Potable Water Treatment Plant Research Articles

Assessment of Phytotoxicity of Potable Water Treatment Plant Sludge-bound Compost Pellets on Seed Germination of Radish (Raphanus sativus L.)

Binding loose compost into pellets needs different binding materials. Maintenance of pellet stability highly depends on the binding materials used. Potable water treatment plant sludge (WTPS) has the potential to be used as a binding material due to the high content of clay, organic matter, and nutrients. However, compost and WTPS may contain heavy metals, toxic compounds, salts, and growth inhibitors. Therefore, the determination of the phytotoxicity of WTPS bound compost pellets is essential before amending them to the soil. The present study aimed to assess the phytotoxicity of different pelleted compost using seed germination bioassay of Raphanus sativus L. Four compost pellets were considered (T1: commercial compost pellet (100% compost), T2: commercial integrated pellet (90% compost+10% inorganic fertilizer), T3: WTPS-bound compost pellet (90% compost+10% WTPS), T4: WTPS-bound integrated pellet (80% compost+10% WTPS+10% inorganic fertilizer)) and pellet aqueous extracts (PAE) were prepared, respectively. Distilled water was used as the control. The dilution sequence of PAE as 50% and 100% were tested for seed germination in Petri dishes in a randomized design with three replicates. pH, EC, and selected heavy metals (Al, Zn, Cu and Cr) were determined in PAE. RSG% (Relative Seed Germination %), RRG% (Relative radicle Growth %), and GI% (Germination Index) were calculated for all the PAE after 72 hours. The PAE had a pH range from 6.8-7.2. The Cr was not detected in all 100% PEA. The highest levels of Al and Zn were detected in 100% PAE of T1. All the treatments in both 50% and 100% PAE showed GI% higher than 80% except the 100% PAE of commercial integrated pellet (T2) and WTPS-bound integrated pellet (T4). The PAE from the T2 and T4 showed low RSG% and RRG% and thereby the GI% is low due to high EC in PAE. The GI% of 100% PAE in T2 and T4 was 32.33% and 67.25%, respectively. The lowest values for RSG% and RRG% were recorded for T2 as 44.44% and 72.75%, respectively. Spearman‘s Rank Correlation coefficients were calculated for EC with RSG%, RRG%, and GI% and all variables showed negative correlations as (-0.44), (-0.97), and (-0.69), respectively. This indicates that high EC reduces radical growth and seed germination. PAE at 100% concentration levels of commercial integrated pellet showed high phytotoxicity, and WTPS-bound integrated pellet showed less phytotoxicity while other treatments did not show any sign of phytotoxicity. All the PAE at 50% concentration level were free from phytotoxicity. Hence, 10% WTPS in w/w basis can be used as a binding agent in pelletizing loose compost. Different WTPS concentrations should be tested in binding process for its optimum utilization. 
 Keywords: Bioassay, Compost, Phytotoxicity, Radish, Water treatment plant sludge

Assessment of phytotoxicity of potable water treatment plant sludge-bound compost pellets on seed germination of radish (Raphanus sativus L.)

Maintenance of compost pellet stability highly depends on the binding materials used. Potable water treatment plant sludge (WTPS) has the potential to be used as a binding material due to its high content of clay, organic matter, and nutrients. Compost and WTPS may contain heavy metals, toxic compounds, salts, and growth inhibitors and they may be phytotoxic to the plants. The present study aimed to assess the phytotoxicity of different pelleted compost using a seed germination bioassay of Raphanus sativus L. Pellet aqueous extracts (PAEs) were prepared from four types of compost pellets (T1: commercial compost pellet, T2: commercial integrated pellet, T3: WTPS-bound compost pellet, T4: WTPS-bound integrated pellet). The dilution sequence of PAEs at 50% and 100% concentrations were tested for seed germination in Petri dishes in a randomized design with three replicates. pH, EC, and selected heavy metal concentrations (Al3+, Zn2+, Cu2+, and Cr6+) were determined in PAEs. Relative Seed Germination % (RSG%), Relative Radicle Growth % (RRG%), and Germination Index (GI) were calculated for all the treatments after 72 hours. RSG%, RRG%, and GI showed negative correlation with EC. PAEs of T2 showed high phytotoxicity, while T4 showed less phytotoxicity at the 100% concentration level, whereas other treatments did not show any signs of phytotoxicity. All the PAEs at 50% concentration level were free from phytotoxicity. Hence, 10% WTPS on a w/w basis can be used as a binding material in pelletizing loose compost.

