respectively, exhibiting a 5.2- or 3.9-times more significant deviation than the influent loads of chemical oxygen demand (COD) or total nitrogen (TN). The resulting EFs, 0.00072 kgCH4 kgCOD-1 and 0.00211 kgN2O-N kgTN-1, were just 0.36% of the IPCC recommended value for CH4, and 13.2% for N2O. Besides, the parallel anoxic-oxic (A/O) lines of this industrial WWTP were covered in two configurations, allowing the comparison of GHG emissions from different odor control setup. Unit-specific analysis showed that the replacement of enclosed A/open O with enclosed A/O reduced the CH4 EF by three times, from 0.00159 to 0.00051 kgCH4 kgCOD-1, and dramatically decreased the N2O EF by an order of magnitude, from 0.00376 to 0.00032 kgN2O-N kgTN-1, which was among the lowest of all full-scale WWTPs.

Lessons learned from a one-year study of Legionella spp. cultivation from activated sludge samples.

Risk assessment and management of Legionella spp. contamination in activated sludge in wastewater treatment plants is carried out using the culture method. Underestimation of Legionella spp. is frequently reported in the literature, but a comprehensive long-term study of the performance of the method under comparable conditions is still lacking. The aim of this study is to evaluate the recovery rate and limit of detection of the culture method for Legionella spp. from activated sludge samples collected during the different seasons of the year. Activated sludge samples spiked with Legionella pneumophila subsp. pneumophila strain Philadelphia-1 (mean concentration 5.2 ± 0.35 logCFU/mL) were analysed monthly for one year using the culture method. Three different sample pre-treatments were compared, namely filtration, acid treatment and thermal treatment, and the recovery rate and limit of detection were assessed for each. The recovery rate of the culture method for Legionella spp. depended on the type of sample pre-treatment and the season of activated sludge sampling, while the limit of detection depended only on the sample pre-treatment. The best performance of the culture method, defined as the combination of the highest recovery rate and lowest limit of detection, was obtained for the filtered acid pre-treated samples (recovery rate: 89 ± 4 %; limit of detection: 1.3 logCFU/mL in 83 % of the samples). The lowest limit of detection was observed for the filtered thermally pre-treated samples (1.0 logCFU/mL in 93 % of the samples). Simultaneously, both thermally pre-treated samples showed up to a third lower recovery rates than the other pre-treatments in winter, while untreated and acid pre-treated samples showed consistently high recovery rates (>80%, logCFU/mL). The recovery rates of the unfiltered and filtered thermally pre-treated samples showed significant weak to strong positive correlations with the organic and phosphorus load in the influent as well as with the water and atmospheric temperatures, indicating that the recovery rate depends on the seasonal variation of the wastewater composition. This study presents new insights into the detection and quantification of Legionella spp. in activated sludge samples and considers seasonal dependencies in analytical results.