Microbiology of post-fermentation leachate

<p>Inadequate management of plastic waste has resulted in its ubiquity within the environment, and presents a risk to living organisms. Harm caused by large plastics is well documented, but progressive understanding of microplastics (< 5mm) reveals an ever more unsettling issue. Microplastics contamination is considered an emerging global multidisciplinary issue that would be aided by further research on sources, distribution, abundance, and transport mechanisms. Landfills are a suspected source of such, but research at these sites is insufficient. Although the risks surrounding microplastics are still inconclusive, there is concern over their accumulation in organisms, leaching constituents, and hydrophobic nature. Studying microplastics in the environment, let alone landfill, is challenging as standard and accepted methodologies are presently non-existent.</p><p>Here, microplastics (1mm to 25µm) were evaluated at one particular and long-running UK landfill after first developing a simple, replicable, efficient, and cost effective sampling and analysis approach. Concentrations and types of microplastics were quantified in raw leachate, treated leachate, waste water, groundwater, and surface water, to characterise abundance, distribution, and released loads to the environment. Samples were filtered in-situ, with subsequent purification at the laboratory by Fenton’s reagent. Analysis relied heavily on microscopic sorting and counting, but use of Scanning Electron Microscopy – Energy Dispersive X-Ray Spectroscopy enabled instrumental interrogation of particles suspected to be plastic. Many factors investigated here appear novel to the literature, and comprehensively explore: temporal variation of microplastics in raw leachate across different landfill phases and waste ages; their abundance in local groundwater, and surface water discharge; microplastics distribution within a leachate treatment plant; and their subsequent release to the environment from a waste water treatment facility. The results build upon the small collection of existing work, but also offer new insights into microplastics’ occurrence in, around, and released from a landfill site.</p><p>In total, 62 samples were taken, and particles considered microplastics (MP) were most abundant in groundwater, followed by raw leachate > waste water > treated leachate > surface water. Average concentration in groundwater was 105.1±104.3 MP L<sup>-1</sup>, raw leachate 3.3±1.7 MP L<sup>-1</sup>, and waste water was 1.8±0.73 MP L<sup>-1</sup>. Consistent with other research, fibres were most dominant, but blank samples highlight the great potential for secondary contamination. Imaging of suspect particles revealed the extreme nature and conditions of landfill sites in their generation of microplastics. Analogous to waste water treatment, leachate treatment is shown to be reducing microplastics in the discharge by 58.1%, and it is expected that microplastics are retained in the treatment plant sludge. Daily loads from leachate treatment were 142,558±67,744 MP day<sup>-1</sup>, but from waste water this was approximately 45.2±18.3 million MP day<sup>-1</sup>. Ultimately, the landfill is not a final sink of microplastics but a source, for those >25 µm, to the environment: yet, it is unlikely to be a significant one. Results highlighted the need for reduction strategies at waste water treatment plants and in the site’s groundwater boreholes, as well as further investigation to determine the source of abundant fibres in the surface water.</p>

On a deeper understanding of data-driven approaches in the current framework of wastewater treatment: looking inside the black-box

Municipal wastewater treatment plants (WWTPs) in Gauteng, South Africa, are inadequately designed or optimized to effectively remove microplastics (MPs), resulting in approximately 80% of wastewater being discharged into aquatic ecosystems with insufficient treatment. This study evaluates the prevalence and abundance of MPs in municipal WWTPs and their subsequent introduction into receiving water bodies. Comprehensive sampling was conducted across three municipal WWTPs in the Emfuleni region of Gauteng province from October 2022 to July 2023. Initial MP identification and quantification were performed using light microscopy, while scanning electron microscope energy-dispersive X-ray spectroscopy (SEM/EDS) was employed to identify non-plastic particles and perform elemental analysis. The findings reveal significant seasonal variability in MP concentrations. The highest influent and effluent concentrations were recorded during October (spring), with influent values of 142 MPs/ℓ (WWTP 1), 124 MPs/ℓ (WWTP 2), and 132 MPs/ℓ (WWTP 3), and effluent concentrations of 120 MPs/ℓ (WWTP 1), 63 MPs/ℓ (WWTP 2), and 89 MPs/ℓ (WWTP 3). Conversely, the lowest MP concentrations were observed during April (autumn), with influent concentrations of 114 MPs/ℓ (WWTP 1), 141 MPs/ℓ (WWTP 2), and 78 MPs/ℓ (WWTP 3), and effluent concentrations of 99 MPs/ℓ (WWTP 1), 53 MPs/ℓ (WWTP 2), and 86 MPs/ℓ (WWTP 3). Fibers and filaments constituted the dominant MP morphology, primarily derived from polyester, nylon, and acrylic synthetic textiles. Dark-colored MPs, especially black, blue, and red particles, were predominant in the wastewater samples. This study underscores the critical role of WWTPs as conduits for MP contaminants into the environment and highlights the urgent need to develop and implement improved MP removal technologies in wastewater treatment systems. MP production is estimated to account for approximately 15–20% of total global plastic production, corresponding to an annual generation of approximately 52.5–80 million metric tons of MP. By addressing MP pollution, this research directly contributes to sustainability by promoting the protection of freshwater ecosystems, reducing anthropogenic pressures on aquatic biodiversity, and supporting the principles of sustainable development. The findings align with global and regional goals to enhance water quality management and promote sustainable urbanization practices in line with the United Nations Sustainable Development Goals (SDGs).

