Existing Biogas Plants Research Articles

Trade-offs in biomethane production by substrate mixture optimization under German market conditions

BackgroundNew regulations and market conditions in Germany affect the profitability of biomethane upgrading as a repowering option for existing biogas plants following on-site CHP utilization. These conditions present trade-off challenges between higher sustainability requirements, maintaining production capacity and new revenue opportunities. Optimization methods, such as linear programming (LP), are essential for determining the ideal substrate mixture and profitable solutions amidst multiple market conditions, plant-specific process constraints, and substrate properties.MethodsWe updated a substrate mixture optimization model within an assessment framework for the repowering of existing biogas plants (BGPs), which focuses on the operator’s perspective. By integrating multiple German biomethane markets for various BGPs, we assessed changes in the substrate mixture, GHG emissions, contribution margins, and constraint parameters to derive conclusions for operators and future framework design.ResultsIntegrating market revenues and constraints can increase contribution margins by 12–55%. Additional gains can be achieved by considering multiple markets simultaneously but limited to a few BGPs. The plant-specific LP solution space and used benchmark market are decisive. The former limits the potential of high substrate-specific contribution margins, which has a significantly higher impact than the relation between plant-specific characteristics and process constraints. The advanced fuel market is currently the lead market for biomethane, incentivizing GHG-emission extensive substrates, decreasing gas production and GHG emissions but increasing levelized cost of energy (LCOE) and partially CO2 abatement costs.ConclusionsThe key to improve profitability and to supply an increasing biomethane demand while fulfilling new requirements is a large LP solution space. Increasing market options, substrate availability, and digestion system capacity achieve this on the operator’s side. Policy makers could reduce normative requirements such as the maize cap or double counting of advanced fuels and favor high but uniform GHG requirements. Operators can prepare robustly for the future substrate mixture by adding digester volume and pre-treatment tech, ensuring long-term and diverse substrate availability, and contracts with flexible components. Although current market conditions can improve specific GHG emissions, they do not necessarily increase manure usage when other options, such as straw, are viable. Other regulatory support systems will be required to do so.

Improving the thermodynamic efficiency and turboexpander design in bottoming organic Rankine cycles: The impact of working fluid selection

In the contemporary context, significant importance is attributed to micro and small-scale Organic Rankine Cycle (ORC) units that are specifically designed for decentralized electricity generation. An essential component within each ORC system is the expander, available in both volumetric and turboexpander configurations. In the existing biogas plant with an Internal Combustion Engine (ICE), the ORC, functioning as a bottoming cycle (BORC) on ICE waste heat, is installed. The BORC utilizes the heat from exhaust gases and the cooling water of the ICE. The paper investigates the effects of various working fluids on both the thermodynamic efficiency of the BORC and the isentropic efficiency of the turboexpander, thus influencing the design parameters of the turboexpander (e.g., number of stages, stator and rotor blade heights, etc.). The BORC, employing the working fluid R141b, has exhibited superior thermodynamic performance, demonstrating a commendable 63.5 kW in net power with a thermodynamic efficiency of 13 %, and ultimately increased the power of the ICE (537 kW) by approx. 12 %. Regarding the turbine component, the turbine operating with the R141b working fluid demonstrated the highest power output and isentropic efficiency, achieving values of 64.14 kW and 67.4 %, respectively. A design was developed for the same turbine, with aerodynamically perfect profiles specially designed for the stator and rotor blades.

Improvement of substrate turnover through integrating dark fermentation into existing biogas plants

Improvement of substrate turnover through integrating dark fermentation into existing biogas plants

Centralized or decentralized? How to exploit Sweden’s agricultural biomethane potential

The agricultural sector holds great potential for contributing to European biomethane production, but how to best exploit it is still not clear. This study compares three technical solutions for producing liquefied biomethane from manure in Sweden: centralized biogas production and liquefaction, decentralized biogas production and centralized liquefaction, and decentralized biogas production and liquefaction. Technical and practical aspects of the three configurations are assessed through interviews with professionals, and the economic performance is compared through life cycle cost analysis. Depending on the conditions, the most cost-efficient alternative is either a gas pipeline from decentralized biogas production to a centralized liquefaction, or fully centralized production. The economic benefit of centralization increases with the number of farms involved but decreases with the biogas capacity of the system and the transport distance. The pipeline solution provides simple logistics and operation, although concession for pipe laying can be challenging. Moreover, a partly or fully centralized setup improves the delivery security of the system and reduces downtime. However, decentralized biomethane production can be an option for remote farms where centralization is not possible. For existing biogas plants, small-scale liquefaction or a pipeline to centralized liquefaction can be options for developing more biomethane production.

