Natural Wastewater Treatment Systems Research Articles

Enhancing pharmaceutical removal in a full-scale constructed wetland with effluent recirculation

Emerging organic micropollutants pose a threat to aquatic environments even at trace levels. Among the many different groups of emerging pollutants, pharmaceutical residues are of special concern because of their toxicity and long-term effects on biota. Natural wastewater treatment systems are effective at eliminating pharmaceuticals, but removals are usually incomplete. In this regard, effluent recirculation can help to improve the removal of pharmaceuticals in natural wastewater treatment systems with the goal of producing a better-quality effluent for reuse. This is particularly interesting for water-scarce regions such as semi-arid islands of this study. The obtained results provide evidence that effluent recirculation can significantly improve the removal of pharmaceuticals in natural wastewater treatment systems. Of the 11 compounds studied, the highest concentrations and detection frequencies (in decreasing order) were those of caffeine, paraxanthine, nicotine, ibuprofen, naproxen and atenolol. The average removals increased from 87.5% (no recirculation) to 97% (100% recirculation ratio), and these results are associated with an improved ammonium and total N removal with 100% recirculation. To the knowledge of the authors, this is the first study showing the positive effect of effluent recirculation on the removal of pharmaceuticals in a full-scale natural wastewater treatment system.

Feasibility of natural wastewater treatment systems and life cycle assessment (LCA) for aquatic systems

Background: Natural wastewater treatment systems (NWTSs) in small villages are a major challenge for European water authorities. With growing social demands for environmental practices, evaluating the feasibility and environmental impact of low-cost treatment systems for small residential areas is essential. Methods: To address this challenge, this study was conducted to evaluate 10 NWTSs seasonally in rural areas of Bursa, Turkey. Authorities over the facilities permitted the examination of workable, low-cost effluent management options. Also, using Open-LCA software based on ReCiPe MidPoint (H) version 1.67, these plants’ effects on global warming, Phosphorus-depletion, human toxicity, marine eutrophication, and freshwater eutrophication were examined. Results: According to the LCA findings, Deydinler NWTS had a greater impact across all three effect areas (freshwater eutrophication, marine eutrophication, and human toxicity), ranging from 11 to 41%. Pinar and Yenice facilities, however, had 26% and 27% larger impacts in the same two impacts (marine eutrophication and human toxicity). These systems performed on average at 67%, 50%, and 58% chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) elimination, respectively. Conclusion: According to the findings, 10 NWTSs have a treatment efficiency of about 70%. NWTSs are possibilities for decentralized wastewater treatment in small residential areas that are both cost-effective and environmentally favorable. By treating organic pollution naturally, without chemicals, and with minimal energy use, they lessen their negative environmental effects. The main findings of this study will be useful for academics in determining future research areas and identifying whom they might consult to help design carbon footprint of NWTS and future carbon reduction objectives.

E-Learning Proposal for 3D Modeling and Numerical Simulation with FreeFem++ for the Study of the Discontinuous Dynamics of Biological and Anaerobic Digesters

This work presents an original 3D code in FreeFem++ to recreate the behavior of anaerobic microorganisms in non-stirred anaerobic reactors with an intermittent feed. The physical and biochemical phenomena have been considered using a mathematical model based on a set of partial differential equations: Stokes, advection–diffusion, and diffusion–reaction. The description of the anaerobic metabolism was carried out by implementing the structured AMD1 model. The Galerkin finite element method has been used to solve the partial differential equations defined in the model. Finally, the methodology and procedures are presented by means of a concrete example. Thanks to the inclusion of this e-learning tool for use in virtual laboratories, it is possible to improve the understanding of engineering students on the functioning of the metabolism that takes place inside non-stirred anaerobic reactors that are fed discontinuously. This proposal reinforces to students, in a transversal way, both environmental sensitivity and awareness of the circular economy focused on the implementation of natural wastewater treatment systems in rural areas.