Technical and Managerial Measures to Reduce the Environmental Risks Generated by the Activities Carried out at Zăoaga Water Treatment Plant

Abstract Environmental risk can result from the interaction between human activity and the environment. Human activities can generate certain changes in the environmental components, thus inducing a potential danger for the health of people, flora, vegetation and fauna through the negative effects they have on water resources, air and soil quality, climate, microclimate, and so on. This paper presents the potable water treatment plant from Zănoaga, located in Petroșani Municipality, and highlights the potential risks related to the activity within this plant. Particular emphasis is placed on the risk to the environment and human health that may arise from improper storage and handling of liquid chlorine tanks, chlorine being a toxic gas if found in high concentrations in air, water or soil.

Potential reuse of sludge from a potable water treatment plant in Al Hoceima city in northern Morocco

Producing potable water generates a large amount of sludge, which consumes energy and must be managed and controlled. A case study of a potable water production plant in Al Hoceima City in northern Morocco is described here. The plant produces 15000 ​m3 of potable water each day to meet the water demand of Al Hoceima City, and this causes 3 ​t of sludge to be produced each day. Sludge extracted while producing potable water was characterized, and the possibility of reusing the sludge rather than disposing of it directly to the environment was assessed. The pH, turbidity, aluminum content, and other characteristics of the sludge were determined. Jar tests were performed to determine the optimum coagulant (aluminum sulfate) dose to ensure that the minimum required amount of aluminum sulfate was used. The characterization results indicated that the sludge was stable and reusable. The jar-test results allowed the amount of coagulant used to be optimized and will lead to markedly less sludge being disposed of than is currently the case.

DISPERSION MODELING AND ANALYSIS OF ACCIDENTAL RELEASE OF CHLORINE: CASE STUDIES OF THREE SELECTED LOCATIONS IN NIGERIA

Chlorine is a toxic chemical that is nonetheless commonly employed for many industrial applications such as disinfection of water in potable water treatment plants. Accidental release of chlorine at such a facility can lead to serious environmental pollution with high adverse health consequence for both personnel and residents close to the facility. Two reported accidental releases of chlorine at water treatment plants were at the Cross River Water Board Plant and the Lamingo Water Treatment Plant which occurred in 2007 and 2015, respectively, and resulted in multiple fatalities and several hospitalizations. This paper, therefore, presents the dispersion modeling of these two cases together with a third one based on hypothetical release scenarios in order to determine the potential consequences of the releases. The modeling was carried out using the Areal Location of Hazardous Atmosphere (ALOHA) software developed and made freely available by the United State Environmental Protection Agency (US EPA). The Google Earth mapping software, which is also freely available, was employed to graphically display the results of the dispersion modeling from the ALOHA software so that it is easy to identify the areas that could be impacted by the releases. The results showed three threat zones (red, orange and yellow) for all the hypothetical release cases of the three locations. The results also show that the potential for much higher multiple fatalities and hospitalizations exist for the third location. Thus, every effort must be made by implementing measures to prevent the accidental release of chlorine, as well as adequate/robust emergency response plans for mitigation and recovery in the event of a release. The dispersion modeling results are useful for planning emergency response and evacuation/escape routes. Keywords: Dispersion modeling, Chlorine, Toxicity, ALOHA software, Google Earth, Threat zones, emergency response planning.

