Water quality evaluation system to assess the status and the suitability of the Citarum river water to different uses

Legacy sources determine current water quality: Nitrogen and phosphorus in streams of Australia, China, Sweden and USA

Waterborne nutrient loads to downstream ecosystems integrate contributions from both active and legacy sources. Effective mitigation of nutrient pollution and eutrophication around the world requires distinction of these, largely unknown, relative load contributions. Here, the active and legacy contributions to nitrogen and phosphorus loads are distinguished in numerous streams and associated hydrological catchments of Australia, China, Sweden, and USA. The legacy contributions overshadow the active ones in all countries during 2005-2020. China and USA, with higher population densities and related overall human-activity levels, also have substantial active contributions. The median values of legacy concentration contributions of total nitrogen range from 321 (in Sweden) to 1850 μg/L (in USA); whereas the active contributions range from 2.2 (in Australia) to 315 μg/L (in USA). In China, nitrogen data are available only for ammonia, with median concentration contributions of 294 μg/L for legacy and 352 μg/L for active sources. For total phosphorus, the median values of legacy concentration contributions range from 28.8 (in Sweden) to 270 μg/L (in USA), while the active ones range from 0.1 (in Australia) to 67.3 μg/L (in USA). For relatively fast mitigation responses, China and USA need to mitigate their current nutrient emissions, while Australia and Sweden need a shift in mitigation focus to targeting their dominant legacy source contributions. The data-driven method testing in this study supports the used source distinction-attribution approach. This enables consistent source identification and tailoring of targeted measures for effective nutrient load mitigation in various regional contexts.

Identification of pollution source and prediction of water quality based on deep learning techniques

Semi-arid rivers are particularly vulnerable and responsive to the impacts of industrial contamination. Prompt identification and projection of pollutant dynamics are crucial in the accidental pollution incidents, therefore required the timely informed and effective management strategies. In this study, we collected water quality monitoring data from a typical semi-arid river. By water quality inter-correlation mapping, we identified the regularity and abnormal fluctuations of pollutant discharges. Combining the association rule method (Apriori) and characterized pollutants of different industries, we tracked major industrial pollution sources in the Dahei River Basin. Meanwhile, we deployed the integrated multivariate long and short-term memory network (LSTM) to forecast principal contaminants. Our findings revealed that (1) biological oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen, total phosphorus, and ammonia nitrogen exhibited high inter-correlations in water quality mapping, with lead and cadmium also demonstrating a strong association; (2) The main point sources of contaminant were coking, metal mining, and smelting industries. The government should strengthen the regulation and control of these industries and prevent further pollution of the river; (3) We confirmed 4 key pollutants: COD, ammonia nitrogen, total nitrogen, and total phosphorus. Our study accurately predicted the future changes in this water quality index. The best results were obtained when the prediction period was 1 day. The prediction accuracies reached 85.85%, 47.15%, 85.66%, and 89.07%, respectively. In essence, this research developed effective water quality traceability and predictive analysis methods in semi-arid river basins. It provided an effective tool for water quality surveillance in semi-arid river basins and imparts a scientific scaffold for the environmental stewardship endeavors of pertinent authorities.

Evaluation of Darbandikhan Lake and its tributaries' water quality in the Sulaymaniyah Province in Iraqi Kurdistan, using the water quality index model and multivariate statistical analysis