The Effect of Effluent Recirculation in a Full-Scale Constructed Wetland System

This study deals with the effect of effluent recirculation (ER) on the pollutant removal efficacy of a full-scale, hybrid treatment system composed of a macrophyte pond and a horizontal flow constructed wetland. The average removals of 5-day biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), turbidity, total N (TN), ammonium nitrogen (NH4-N), total phosphorus (TP), sulfates, E. coli and Total coliforms (TC) for the years 2017–2018 (no recirculation), 2019 (50% recirculation) and 2021 (100% recirculation) were compared. Results show a general improvement of the effluent with ER. Removals for 0%, 50% and 100% ER, respectively, were: 59%, 61% and 66% for COD; 90%, 96% and 96% for BOD; 94%, 94% and 99% for TSS; 33%, 40% and 67% for TN; 22%, 30% and 55% for NH4-N; 92%, 98% and 96% for sulfates; 99.6%, 99.7% and 99.9% for E. coli; and 99.5%, 99.7% and 9.9% for TC. No clear effect was observed on the removal of TP and dissolved PO4-P, which were very low. 50% ER improved turbidity removal from 88% to 91%, but 100% ER provided worse results. The removal of NH4-N and TN significantly improved with 100% ER. This indicates that ER can be a simple, economic, and feasible way to upgrade the performance of full-scale natural wastewater treatment systems.

Endogenous mechanism of microbial functional gene and exogenous nitrogen removal factors driven by sustainable iron-nitrogen cycling

Feammox and nitrate-dependent Fe(II) oxidation (NDFO) play an important role in the iron-nitrogen cycle, respectively. To further understand the intrinsic molecular biological mechanism of Feammox with NDFO and improve the total nitrogen (TN) removal efficiency of the culture system, functional gene endogenous development and exogenous factors affecting nitrogen removal driven by the iron-nitrogen cycle were analyzed. Principal component analysis (PCA) showed that the three different ecological groups all formed a similar stable iron-nitrogen bacteria community structure. For 16S rRNA and qPCR, the dominant bacterial genera of Feammox coupled with NDFO were closely related, the amount of nxrB, nirS, and nosZ gene are 1-2 orders of magnitude larger than the amoA, narG, and AMX gene, which are the most important endogenous factors affecting nitrogen removal in the system. And an interesting result is that amoA, nxrB, narG, nirS and nosZ genes were all significantly positively correlated with each other (p < 0.05), indicating that the nitrogen cycle function genes changed synchronously, which was consistent with the changes in the microbial genera. The experimental process was optimized by changing environmental factors such as pH, organic carbon and extracellular electron shuttle to improve nitrogen removal. The results indicated that TN removal efficiency (67.05–76.12%) was greatly increased compared with the previous experiments (18.62–19.38%), which was the highest in pH = 8 groups (COD/TN = 3) because pH of the enrichment system stabilized to approximately 8. Moreover, the added 9,10-anthraquinone-2,6-disulfonate (AQDS) has improved TN removal efficiency to 67.27–87.75% through its extracellular electron transfer function, which was higher than that of control groups (without AQDS). This study provides a new scientific perspective and sustainable practical support for nitrogen pollution removal in the natural ecosystems or wastewater treatment systems.

Climate Change Mitigation Tool Implemented through an Integrated and Resilient System to Measure and Monitor Operating Variables, Applied to Natural Wastewater Treatment Systems (NTSW) in Livestock Farms

In this study, the main elements that can make up a Natural Treatment System for Wastewater (NTSW), its most important parameters and properties of operation and design, have been analyzed, as well as the environmental problems derived from the generation of large amounts of slurry. The objective of this paper is to propose a methodology to improve the operation of these systems, associated with small and medium-sized livestock farms, in insular and isolated systems such as the Canary Islands. An Integrated and Resilient System (IRS) for monitoring and measuring operational variables quasi-continuous and in situ is proposed. Low-cost technology and open source hardware are employed, as well as application of the IoT (Internet of Things) strategies to share and analyze the information collected in the cloud. In view of the high degree of resilience and the simplicity of this type of technology, as well as its low cost, it is concluded that it is feasible to create a measurement system with these characteristics that can be used for NTSW parameterization, and other purposes. Satisfactory results were obtained for several parameters (ambient temperature, relative humidity, UV radiation, atmospheric pressure). It is presented as a novel proposal based mainly on low-cost technology and free software with which to improve the NTSW operation process.