Potable Water Supply Deficiency in Yaounde (Centre Cameroon): Challenges and Coping Strategies of the Inhabitants

In most cities in developing countries, dwellers continue facing difficulties in adequately accessing potable water in sufficient quantity for their daily needs. These difficulties are perceived by households each time they fetch drinking water or try to get access to potable water for other household activities. This study aims to assess the problem of potable water supply in the Yaounde III Subdivisions’ neighbourhoods and the coping strategies developed by citizens to meet their needs. To achieve this objective, 300 households were selected and investigated based on purposive and systematic random sampling, particularly in the most densely populated neighbourhoods. We proceeded by identifying the different water supply sources of households for their various needs, and assessing the difficulties encountered in getting water and how they overcome them. Results reveal that in Yaounde III Subdivision only 34.33% of the households are supplied by the Cameroon Water Utilities Corporation (CAMWATER), while 65.67% rely on alternative water supply sources (wells, drillings and springs) without any pre-treatment. Among those connected to CAMWATER network, 46.6% do not have a regular water flow. Results also revealed that water sources were located at reasonable distances (less than 1 kilometre) and that 70% of households take less than 30 minutes to fetch water. Failure in water supply is mainly caused by the insufficient pumping capacity of the existing potable water treatment plants which lead to rationing and shortages, but also to rapid population growth and city extension not followed by the extension of the potable water distribution network. To fill the gap in water supply, it is imperative for public authorities to quickly achieve the project on water supply from the Sanaga River. Also, CAMWATER should extend its distribution network and improve its maintenance system.

Characterization and Potential Reuse of Sludge Issued from Potable Water Treatment Plant of Al Hoceima

Characterization and Potential Reuse of Sludge Issued from Potable Water Treatment Plant of Al Hoceima

Assessment of sediment arsenic and iron occurrence and leaching potential in a potable water treatment plant wastewater stabilization pond system

Wastewater stabilization ponds (WSPs) are commonly used to reduce wastewater metal(loid) concentrations from drinking water treatment plants (DWTPs) through sedimentation. However, this results in increased sediment concentrations that can be released back into the overlying water. Thus, our goal was to evaluate the WSP metal(loid)s occurrence and leaching potential. Currently, a Saskatchewan based DWTP’s WSP system was investigated given historically elevated effluent As and Fe concentrations. The WSP consists of five ponds that were sampled on six occasions in 2019 and 2020. In addition, sediments were used in laboratory-based experiments to determine their leaching potential. Overall, the sediments were found to contain elevated concentrations of As and Fe of 25 to 400 mg/kg and 10 000 to 45 000 mg/kg, respectively. Leaching experiments indicated that the pond sediments could potentially release As and Fe with log Kd values ranging from 2.21 to 4.31 L/kg, whereas Fe ranged from 3.32 to 5.53 L/kg.

Removal of polycyclic aromatic hydrocarbons (PAHs) in conventional drinking water treatment processes

The presence of polycyclic aromatic hydrocarbons (PAHs) in water poses a serious threat to the human health due to their toxic effects. Therefore, the removal of these compounds from drinking water in Potable Water Treatment Plants (PWTPs) should be evaluated and optimized to assure the quality of water intended for human consumption. In this work, changes in PAHs levels during drinking water treatment processes have been monitored to evaluate the effectiveness of conventional processes in the removal of these recalcitrant pollutants. Several chemical treatment methods based on the addition of KMnO4, FeCl3 and NaClO were evaluated through jar tests. The analysis of PAH content of aqueous samples was carried out by gas chromatography coupled with mass spectrometry. The highest removal efficiency, over 90%, was obtained for benzo(a)anthracene, benzo(a)pyrene and dibenzo(a,h)anthracene. The most recalcitrant compounds to degradation were fluorene, anthracene, phenanthrene and flouranthene with reduction rates between 45 and 57%. The conventional treatment processes assessed have been proved to be effective reducing the PAH below the legal limits of drinking water quality. The definition of a parameter based on chemical properties of PAHs, i.e., sorption capacity and energy required to remove an electron, enabled the prediction of removal rate of pollutants which represents a valuable information for the plant operation.

Denver Water Optimizes Filter Valve Flow Control

Filter flow smoothing helps Colorado's largest potable water treatment plant stabilize total filter effluent rate and improve finished water pH adjustment to meet stringent corrosion‐control goals.