This study evaluated the characteristics of the water in Darbandikhan Lake and its rivers in the Kurdistan Region of Iraq. For this purpose, 25 samples were collected seasonally and analysed for 36 physiochemical parameters. The proportions of physiochemical parameters exceeding the WHO standards in the samples with their highest exceedances were 9894% for Al, 198% for Mn, 40% for Pb, 1.6% for pH, 3250% for PO4, 11.8% for Sr, 155% for T.Alk, 7813% for turbidity, 1188% for Ti, 1033% for Tl and 1293% for V in the river water and 120% for Co, 74% for Cr, 4485% for Fe and 9% for K in the lake water. The pollution sources were designated by multivariate statistical analysis as being related to industrial and domestic waste, solid waste disposal, fertilisers and organic contamination from agricultural and natural sources. The water quality index (WQI) results were 22.3 to 721.3 for drinking, 13.9 to 86.2 for irrigation, 1.4 to 299.5 for livestock, 71.5 to 1754.4 for the textile industry, 20.7 to 237.9 for recreation and 64.6 to 1867.4 for aquatic life. The irrigation water quality index (IWQI) results were excellent for sodium adsorption ratio (SAR), and for the US salinity scale, all water samples fell into the medium salinity-low sodium category (C2-S1) in all seasons, except for all Chaqan River samples. The Tanjaro River sample in spring fell in the relatively high salinity-low sodium category (C3-S1), excellent and good for sodium percentage (Na%), suitable to moderate for permeability index (PI%), suitable to unsuitable for magnesium hazard percentage (MH%), suitable for Kelly Index (KI) and safe to unsuitable for residual sodium carbonates (RSC). The Sirwan River, Tanjaro River and Zmkan River took first to third place in both the annual average pollution share ratio and the discharge. While the Zalm River ranked fourth in discharge and fifth in pollution share ratio, the Chaqan River was the reverse. The highest pollution share ratio was 64.3 for the Sirwan River in summer, and the lowest was 0.7 for the Zalm River in autumn.

Prediction of long-term water quality using machine learning enhanced by Bayesian optimisation

Water quality assessment is critical to better recognise the importance of water in human society. In this study, a new framework to predict long-term water quality is proposed by using Bayesian-optimised machine learning methods and key pollution indicators collected from monitoring stations in the Pearl River Estuary, Guangdong, China. The optimised stacked generalisation (SG-op) model achieved the best performance with the highest accuracy (0.992) and Kappa coefficient (0.987). Feature importance of the prediction model was consistent with key pollution indicators. The Spearman rank correlation coefficient was used to determine the significance level of the variation trends of different pollution indicators. The results show that the total phosphorus (TOP), dissolved oxygen (DO), chemical oxygen demand (COD), and petroleum (PET) among the key pollution indicators were on an upward trend in the study area. This framework can be applied to efficiently predict future water quality and to provide technical support for emergency pollution control.

Water quality and trophic status of Lake Mariut in Egypt and its drainage water after 8-year diversion

Water resource management and lake rehabilitation are global interest, to overcome the acute water scarcity facing most urban areas, especially in developing countries. Lake Mariut (LM) is an Egyptian lake that lies south of the Mediterranean Sea, and its management had a great interest in Alexandria's future development and as a part of the environmental sustainability of the Mediterranean basin. LM consists of 4 major basins, namely, main (MB), northwest (NWB), southwest (SWB), and fishery (FB). The MB has deteriorated as it consistently received (sewage and industrial) wastewaters till 2010. This was the date of diversion of the polluting sources as a rehabilitation step. The present work is made after elapsing 8 years from the diversion and aims at monitoring and assessing the status of the water quality not only of MB but also for the other 3 basins too. This was carried out twice, one in cold winter and the other in warm summer. The parameters studied were physico-chemical including water temperature, pH, dissolved oxygen/hydrogen sulfide (DO/H₂S), salinity, and chlorophyll a besides nutrient salts (nitrogen, N and phosphorus, P compounds). The results revealed that the waters of both MB and SWB basins were depleted in DO to a level difficult to sustain fish life and showed elevated levels of most nutrient salts. Trophically, all the studied basins were in eutrophic-hypereutrophic condition. As a result of pollution source diversion away from MB to be discharged in the downstream part of Umum Drain (UD), the levels of TN and TP entering Mex Bay through UD were slightly higher than the permissible limit and lower than dangerous loading. The applying of principle component analysis (PCA)-based classification approach, for obtaining the WQI on the current study, revealed that the FB, NWB, and SWB₂₀₀₀ showed a relatively good water quality when compared with MB. The depletion in the vital DO is catastrophic and needs urgent solution/s. One of the proposed solutions is the dredging of bottom spoiled organic-rich sediments. This and other suggested solutions are, however, discussed, evaluated, and presented.