Investigating public awareness towards wastewater management in a small community

&lt;p&gt;A critical element for the successful management of wastewater is the active participation of residents in all stages of treatment in order to ensure public acceptance. The primary purpose of this study is to identify and analyze the specific views and attitudes of the inhabitants of Leros Island, Greece, regarding (a) the performance of the wastewater treatment plant (WWTP) operating on Leros Island and (b) their level of awareness on and (c) their willingness to accept a natural wastewater treatment system. This study also emphasizes the significance of a participatory approach to construct sustainable wastewater treatment systems in small communities. Results show an apparent lack of information regarding natural wastewater treatment systems for all respondents, and it turns out that a high level of education does not necessarily mean higher awareness of alternative wastewater treatment methods nor greater acceptance of innovative wastewater treatment systems. Age showed a significant correlation with social acceptance of alternative ways of waste treatment, with people over the age of 56 shown to be most willing to apply a natural wastewater treatment system in remote areas of the Leros island. Environmental awareness policies could contribute to more sustainable community wastewater management.&lt;/p&gt;&#x0D;

Investigating the working efficiency of natural wastewater treatment systems: A step towards sustainable systems

Abstract Globally, wastewater is a vital resource and requires appropriate treatment management strategies. Wastewater has become a major source of irrigation in the peri-urban areas of developing nations. With the increasing amount of wastewater generation, there are several complications in using treatment systems in terms of installation, operation and maintenance, and size in developing countries. Recently, natural treatment systems are gaining popularity due to less cost and maintenance and have been preferred in peri-urban settings. In this study, the working efficiency of the natural systems was assessed from case studies from Vizianagaram, Andhra Pradesh, India. The nutrient (Phosphorous and Nitrogen content) and organic matter removal efficiency of four natural treatment systems (NTS) having different operation, maintenance and loading rates were investigated. The study showed that natural treatment systems have good potential for peri-urban wastewater treatment. It was also observed that waste-stabilization based systems perform better than those based on duckweed and hyacinth plants. Regularly maintained and operated systems show removal efficiency on the order of 80% for organic and nutrients and performed better than others. The study indicates that decentralized, adequately maintained Waste Stabilization Ponds (WSP) offer a viable, self-sustaining and eco-friendly alternative for wastewater treatment to supply irrigation water in rural areas.

A Framework Based on Finite Element Method (FEM) for Modelling and Assessing the Affection of the Local Thermal Weather Factors on the Performance of Anaerobic Lagoons for the Natural Treatment of Swine Wastewater

Anaerobic lagoons are natural wastewater treatment systems suitable for swine farms in small communities due to its low operational and building costs, as well as for the environmental sustainability that these technologies enable. The local weather is one of the factors which greatly influences the efficiency of the organic matter degradation within anaerobic lagoons, since microbial growth is closely related to temperature. In this manuscript, we propose a mathematical model which involves the two-dimensional Stokes, advection–diffusion-reaction and heat transfer equations for an unstirred fluid flow. Furthermore, the Anaerobic Digestion Model No1 (ADM1), developed by the International Water Association (IWA), has been implemented in the model. The partial differential equations resulting from the model, which involve a large number of state variables that change according to the position and the time, are solved through the use of the Finite Element Method. The results of the simulations indicated that the methodology is capable of predicting reasonably well the steady-state of the concentrations for all processes that take place in the anaerobic digestion and for each one of the variables considered; cells, organic matter, nutrients, etc. In view of the results, it can be concluded that the model has significant potential for the design and the study of anaerobic cells’ behaviour within free flow systems.

Enhancing nitrogen removal from anaerobically-digested swine wastewater through integration of Myriophyllum aquaticum and free nitrous acid-based technology in a constructed wetland.