Integrated modelling and management of manganese for a conventional potable water treatment plant

A reliable simulation of the manganese cycle in water supply system is essential for timely and effective manganese treatment strategies. A data-driven model estimating manganese levels in the treated water was developed through a threshold-based approach using raw water and supernatant return manganese levels. This data-driven model and a three-dimensional manganese cycle model for the source reservoir were integrated to simulate the overall manganese variations from the lake to the treated water. A decision support system based on the developed data-driven model was established to allow operators to react to situations that could result in elevated levels of manganese in the treated water. Scenario analyses were completed to examine the manganese variations in the reservoir, raw water and treated water due to different precipitations and wind conditions and to allow the identification of optimal strategies for manganese management from the reservoir to the water supply system.

The influence of certain ecological parameters on a potable water treatment plant in El-Dakahleyia Province.

The influence of certain ecological parameters on a potable water treatment plant in El-Dakahleyia Province.

Operating parameters optimization of combined UF/NF dual-membrane process for brackish water treatment and its application performance in municipal drinking water treatment plant

As an important water resource, brackish water has been extensively utilized in the industry. However, there are few cases of municipal potable water treatment plants that use low chloride content brackish water as the source. In this paper, the brackish water treatment efficiency of ultrafiltration (UF)/nanofiltration (NF) dual-membrane process was evaluated in a municipal potable water treatment plant, combining with a pilot optimization experiment. Results showed that UF guaranteed the inlet water quality of NF and NF could efficiently reject organics and salts, with a chloride removal over 95 %. Pilot experiment showed that the UF membrane flux decreased only 12 % after continuously 30-days operation under the optimized UF operation conditions, effectively extending the chemical cleaning interval. Response surface method was adopted in the NF removal efficiency and energy consumption optimization. With the increase of feed water conductivity, the influences of pressure and recovery on the removal efficiency were strengthened, and the removal efficiency could be regulated over a wider range. When the conductivity was less than 3500 μS/cm, NF could perform high treatment efficiency under the operation pressure of 0.65−0.85 MPa and recovery of 55–70 % . Besides, as feed conductivity increased, it was necessary to increase the pressure and reduce the recovery within this range to maintain efficient operation. This paper will provide a guidance for the UF/NF dual-membrane process design and operational optimization.

Solar energy in the operation of the municipal aqueduct of González department of Cesar

The Cesar´s Department has presented historically problems in terms of availability energy, which has hindered the implementation and continuity of some projects. One of the alternatives solutions focuses on the use of solar energy in this area, considering that the highest daily average brightness values are in the Caribbean region and the Orinoquia. For this reason, the Municipality of González, in the Cesar Department, promoted the construction of the first aqueduct in Colombia that operates only with hydraulic and solar energy, which ensures continuity in the drinking water service, and the contribution with the reduction of CO2 emissions at the atmosphere , In order to minimized the use of fuel for this operation. In support of the above investigation, the object of the present project has two main ideas; the first one is estimate the radiation potential in the municipality of González and the second one is establish the dimensions of the photovoltaic solar system to take advantage of this kind of energy. The mathematical model selected, is an empirical one proposed by Bristow-Campbell, based on the availability of information, and the match presented in previous studies , in which was analized secondary information, coming from the Aguas Claras Airport weather station, and the information available on the POWER page, that is a set of solar and meteorological data from NASA’s researchs for renewable energy. For the evaluation of the photovoltaic solar system, it was used a methodology based on the radiation potential available in the area, the energy requirement in the operation of the drinking water treatment plant, the administrative and laboratory facilities of the municipal aqueduct and the measure that were used of the generation, accumulation and investment regulator subsystem. It was conclude that the radiation potential for the Municipality of González, is estimated in a range between (4.5 and 6) KWH/m2/day, and that value is enough to meet th average, as well as the measurement proposed, have the capacity to supply electricity in the operation of the potable water treatment plant, the administrative and laboratory facilities of the aqueduct.