Integrating microalgae growth in biomethane plants: Process design, modelling, and cost evaluation

The integration of microalgae cultivation in anaerobic digestion (AD) plants can take advantage of relevant nutrients (ammonium and ortho-phosphate) and CO2 loads. The proposed scheme of microalgae integration in existing biogas plants aims at producing approximately 250 t·y−1 of microalgal biomass, targeting the biostimulants market that is currently under rapid expansion. A full-scale biorefinery was designed to treat 50 kt·y−1 of raw liquid digestate from AD and 0.45 kt·y−1 of CO2 from biogas upgrading, and 0.40 kt·y−1 of sugar-rich solid by-products from a local confectionery industry. An innovative three-stage cultivation process was designed, modelled, and verified, including: i) microalgae inoculation in tubular PBRs to select the desired algal strains, ii) microalgae cultivation in raceway ponds under greenhouses, and iii) heterotrophic microalgae cultivation in fermenters. A detailed economic assessment of the proposed biorefinery allowed to compute a biomass production cost of 2.8 ± 0.3 €·kg DW−1, that is compatible with current downstream process costs to produce biostimulants, suggesting that the proposed nutrient recovery route is feasible from the technical and economic perspective. Based on the case study analysis, a discussion of process, bioproducts and policy barriers that currently hinder the development of microalgae-based biorefineries is presented.

Perception of biogas plants: A public awareness and preference - A case study for the agricultural landscape

The energy transition and the EU's ambitious policies require member countries to find socially acceptable solutions. One possible solution is agricultural biogas plants. However, research on public acceptance of biogas plants has been a small part of the research on renewable energy sources. The aims of the article were to (I) examine the public awareness of agricultural biogas plants, (II) analyze the public opinion on the perception of biogas plants in a diverse landscape, and (III) perform visual assessment of the landscape with an existing biogas plant based on investments from Poland. A combination of methodological approaches was used to achieve the aims: survey research and visual assessment. Survey research was used to investigate the public awareness and perception of biogas plants in a diverse landscape. Visual assessment of operating biogas plant in the rural landscape was performed using the JAR-WAK landscape evaluation method. The conducted research showed that, according to the respondents, the biggest disadvantage of biogas plants is odors, and the greatest benefit is the production of energy and heat. The surveyed people also negatively perceived landscapes with biogas plants. However, the visual assessment for operating a biogas plant indicated no negative impact on the landscape.

Effect of Reactive and Non-Reactive Additive Treatment on the Recovery of Phosphorus from Biogas Digestate

The annual phosphate (PO43−) utilization has increased, leading to a depletion of existing sources of phosphorus (P). To overcome this, digestate as a source to recover P is being investigated. Due to the abundance of nutrients, the digestate from an agricultural biogas plant is used as fertilizer for crops. The separation of solids and liquids from the digestate by a screw press is the simplest form of concentrating, therefore, recovering PO43−. This is the most commonly employed method in existing biogas plants. However, the separation is not very efficient as only 20–30% of P is recovered in the solid phase. The goal of this study is to increase the separation efficiency and recover more P into the solid phase, in order to improve the transportability. For this, separation trials at a laboratory scale were performed for five experimental groups, with biochar and straw flour as non-reactive additives and kieserite as a reactive additive. In addition, untreated digestate was studied as a control. The control and the treatment with biochar and straw flour were carried out at 25 °C, while the treatment with kieserite was performed at 25 °C and 50 °C. The separation trails were performed at treatment times of 0 h, 1 h, 2 h, 8 h, and 20 h. The results showed that the treatment with additives had a beneficial effect on the recovery of P. It was noted that kieserite treatment at 25 °C and 50 °C bound about 61% of the total P present in the digestate to the solid phase. A sequential extraction was performed to study the effect of additives on the recovery of different P species. The results concluded that, compared to biochar and straw flour, kieserite was efficient in recovering the non-labile fractions (NaOH-P and HCl-P) of P, which act as slow-release fertilizers. This study shows that the use of additives, especially kieserite, has a positive influence on recovering P from digestate, and further research to optimize the recovery process would be beneficial.