Environmental prioritization of pesticide in the Upper Citarum River Basin, Indonesia, using predicted and measured concentrations

A novel screening method was developed to prioritize aquatic and human health risks of pesticides based on usage data, runoff modelling and effect prediction. An important asset of this new method is that it does not require measured concentration data, which are often unavailable or difficult to obtain in low- and middle-income countries like Indonesia. The method was applied to prioritize 31 agricultural pesticides used in the Upper Citarum River Basin in West Java, Indonesia. Ranking of pesticides based on predicted concentrations generally showed good agreement with ranking based on concentrations measured by passive sampling. The individual pesticide intake through the consumption of river water was predicted to cause negligible human health risks, but substantial aquatic risks (i.e. PEC/PNEC >1) were predicted for profenofos (5.2.E+01), propineb (3.6.E+01), chlorpyrifos (2.6.E+01), carbofuran (1.7.E+01), imidacloprid (9.4.E+00), methomyl (7.6.E+00) and chlorantraniliprole (3.6.E+00). In order to protect the aquatic environment, water managers are advised to take measures to reduce the use and runoff of these pesticides in the UCRB. The screening assessment can be further refined by performing additional effect studies for some pesticides, pesticide mixtures and validation of the predicted water concentrations by targeted measurements.

Water quality trend assessment in Jakarta: A rapidly growing Asian megacity

Megacities are facing serious water pollution problems due to urbanization, rapid population growth and economic development. Water is an essential resource for human activities and socio-economic development and water quality in urban settings has important implications for human and environmental health. Urbanization and lack of sewerage has left the water in Jakarta, Indonesia in a heavily polluted condition. Rigorous assessment of urban water quality is necessary to understand the factors controlling water quality conditions. We use trend analysis to assess the current water quality conditions in Jakarta, focusing on Biochemical Oxygen Demand (BOD), Dissolved Oxygen (DO), and Total Suspended Solids (TSS). In most monitoring stations analyzed, BOD and TSS concentrations have decreased over time, but from large starting concentrations. DO in most monitoring stations has increased. Although Jakarta’s water quality has shown some improvement, it remains heavily impaired. The average value of BOD is low in upper stream stations compared to middle and lower stream stations. BOD and TSS trends of some water quality stations in middle and lower streams show increasing trends. Cluster analysis results suggest three groups for BOD and TSS, and four groups for DO. Understanding water quality conditions and factors that control water quality suggest strategies for improving water quality given current trends in climate, population growth and urban development. Results from this study suggest research directions and management strategies to address water quality challenges.

Agricultural reuse of municipal wastewater through an integral water reclamation management

The DESERT-prototype, a state-of-the-art compact combination of water treatment technologies based on filtration and solar-based renewable energy, was employed to reclaim water for agricultural irrigation. Water reclaimed through the DESERT-prototype (PW) from a secondary effluent of a wastewater treatment plant, as well as conventional irrigation water (CW) and the secondary effluent (SW) itself, were employed to cultivate baby romaine lettuces in a greenhouse in Murcia (Spain), by means of drip and sprinkler irrigation methods, thus establishing six treatments. Assessments of physicochemical and microbiological quality of irrigation water, as well as agronomic and microbiological quality of crops from all treatments, showed that results associated to PW complied in all cases with relevant standards and guidelines. In contrast, results linked to SW and CW presented certain non-compliance cases of water and crop microbiological quality. These assessments lead to conclude that the DESERT-prototype is an appropriate technology for safe water reclamation oriented to agricultural production, that can be complemented by a proper irrigation method in reaching safety targets.

Development of river water quality indices-a review

The use of water quality indices (WQIs) as a tool to evaluate the status of water quality in rivers has been introduced since the 1960s. The WQI transforms selected water quality parameters into a dimensionless number so that changes in river water quality at any particular location and time could be presented in a simple and easily understandable manner. Although many WQIs have been developed, there is no worldwide accepted method for implementing the steps used for developing a WQI. Thus, there is a continuing interest to develop accurate WQIs that suit a local or regional area. This paper aimed to provide significant contribution to the development of future river WQIs through a review of 30 existing WQIs based on the four steps needed to develop a WQI. These steps are the selection of parameters, the generation of sub-indices, the generation of parameter weights and the aggregation process to compute the final index value. From the 30 reviewed WQIs, 7 were identified as most important based on their wider use and they were discussed in detail. It was observed that a major factor that influences wider use of a WQI is the support provided by the government and authorities to implement a WQI as the main tool to evaluate the status of rivers. Since there is a lot of subjectivity and uncertainty involved in the steps for developing and applying a WQI, it is recommended that the opinion of local water quality experts is taken, especially in the first three steps (through techniques like Delphi method). It was also observed that uncertainty and sensitivity analysis was rarely undertaken to reduce uncertainty, and hence such an analysis is recommended for future studies.