Despite of low operation costs and convenient maintenance, the application of natural systems for swine wastewater treatment has been limited by large construction area and unsatisfactory effluent quality. Introducing ammonium high uptake aquatic plants and shifting nitrogen removal pathway from nitrate to nitrite in constructed wetlands (CWs) has been regarded as promising approach to promote their performances. This study aimed to establish nitrite pathway and enhance N removal via free nitrous acid (FNA)-sediment treatment and Myriophyllum aquaticum vegetation in the CWs treating anaerobically digested swine wastewater. Nitrite pathway was successfully and stably achieved in the M. aquaticum CW with FNA-treated sediment. The overall removal efficiencies of ammonium nitrogen and total nitrogen were 42.3±10.2% and 37.7±9.3% in the planted CWs with FNA-treated sediment, which were 76.3% and 65.4% higher than those in the conventional oxidation pond system, respectively. Microbial community analysis (qPCR and metagenomics) suggested that the nitrite pathway established through FNA-sediment treatment was based on the inactivation of nitrite oxidizing bacteria (lower nxrA gene abundance) and the reduction of relative abundances of NOB (especially Nitrobacter and Nitrospira). During the denitrification processes, the integration of M. aquaticum vegetation with FNA-sediment treatment can lower the nitrate reduction by decreasing narG gene abundances and decreasing the relative abundances of napA affiliated bacteria (especially Bradyrhizobium), while strengthening reduction of nitrite and nitrous oxide by increasing nirK and nosZ gene abundances and enriching the corresponding affiliated microbial taxa, Mycobacterium and Bacillus, respectively. Our findings suggest that applying FNA-based technology in CW systems is technically and economically feasible, which holds promise for upgrading current CW systems treating swine wastewater to meet future water quality requirements.

Hybrid treatment systems: a paradigm shift to achieve sustainable wastewater treatment and recycling in India

This study assesses a trade-off between mechanized treatment systems and natural treatment systems for wastewater treatment (WWT) and recycling approaches. Investigation on this trade-off is carried out using field data on operation and maintenance (O and M) costs and land requirements. It is then shown that none of them in solo are techno-economically viable and environmentally sustainable for WWT in urban areas in India. Hence, a paradigm shift in WWT in India is proposed to adopt hybrid treatment systems (HTSs) approach. HTSs involve treatment considering a combination of natural and mechanized treatment approaches. Adoption of HTSs will result in energy savings and environmental benefits and hence will help India to achieve various national and international commitments of WWT and recycling.

Occurrence, fate and removal of microplastics as heavy metal vector in natural wastewater treatment wetland system

Microplastics pollution in aquatic ecosystems is of great concern; however, systemic investigations are still lacking in freshwater wetland systems used for wastewater treatment. The present study discusses such freshwater wetland system in Eastern India to understand its microplastics transport mechanism, heavy metals association and microplastics removal efficiency. Microplastics (63 µm - 5 mm) were heavily found in surface water and sediments of treatment ponds (7.87 to 20.39 items/L and 2124.84 to 6886.76 items/kg) and associated wastewater canals (30.46 to 137.72 items/L and 1108.78 to 34612.87 items/kg). A high content of toxic metals (As, Cd, Cr, Cu, Ni, Pb and Zn) were found on the microplastics with polyethylene terephthalate and polyethylene as major plastics types which were also found in fishes and macroinvertebrates of treatment ponds. Machine learning algorithm revealed a close association between microplastics content in fishes and surface water, indicating risk associated with floating microplastics to the aquatic biota. The study also revealed that microplastics were acting as heavy metals vector and potentially causing fish contamination. Surface water microplastics removing efficiency of the treatment ponds was estimated to be 53%. The study bespeaks about transport of microplastics through wastewater canals and their retention in treatment ponds emphasizing sustainability maintenance of natural wastewater treatment systems especially considering microplastics contamination to the aquatic biota of freshwater wetland systems.

Nitrogen removal in an aerobic gravel filtration-sedimentation pond-constructed wetland-overland flow system treating polluted stream waters: Effects of operation parameters

Nitrogen pollution in streams can be controlled by serially constructing natural wastewater treatment (NWT) systems inside streams. Therefore, a pilot-scale hybrid NWT system consisting of gravel filtration (GF), sedimentation pond (SP), gravel filtration-free water surface constructed wetland (GF-FWSCW), and gravel filtration-overland flow (GF-OF) was installed in order to prevent contamination in a stream (Nigde stream) that feeds and pollutes surface water source (Akkaya lake). The pilot-scale system was installed on a new 60 m-long channel which was located off the stream. Changes in ammonium (NH4+-N), organic nitrogen (Norg.), total nitrogen (TN), and biochemical oxygen demand (BOD) concentrations was routinely monitored in influent and effluent of all stages of the hybrid NWT system and the bottom sediment of the SP over a one-year operation period. According to the study results, while NH4+-N plus Norg. was reduced by an average of 75% (from 49,1 mg L−1 to 7,1 mg L−1), TN was reduced by an average of 85% (from 50,2 mg L−1 to 12,4 mg L−1). Colder seasons and higher hydraulic loading rates (HLRs) negatively affected nitrogen removal efficiency of the pilot-system. The use of vegetation and filter medium had a positive effect on the average removal efficiencies. The results showed that nitrogen pollution in polluted streams could be greatly reduced by establishing a NWT system in series within them.