Direct Methanation and Storage Concepts for the Flexibilization of Biogas Plants

AbstractEnrichment of the methane fraction in a biogas mixture is an innovative possibility to make existing biogas plants more flexible by using excess power. In the described concept, the CO2 in the biogas is directly catalytically converted into CH4 with H2. The CH4‐enriched biogas is again fed into the digester to save energy for later use in the combined heat‐and‐power unit. Additionally, the fed heat gas can mix and heat the substrate. A heat pipe injector system was therefore developed for cooling the hot biogas stream after methanation and to prevent damage to the microbial consortia during the biomass mixing. The concept was proven at a laboratory‐scale biogas plant.

Economic assessment for vegetable waste valorization through the biogas-biomethane chain in Italy with a circular economy approach

The current geo-political framework and the environmental concern about pollution and global warming are leading Europe to rethink its energy production, moving forward to the incentivization the renewable energy market. In this scenario, the use of waste from the agri-food sector shows a huge potentiality to enhance the transition in line with the circular economy principles. Biogas production represents an environmental friendly strategy to successfully recover large amounts of waste and by-products to produce renewable energy. Furthermore, in light of the rising need of green biofuels, biogas can be converted into biomethane, allowing the implementation of a full circular model. The objective of this paper is to perform an economic assessment to evaluate whether the upgrading of an existing biogas plant, in which the diet includes also vegetable waste from a plant producing frozen vegetables, could be profitable considering different scenarios, to reach a sustainable circular model. The analysis will be conducted through the Discounted Cash Flow method, considering four main indexes: NPV, DPBT, IRR, and PI. The results highlight the unprofitability of the biogas-biomethane chain if the upgrading system is performed maintaining the same characteristics of the starting plant. On the other hand, if changes in the digester's diet occur, the investment becomes immediately profitable in the considered time-span. The circular economy model is not completely accomplished, as profitability can only be reached if silage maize is partially kept as feedstock. Moreover, the conversion of the plant is not economically feasible if an adequate subsidy is not provided. The economic assessment of the upgrading system for biogas to biomethane is an essential element to be provided to the agribusiness entrepreneurs, as they need all the relevant economic aspects to decide to invest and adopt this solution to establish an innovative circular business model in agriculture.

Demand-oriented biogas production to cover residual load of an electricity self-sufficient community using a simple kinetic model

Flexible biogas production can enable demand-oriented energy supply without the need for expensive gas storage expansions, but poses challenges to the stability of the anaerobic digestion (AD) process. In this work, biogas production of laboratory-scale AD of maize silage and sugar beets was optimized to cover the residual load of an electricity self-sufficient community using a simple process model based on first-order kinetics. Experiments show a good agreement between biogas demand, predicted, and measured biogas production. By optimizing biogas conversion schedules based on the measured gas production, a gas storage capacity of 7–8 h was identified for maximum flexibility, which corresponds to typical gas storage sizes at industrial biogas plants in Germany. Various stability indicators were continuously monitored and proved resilient process conditions. These results demonstrate that demand-oriented biogas production using model predictive control is a promising approach to enable existing biogas plants to provide balancing energy.

Study of Methane Fermentation of Cattle Manure in the Mesophilic Regime with the Addition of Crude Glycerine

The urgency of the study is due to the need to increase the productivity of biogas plants by intensifying the process of methane fermentation of cattle manure in mesophilic mode by adding to it the waste from biodiesel production: crude glycerine. To substantiate the rational amount of crude glycerine in the substrate, the following tasks were performed: determination of dry matter, dry organic matter, and moisture of the substrate from cattle manure with the addition of crude glycerine; conducting experimental studies on biogas yield during fermentation of cattle manure with the addition of crude glycerine with periodic loading of the substrate; and development of a biogas yield model and determination of the rational composition of crude glycerine with its gradual loading into biogas plants with cattle manure. The article presents the results of research on fermentation of substrates in a laboratory biogas plant with a useful volume of 30 L, which fermented different proportions of crude glycerine with cattle manure at a temperature of 30 °C, 35 °C, and 40 °C. The scientific novelty of the work is to determine the patterns of intensification of the process of methane fermentation of cattle manure with the addition of different portions of crude glycerine. A rapid increase in biogas yield is observed when the glycerol content is up to 0.75%. With the addition of more glycerine, the growth of biogas yield slows down. The digester of the biogas plant, where experimental studies were conducted on the fermentation of substrates based on cattle manure with the addition of co-substrates, is suitable for periodic loading of the substrate. As a rule, existing biogas plants use a gradual mode of loading the digester. Conducting experimental studies on biogas yield during fermentation of cattle manure with the addition of crude glycerine with periodic loading of the substrate makes it possible to build a mathematical model of biogas yield and determine the rational composition (up to 0.75%) of crude glycerine with its gradual loading in biogas plants. Adding 0.75% of crude glycerine to the substrate at a fermentation temperature of 30 °C allows to increase the biogas yield by 2.5 times and proportionally increase the production of heat and electricity. The practical application of this knowledge allows the design of an appropriate capacity of the biogas storage tank (gasholder).