Advanced wastewater treatment processes and novel technologies are adopted to improve nutrient removal from wastewater so as to meet stringent discharge standards. Municipal wastewater treatment plants are one of the major contributors to the increase in the global greenhouse gas (GHG) emissions and therefore it is necessary to carry out intensive studies on quantification, assessment and characterization of GHG emissions in wastewater treatment plants, on the life cycle assessment from GHG emission prospective, and on the GHG mitigation strategies. Greenhouse Gas Emission and Mitigation in Municipal Wastewater Treatment Plants summarises the recent development in studies of greenhouse gases’ (CH4 and N2O) generation and emission in municipal wastewater treatment plants. It introduces the concepts of direct emission and indirect emission, and the mechanisms of GHG generations in wastewater treatment plants’ processing units. The book explicitly describes the techniques used to quantify direct GHG emissions in wastewater treatment plants and the protocol used by the Intergovernmental Panel on Climate Change (IPCC) to estimate GHG emission due to wastewater treatment in the national GHG inventory. Finally, the book explains the life cycle assessment (LCA) methodology on GHG emissions in consideration of the energy and chemical usage in municipal wastewater treatment plants. In addition, the strategies to mitigate GHG emissions are discussed. The book provides an overview for researchers, students, water professionals and policy makers on GHG emission and mitigation in municipal wastewater treatment plants and industrial wastewater treatment processes. It is a valuable resource for undergraduate and postgraduate students in the water, climate, and energy areas; for researchers in the relevant areas; and for professional reference by water professionals, government policy makers, and research institutes. ISBN: 9781780406305 (Print) ISBN: 9781780406312 (eBook) ISBN: 9781780409054 (ePUB)

Water scarcity is a global challenge faced by millions of people, and it has a negative impact on the ecosystem, public health, and financial stability. Water demand and supply management becomes critical, especially in areas with limited access to clean, safe water. Wastewater and water treatment infrastructure is essential for maintaining environmental integrity and protecting human health. However, water treatment plants in South Africa face various complex obstacles brought on by institutional setups, practical limitations, and environmental concerns, including water quality. This study investigated the institutional arrangements, operational challenges, and environmental concerns that water and wastewater treatment plants face in the Vhembe District Municipality, South Africa. A qualitative study was conducted in Limpopo province, where employees from 12 water and wastewater treatment plants were interviewed, and the data were analyzed thematically. The data were arranged into five major themes using thematic analysis: understanding water and wastewater treatment systems, educational and demographic profile, water quality assessment, operational performance and regulatory compliance, and water volume in waterworks plants. Staff attitudes, institutional and operational challenges, and the current condition of treatment plants were all comprehensively portrayed using Ostrom’s IAD Framework. It was found that workers generally understand water treatment processes, but inconsistencies and a lack of transparency in monitoring water quality were noted, with many parameters from SANS 241 not being tested consistently. A significant educational gap among workers was also observed. Insufficient capacity, load-shedding, limited resources, and inadequate infrastructure prevented treatment plants from meeting daily water needs, worsened by institutional and socio-economic factors. Similar challenges were noted in countries like China, Ethiopia, India, Pakistan, Malaysia, Brazil, and Libya. To enhance water management efficiency and compliance, the study recommends more training, standardized procedures, proactive maintenance, and stakeholder involvement.

Total concentrations and fractions of Cd, Cr, Pb, Cu, Ni and Zn in sewage sludge from municipal and industrial wastewater treatment plants

Towards circular food production systems: Identification of chemical, microbial, and physical food safety hazards in municipal sludge and excess aerobic biomass of the food industry.