Feasibility analysis of wastewater and solid waste systems for application in Indonesia

Indonesia is one of many developing countries with a backlog in achieving targets for the implementation of wastewater and solid waste collection, treatment and recovery systems. Therefore a technical and financial feasibility analysis of these systems was performed using Indonesia as an example. COD, BOD, nitrogen, phosphorus and pathogen removal efficiencies, energy requirements, sludge production, land use and resource recovery potential (phosphorus, energy, duckweed, compost, water) for on-site, community based and off-site wastewater systems were determined. Solid waste systems (conventional, centralized and decentralized resource recovery) were analyzed according to land requirement, compost and energy production and recovery of plastic and paper. In the financial analysis, investments, operational costs & benefits and Total Lifecycle Costs (TLC) of all investigated options were compared. Technical performance and TLC were used to guide system selection for implementation in different residential settings. An analysis was undertaken to determine the effect of price variations of recoverable resources and land prices on TLC. A 10-fold increase in land prices for land intensive wastewater systems resulted in a 5 times higher TLC, whereas a 4-fold increase in the recovered resource selling price resulted in maximum 1.3 times higher TLC. For solid waste, these impacts were reversed - land price and resource selling price variations resulted in a maximum difference in TLC of 1.8 and 4 respectively. Technical and financial performance analysis can support decision makers in system selection and anticipate the impact of price variations on long-term operation. The technical analysis was based on published results of international research and the approach can be applied for other tropical, developing countries. All costs were converted to per capita unit costs and can be updated to assess other countries' estimated costs and benefits. Consequently, the approach can be used to guide wastewater and solid waste system planning in developing countries.

Assessment of water quality parameters using multivariate analysis for Klang River basin, Malaysia

This case study uses several univariate and multivariate statistical techniques to evaluate and interpret a water quality data set obtained from the Klang River basin located within the state of Selangor and the Federal Territory of Kuala Lumpur, Malaysia. The river drains an area of 1,288 km(2), from the steep mountain rainforests of the main Central Range along Peninsular Malaysia to the river mouth in Port Klang, into the Straits of Malacca. Water quality was monitored at 20 stations, nine of which are situated along the main river and 11 along six tributaries. Data was collected from 1997 to 2007 for seven parameters used to evaluate the status of the water quality, namely dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, suspended solids, ammoniacal nitrogen, pH, and temperature. The data were first investigated using descriptive statistical tools, followed by two practical multivariate analyses that reduced the data dimensions for better interpretation. The analyses employed were factor analysis and principal component analysis, which explain 60 and 81.6% of the total variation in the data, respectively. We found that the resulting latent variables from the factor analysis are interpretable and beneficial for describing the water quality in the Klang River. This study presents the usefulness of several statistical methods in evaluating and interpreting water quality data for the purpose of monitoring the effectiveness of water resource management. The results should provide more straightforward data interpretation as well as valuable insight for managers to conceive optimum action plans for controlling pollution in river water.

Assessing the suitability of stream water for five different uses and its aquatic environment

Surface water is one of the essential resources for supporting sustainable development. The suitability of such water for a given use depends both on the available quantity and tolerable quality. Temporary status for a surface water quality has been identified extensively. Still the suitability of the water for different purposes needs to be verified. This study proposes a water quality evaluation system to assess the aptitude of the Selangor River water for aquatic biota, drinking water production, leisure and aquatic sport, irrigation use, livestock watering, and aquaculture use. Aptitude of the water has been classified in many parts of the river segment as unsuitable for aquatic biota, drinking water production, leisure and aquatic sport as well as aquaculture use. The water quality aptitude classes of the stream water for nine locations along the river are evaluated to contribute to decision support system. The suitability of the water for five different uses and its aquatic ecosystem are verified.