Key wastes selection and prediction improvement for biogas production through hybrid machine learning methods

As history shows, a linear production process results in a waste of resources. Using renewable energy can not only reduce waste but also protect the earth's resources. However, due to the high input costs of biogas manufacturing and a lack of standard manufacturing procedures, there have been few predictive models generated using multiple algorithms to analyze key input wastes and to predict output in the field of biogas generation. The lack of key wastes analysis may result in reductions in both the optimization of production processes and the stability of production, eventually affecting the popularity of biogas generation. Therefore, this research proposes a hybrid machine learning method based on random forest (RF) and long short-term memory (LSTM) analysis for redefining the key factors and improving the prediction of biogas generation output. The analysis adopted input and production output data from an existing biogas plant. Regarding the predication for biogas production, the performance of the proposed hybrid model exhibits 20% more accuracy than its nearest competitor among traditional analytic models. Coupled with the assistance of a hybrid machine learning method, the identification of key factors can be improved, providing users with suggestions and guidance for modifying parameters. Through a precise control of final output and manufacturing process, this methodology may be expected to help reduce costs and accelerate the popularity of biogas.

Fish sludge as a co-substrate in the anaerobic digestion of municipal sewage sludge- maximizing the utilization of available organic resources

The thriving of on-land based aquaculture at Norway's western region is to provide higher amounts of discharges to handle sustainably. Utilizing the sludge generated as a co-digestion substrate at already existing biogas plants treating sewage sludge may contribute to higher yields and improved nutrient recirculation. For this study, both wet and dried fish sludge samples were tested as co-substrates on the digestion of sewage sludge in semi-continuous bench-scale reactors. Additions of 30% in volatile solids (VS) of fish sludge gave a 35% methane production increase at mesophilic conditions. In thermophilic conditions the same addition caused process inhibition due to high ammonia levels obtained. Addition of up to 20% VS of dried fish sludge provided an increase between 30–50% in the yield. Fish sludge was verified as a promising co-substrate to increase the yield. However, heavy metals accumulation during the process caused the downgrading of the digested biomass as soil conditioner.

Biogas plant in Chittorgarh district of Rajasthan: A case study

The study focused on evaluating the performance of biogas plant among the Chittorgarh district of Rajasthan state. Data from existing biogas plant located in Chittorgarh District was used for the study. Survey of 32 randomly selected biogas plant was completed. Only Deenbandhhu biogas plants were identified. 27 biogas plants were found operational and 5 biogas plants were found nonoperational. Lack of dung availability and water was main reason for nonfunctional biogas plant. Farmers are practiced to collect bio-slurry in a pit and used it as organic manure twice in a year.

Feasibility of biogas plant in Sikar district Rajasthan

A study was conducted to evaluate performance of biogas plant in Sikar district of Rajasthan (India). Existing biogas plant constructed and commissioned to Biogas Development and Training Center, Udaipur in District Sikar were considered for the study. Out of total 1383 biogas plant constructed in District Sikar 60 biogas plants were selected on random basis. A questionnaire was prepared for the study. Out of selected 60 biogas plants, 54 plants were found operational or 6 plants were found non-operational due to migration of cattle. The bio-slurry is collected in a pit and used as manure once or twice in a year. Mostly Deenbandhu type biogas plants are installed.