BackgroundThe management of sludge from municipal wastewater treatment plants (WWTPs) is a global issue, but also an opportunity for circular reuse. Recent data show that sludge reuse in agriculture has the highest share of all utilization routes in the EU. Council Directive 86/278/EEC on the spreading of sludge in agriculture, adopted more than 35 years ago, is still relevant, notwithstanding the discussion on the need to update it. Extracting critical, strategic, and precious metals and metalloids from sludge is an alternative for sludge reuse, which offers several benefits, such as avoiding the high environmental and health risks associated with using sludge directly in agriculture. Additionally, it allows for the recovery of metals, including those listed as Critical Raw Materials by the European Commission. To implement this alternative, it is necessary to first assess the metal content in the sludge and then develop economically and technically viable technologies. In this study, the content of chemical elements in the sludge of eight full-scale WWTPs in Bulgaria is analysed with focus on: (1) assessing the suitability for agricultural application by evaluating the content of macro- and micronutrients and hazardous metals; (2) assessing the possibility of using the sludge as a source of critical and precious metals.ResultsFor the main nutrients, the following contents as a percentage of the sludge dry weight (DW) were recorded—2.06% to 6% for N, 1.52% to 2.67% for P and 0.47% to 0.81% for K, which are in line with case studies of successful sludge application in agriculture. Only sludge samples from two WWTPs exceeded the permitted limit for hazardous metals and metalloids. On the other hand, of the 21 metal and metalloid constituents listed in the EU Critical and Strategic Material (CRM) list, at least one of the examined samples has a content above 10 mg/kg for 15 elements. The average contents in mg/kgDW of Au (1.1), Al (19,272.9), Mg (6677.6), Ti (1730.9), Ga (20.9) and As (16.6) measured in the investigated WWTPs are among the highest or second highest reported in other countries.ConclusionsThe results of the study show prospects for optimising and improving the reuse of sewage sludge in Bulgaria. Sewage sludge from most WWTPs has potential for agricultural application due to its high nutrient content. Large amounts of accumulated critical and strategic metals, gold and silver are trapped in Bulgarian sewage sludge, indicating that sewage sludge could be considered an alternative source with high potential for these valuable elements.

Sewage sludge processing and management in small and medium-sized municipal wastewater treatment plant-new technical solution

Perfluorinated compounds (PFCs) have drawn much attention due to their environmental persistence, ubiquitous existence, and bioaccumulation potential. Wastewater treatment plants (WWTPs) are fundamental utilities in cities, playing an important role in preventing water pollution by lowering pollution load in waste waters. However, some of the emerging organic pollutants, like PFCs cannot be efficiently removed by traditional biological technologies in WWTPs, and some even increase in effluents compared to influents due to the incomplete degradation of precursors. Hence, WWTPs are considered to be a main point source in cities for PFCs that enter the aquatic environment. However, the mass flow of PFCs from WWTPs has seldom been analyzed for a whole city. Hence, in the present study, 11 PFCs including series of perfluoroalkyl carboxylic acids (PFCAs, C4-C12) and two perfluoroalkyl sulfonates (PFASs, C6 and C8) were measured in WWTP influents and effluents and sludge samples from six municipal WWTPs in Tianjin, China. Generation and dissipation of the target PFCs during wastewater treatment process and their mass flow in effluents were discussed. All the target PFCs were detected in the six WWTPs, and the total PFC concentration in different WWTPs was highly influenced by the population density and commercial activities of the corresponding catchments. Perfluorooctanoic acid (PFOA) was the predominant PFC in water phase, with concentrations ranging from 20 to 170 ng/L in influents and from 30 to 145 ng/L in effluents. Concentrations of perfluoroalkyl sulfonates decreased substantially in the effluent compared to the influent, which could be attributed to the sorption onto sludge, whereas concentrations of PFOA and some other PFCAs increased in the effluent in some WWTPs due to their weaker sorption onto solids and the incomplete degradation of precursors. Perfluorooctane sulfonic acid (PFOS) was the predominant PFC in sludge samples followed by PFOA, and their concentrations ranged from 42 to 169 g/kg and from 12 to 68 g/kg, respectively. Sludge-wastewater distribution coefficients (log K(d)) ranged from 0.62 to 3.87 L/kg, increasing with carbon chain length of the homologues. The mass flow of some PFCs in the effluent was calculated, and the total mass flow from all the six municipal WWTPs in Tianjin was 26, 47, and 3.5 kg/year for perfluorohexanoic acid, PFOA, and PFOS, respectively.

This paper presents the cost optimization of an urban drainage and wastewater treatment system. The mixed sewer urban drainage (including combined sewer overflows and retention basins), the activated sludge wastewater treatment plant (WWTP), and the permissible loading of the receiving water were optimized simultaneously by the nonlinear programming approach. For this purpose, the integrated optimization model OPTIMALWWT was developed. The economic objective function of the defined investment and operational costs is subjected to rigorous design and ecological constraints. A practical example of the cost optimization of an existing urban drainage and WWTP, located in Slovenia, is presented to demonstrate the efficiency of the proposed method. For each of the two different design approaches, three different optimization cases were carried out for three different technological alternatives. As a result, the optimal technological process was finally selected for the reconstruction of the system, as a result of its suitable costs and operational safety.

Energy, exergy and economic analysis of a novel geothermal energy system for wastewater and sludge treatment

Unaerated feeding alters the fate of dissolved methane during aerobic wastewater treatment

A journey of wastewater to clean hydrogen: A perspective

Microplastics in German paper mills' wastewater and process water treatment plants: Investigation of sources, removal rates, and emissions.