Towards sustainable wastewater management: A spatial multi-criteria framework to site the Land-FILTER system in a complex urban environment

Land is a pricy and scarce resource, particularly in urban areas. If it is utilized effectively, suitable sites can be allocated for urban wastewater safe disposal through effluents treatment and reuse. This study used multicriteria decision-making approach known as weighted linear combination to map the suitability of an on-site natural wastewater treatment system in the urban and industrial environments—selecting Faisalabad City in Pakistan as the study area. Location of the study region in a water-scarce zone increases the scope of the untreated wastewater disposal into land and water bodies as well as its reuse for irrigation. Data on climate parameters (i.e., temperature, rainfall, and evapotranspiration), geophysical parameters, (i.e., including soil, topography, depth to groundwater table, and groundwater electrical conductivity), and socioeconomic parameters (i.e., land cover maps and proximity from roads/railways and rivers/canals) are used for the development of weighted linear combination based suitability index maps. Analytical hierarchical process-based heuristic approach is adapted to estimate the relative importance of all the parameters. Weights with less than 0.10 consistency ratio are used in the preparation of the final suitability map. The land area required for the proposed on-site wastewater treatment system is estimated as a function of climatic factors and wastewater characteristics. Adoption of the proposed multicriteria framework helped identifying four potentially environment-friendly and economically viable sites. The results show that geospatial multicriteria framework could efficiently help urban planners in sustainable wastewater management, particularly in developing countries where climate-change-induced water scarcity and associated health issues are critical.

Pharmaceutical and personal care product residues in a macrophyte pond-constructed wetland treating wastewater from a university campus: Presence, removal and ecological risk assessment

Pharmaceuticals and personal care products (PPCPs) constitute a group of chemicals of concern because of their potential toxicity when reaching aquatic environments. Wastewaters are one of the main pathways of introduction into the environment of the chemical compounds used in PPCPs because, in most cases, wastewater treatment facilities are not 100% efficient in their removal. This problem is accentuated in rural zones and isolated communities where conventional treatment systems are too expensive to build and operate. Waste-stabilization ponds and constructed wetlands (CWs) are natural wastewater treatment systems which are used to improve the quality of sewage from small communities because of their low cost and easy maintenance. There is growing interest in combining the two technologies to make a more robust system, taking into account their respective strengths and weaknesses.In this work, a combined macrophyte pond-CW system was evaluated for the presence at three sampling points (influent, pond effluent and CW effluent) of fifteen steroid hormones and six benzotriazole ultraviolet stabilizers (BUVSs). None of the targeted BUVS compounds were detected in either the influent or effluent, probably because of the particular characteristics of the population served by the wastewater system. In contrast, eight different steroid hormone compounds were detected at concentrations ranging from 17.3 to 247.7 ng·L−1 in influent samples and from 8.1 to 22.1 ng·L−1 in final effluent samples. The pond-CW system showed high elimination rates of steroid hormone residues with average removal efficiencies of over 77%. This efficacy was confirmed in the ecological risk assessment evaluation that was performed. Final effluents showed a low ecological risk associated with steroid hormones in contrast to the medium-high ecological risks found in the influent samples.

Combined natural wastewater treatment systems for removal of organic matter and phosphorus from polluted streams

Natural wastewater treatment (NWT) systems may be a most suitable and economical solution method to ensure a cleaner environment and sustainable production in control of water pollution. Therefore, in this study, a NWT system was designed to reduce existing pollution in over-polluted Kızılca creek (Nigde, Turkey). The combined system consists of a settlement basin (SB), free water surface constructed wetland (FWS-CW) planted with Phragmites communis, and overland flow (OF) system planted with Italian ryegrass, respectively. The system was installed on the edge of the creek in 2014. Over-polluted creek water was treated by passing through the system, and the treated water was discharged into the creek. Total suspended solid (TSS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total phosphorus (TP) parameters were analyzed on samples taken from the inputs and outputs of all stages of the system. During an operating period of about 18 months, it was observed that the pollutant parameters were reduced to a great extent. Despite the high organic loading, it was determined that the treatment system could remove the TSS and the BOD up to 85%, and the TP up to 49%. Average removals were found to be higher in warm weather conditions where vegetation could grow best. Results suggest that the combined NWT systems can be used as a low-cost wastewater treatment alternative to improve the water quality of polluted streams in similar areas.