Biogas Plants as Hydrogen Production Facilities and Greenhouse Gas Sinks: Technology Comparison, Challenges and Potentials for Carbon Negative Hydrogen Production (HyBECCS)

The biological transformation of industrial value creation aims to provide solutions with regard to the ecological challenges of our time. Concerning climate change, the most critical transformation area is the energy sector. Alternatives to fossil energy supply as well as the active removal of carbon dioxide (CO2) from the atmosphere are considered the most important challenges that technology must provide solutions for. A promising approach in this context is the carbon-negative hydrogen production from biogenic sources (HyBECCS). This approach can be implemented on the basis of existing biogas plants. Technology alternatives for retrofitting these plants to HyBECCS facilities are elaborated and their respective strengths, weaknesses, opportunities and threats are derived in this paper. Further, taking the example of Baden-Wuerttemberg in Germany, the ecologic potentials concerning hydrogen (H2) production and greenhouse gas (GHG) reduction are estimated. The current total H2 demand of 1.8 TWh/a in this area could be fully covered if 1/7 to 1/4 of existing biogas plants were retrofitted for H2 production. The substitution of gray H2 can avoid GHG emissions of 2.2-3.7 million t CO2 per year. In addition, capture and storage or long-term use of the resulting biogenic CO2 can enable negative emissions of 2.5-6 million t CO2 per year.

Extending the Operation of Existing Biogas Plants: Which Follow-Up Concepts and Plants Will Prevail?

For the existing biogas plants (BGP) in Germany, the period of the public support scheme begins to end in 2021. From a technical point of view, essential components have an operational life span of more than 20 years and allow for an extended operation. However, a profitable extension would require suitable follow-up concepts and depends on the underlying plant-specific setup, the regional conditions, as well as the regulatory and economic framework. Based on an expert evaluation, four promising follow-up concepts were identified in a multistage process consisting of expert interviews, workshops, and an online survey. These follow-up concepts are “Basic flexibilization,” “Substrate change,” “Seasonal flexibilization,” and “Biomethane upgrading.” They were assessed with a plant-specific biogas repowering model for a heterogeneous data set of 2,508 BGPs and were compared in three scenario frameworks to derive robust development paths. To capture the heterogeneity of the existing BGPs in Germany, the model was developed further regarding regional parameters such as power output, substrate mix, and emission factors. Across all the scenarios, “Seasonal flexibilization” proves to be the most promising follow-up concept for more than 50% of the BGPs. This is followed by “Substrate change,” which is particularly suitable for larger BGPs with high shares of energy crops and no heat utilization. Biomethane upgrading is usually the second choice compared to participation in extended public support schemes for electricity production. However, it is the only concept that is profitable under current market conditions due to the high CO2-quota prices in the German fuel sector. The development pathways also show a significant potential to increase the net GHG reduction, which on BPG average can be nearly doubled. Our approach shows that the interplay of the heterogeneous BGP structure, the applied economic decision variable, and the nonuniform framework conditions in different energy markets is of crucial importance when assessing similar biogas markets, identifying robust follow-up pathways, or designing framework policies.

Geospatial Analysis and Environmental Impact Assessment of a Holistic and Interdisciplinary Approach to the Biogas Sector

Crop-based biogas energy production, in combination with electricity generation under subsidy schemes, is no longer considered a favourable business model for biogas plants. Switching to low-cost or gate fee feedstocks and utilising biogas via alternative pathways could contribute to making existing plants fit for future operations and could open up new space for further expansion of the biogas sector. The aim of this study was to combine a holistic and interdisciplinary approach for both the biogas production side and the utilisation side to evaluate the impact of integrating the biogas sector with waste management systems and energy systems operating with a high share of renewable energy sources. The geospatial availability of residue materials from agriculture, industry and municipalities was assessed using QGIS software for the case of Northern Croatia with the goal of replacing maize silage in the operation of existing biogas plants. Furthermore, the analysis included positioning new biogas plants, which would produce renewable gas. The overall approach was evaluated through life cycle assessment using SimaPro software to quantify the environmental benefits and identify the bottlenecks of the implemented actions. The results showed that the given feedstocks could replace 212 GWh of biogas from maize silage in the relevant region and create an additional 191 GWh of biomethane in new plants. The LCA revealed that the proposed measures would contribute to the decarbonisation of natural gas by creating environmental benefits that are 36 times greater compared to a business-as-usual concept. The presented approach could be of interest to stakeholders in the biogas sector anywhere in the world to encourage further integration of biogas technologies into energy and environmental transitions.

Energy use of biogas generated in a sewage treatment plant: potential to reduce eletricity costs and atmospheric emissions in northeast Brazil

This research aimed to evaluate the management of a Sewage Treatment Plant (STP) and the existing biogas plant. A mathematical model was used to analyze the behavior of methane, biogas production and energy generation potential for a period of three years at the Jacuípe II Treatment Plant, located in northeastern Brazil. If the biogas plant were in operation, it would be possible to obtain autonomy for energy generation in the years 2016 and 2018. Greenhouse Gas Inventories - GHG, situational diagnosis of the biogas plant and scenario of financial losses with the deactivation of the plant were prepared. The results revealed that the emission of 1,958.38 tCH4 could have been avoided with the use of an energy generator (85% less than that emitted) or 1,151.99 tCH4 (50% less than emitted), if combustion by burner/flare. In addition, the financial loss due to the inactivity of the biogas plant resulted in US$ 154,162.38, about 67% of the actual energy expenditure of the plant in the period from 2016 to 2018. The reactivation of the biogas plant present in this station will bring environmental benefits, since the emission of GHG will be mitigated, in addition to financial benefits, since the energy use of biogas in the plant will provide a reduction in the expenses with electricity from STP Jacuípe II, in line with the aspects of sustainability.

Characterisation of Wastewater and Treatment Efficiency of Biogas Plants: Effluent Discharge Quality

Aims: To characterise wastewater, assess effluent quality and treatment efficiency of 3 existing biogas plants in 3 distinct institutions in Ghana and to provide relevant data necessary to policy makers to inform decision and influence policy.
 Study Design: Laboratory analyses were conducted on wastewater samples from the University of Cape Coast (UCC), Mfantsipim Senior High School (Mfantsipim) and Ankaful Maximum Security Prisons (Ankaful), between January and April 2018.
 Methodology: In all, 192 wastewater samples were collected from UCC, Mfantsipim and Ankaful for analyses. Physical, chemical and biological parameters were analysed on raw wastewater and on the effluent. Quality parameters were determined using the protocol outlined in the Standard Methods.
 Results: The results showed significant differences between effluent quality from UCC, Mfantsipim and Ankaful with most of the quality parameters falling within the Ghana Environmental Protection Agency (EPA) guidelines. However, electrical conductivity (EC), total suspended solids (TSS), total dissolved solids (TDS), dissolved oxygen (DO), biological oxygen demand (BOD5), chemical oxygen demand (COD), ammonia-nitrogen (NH3-N), total coliforms (T. coli), Escherichia coli (E. coli) and Salmonella spp. (salmonella) exceeded the guideline values. The ratio between BOD5/COD was 0.5 and 0.3 for UCC and Ankaful respectively, indicating high biodegradability while Mfantsipim recorded 0.06, indicating low biodegradability. The parameters which had high treatment efficiency for the biogas plants was UCC (TSS 72.22%, total volatile solids (TVS) 78.41%, BOD5 64.22%, COD 63.56%, PO4 61.29%, T. coli 1.9 log reduction, E. coli less than 1 log reduction, salmonella 1.5 log reduction and vibrio cholerae (V. cholerae) 1 log reduction) followed by Mfantsipim (BOD5 70.45%, COD 83.84%, NO3 79.17%, T. coli 1.6 log reduction, E. coli 5 log reduction, salmonella 1.8 log reduction and V. cholerae complete removal), while Ankaful was (TDS 57.7%, TSS 68.17%, TVS 56.33%, BOD5 82.4%, COD 81.13%, T. coli less than 1 log reduction, E. coli less than 1 log reduction, salmonella less than 1 log reduction and V. cholerae 0.96 log reduction). The rest of the parameters exhibited negative and/or low values. The performance analysis of the three biogas plants showed that UCC performs a little better than Ankaful and far better than Mfantsipim in term of treatment efficiency.
 Conclusion: The performance analysis indicated that the biogas plants were under-performing which could be attributed to poor maintenance, design deficiencies, poor environmental conditions and voluminous in-put loads. These factors impact the treatment efficiency resulting in relatively poor effluent quality which could put the health of the public at great risk.
 It is therefore recommended that authorities and policy makers formulate appropriate regulations aimed at addressing the potential impact of poor effluent quality discharged into the environment.