MS2 coliphage and E. coli UVB inactivation rates in optically clear water: dose, dose rate and temperature dependence.

Natural ultraviolet irradiance disinfection is known to play a significant role in both natural wastewater treatment systems and drinking water disinfection processes, while the influence of ultraviolet B (UVB) delivering method on sunlight disinfection outcome is still unclear. This study aims to determine the effects of environmentally relevant temperatures, UVB doses (J m-2) and dose rates (W m-2) on the inactivation and log reduction values (LRVs) of the F-RNA coliphage MS2 and Escherichia coli in optically clear water. E. coli and MS2 were separately incubated and irradiated at five different doses of UVB light that delivered using six UVB dose rates. The results of the study demonstrate that the UVB dose delivering method (combination of dose rate and exposure time) influences inactivation and LRVs of E. coli and MS2 at all UVB doses investigated (up to seven-fold difference). Two phases were identified within the UVB dose rate, UVB inactivation or LRV curves for both organisms; a UVB dose rate limited inactivation phase and a dose rate saturation inactivation phase. The results contribute to a better understanding of UVB disinfection in the environment and natural wastewater treatment systems, potentially improving the design and operation of high rate algal ponds.

A sample study on nitrogen removal from polluted streams by using hybrid natural wastewater treatment systems

&lt;p&gt;The ecological structure and function of the water reservoirs deteriorate dramatically because of streams fed by the excess nitrogen-containing wastewater. To protect the water reservoirs from polluted streams, structures such as natural wastewater treatment (NWT) systems to be created inside or outside streams may be a most suitable and economical solution method to overcoming the problem. In this study, a hybrid NWT system was installed to remove nitrogenous pollutants in Karasu creek (Nigde city, Turkey) in 2014. The system built near the creek consisted of feeding basin (FB), settlement basin (SB), free water surface-constructed wetland (FWS-CW), and overland flow (OF) system respectively. Despite quite high nitrogen loading rates, the system managed to reduce NH4+-N from average 29 mg/L to 12 mg/L and TN from 44 mg/L to 19 mg/L with an average removal efficiency of 57 %. Results revealed that hydraulic and nitrogen loading rate, temperature and seasonal variation, BOD/TKN ratio, hydraulic residence time (HRT), and the use of the filter material were effective on nitrogen removal. The results suggest that the hybrid NWT systems can be used as a low-cost wastewater treatment alternative to improve water quality in streams contaminated by nitrogenous pollutants in the similar areas.&lt;/p&gt;&#x0D;

Методические основы использования природнотехногенных систем для очистки сточных вод

Методические основы использования природнотехногенных систем для очистки сточных вод

Seasonal characteristics of surface water quality in the wastewater catchment system of an urbanizing basin

Vientiane, Lao PDR, has been subject to extensive and ongoing urbanization plans, including development of natural marshes and residentialization of paddy fields into suburban areas, despite natural marshes playing a vital role in treating wastewater from urban areas. Therefore, it is important to understand the current situation regarding the nutrient balance in these natural wastewater treatment systems to predict future conditions and design appropriate measures against water quality deterioration. However, limited data are available in Vientiane on the hydrological characteristics of water and nutrient runoff that flow into marshes through drainage canals. In this study, we conducted a periodic survey of drainage canals and Mak Hiao River in the wastewater catchment system surrounding Vientiane during the rainy and dry seasons. We monitored the discharge of surface water at 21 observation sites and analyzed water quality of nitrogen, phosphorus, and total organic carbon. These observations revealed that the concentrations of dissolved nitrogen and phosphorus were significantly higher at sites in urban areas, followed by sites in the main river basin and those in agricultural areas. Dissolved nitrogen and phosphorus concentrations varied with runoff discharge, especially in urban and river basin sites, with lower concentrations in the rainy season and higher concentrations in the dry season. On the other hand, we found no significant differences between the rainy and dry seasons in nutrient concentrations in the agricultural basin. Finally, we proposed measures to counteract the deterioration of water quality during dry seasons and simulated the impact of these measures.