Effects of De-Oiled Jute Seed and Cottonseed Extracts as Natural Polymeric Coagulants for Surface Water Treatment

Developing countries are currently facing intense drinking water shortages due to paucity of funds to set-up potable water treatment plants. This has led to the outbreak of water-borne diseases resulting in huge medical spending for the government. Employing natural biopolymers (Cottonseed (Gossypium hirsutum) [CS] extracts and de-oiled Jute seed (Corchorus olitorius) [JS]) for surface water treatment presents an alternative to improving the quality of drinking water in rural communities. This study was therefore aimed at comparing the effectiveness of the two natural bio-polymers for improving surface water quality. The oils were extracted using n-hexane as extractor solvent (with water at about 40-70°C) for six (6) hours and the seed residues were used to prepare extract stock solutions for the water treatment. Measured water samples (100 ml) were treated using the bio-polymer extracts employing different doses (10, 20, 30, and 40 ml). Physico-chemical analysis of the treated samples using CS and JS extracts yielded optimum treatment values of 7.2 and 6.89 for pH; 24.45 and 19.48 NTU for turbidity; 92.41 and 0.52 μs/cm for conductivity; 120.55 and 149.67 mg/l for BOD while 208.82 and 237.32 mg/l were recorded for COD. These corresponds to total reduction efficiencies of 14.98 and 34.31% (pH); 32.19 and 58.37% (Conductivity), 55.5% and 64.56% (turbidity), 36.86 and 60.4% (BOD) and 52.34 and 64.40% (COD) for CS and JS respectively. These results show the potentials and limitations of the two biopolymers as alternative coagulants if applied at optimum concentrations. They can be utilized to reduce waterborne diseases in rural communities lacking basic water treatment facilities.

Nueva metodología para el diseño rápido de sistemas de potabilización de agua en la enseñanza universitaria en Ingeniería ambiental

A nivel mundial día a día las fuentes de recurso hídrico superficial dotadas con cualidades aptas para consumo humano disminuyen resultando en afecciones a comunidades dependientes de dichas fuentes de este preciado recurso. Dada la situación actual, la opción más viable para favorecer a comunidades aisladas o alejadas es mediante la construcción de pequeñas plantas de tratamiento de agua potable (PTAP´s) con módulos de diseño rápido y sistematizado que permita obtener las especificaciones para su construcción y operación en forma segura y sostenible con el tiempo cumpliendo con el ODS 6 (Agenda 2030, ONU). Dentro de este contexto, el diseño de sistemas para la obtención de agua potable se convierte en una herramienta valiosa que permite la configuración rápida de este tipo de infraestructura para levantar sistemas eficientes y completamente sostenibles en comunidades con escaso recurso hídrico. Actualmente, la enseñanza de este tipo de conceptos y fundamentos se encuadran en las curriculas de programas y escuelas profesionales a nivel universitario que imparten la especialización en ingeniería ambiental con escaso nivel informático y sistematizado decayendo en su aplicación por su manejo tradicional con cálculos tediosos y lentos en la obtención de resultados. Por ello en este estudio se propone una nueva dinámica de aprendizaje utilizando la aplicación de software de modelado 3D para el estudio de casos reales con aplicación práctica y resolución inmediata permitiendo el pleno desarrollo de la capacidad crítica en el grupo de alumnos que la utilizarán.

Pathogen inactivation and by-product formation in a full-scale contact tank

Conventional designs of chlorine contact tanks in potable water treatment plants are insufficient in terms of disinfection efficiency due to low hydraulic and mixing efficiencies. Strong interaction of the turbulent flow with the solid baffles may adversely affect hydraulic, mixing and disinfection performance of the contact system. Recirculating and jet zones created in the tank may require high chlorine dosages to yield adequate disinfection levels, which can result in the formations of high disinfection by-products (DBPs) in the treated water. The use of treated water by the consumers with high chlorine dosages and DBPs may lead to environmental and health problems in the long-term. Disinfection efficiency of the tank can be increased by the modification of the baffles and required disinfection levels can be achieved using lower chlorine dosages. In this study, performance of a patented baffle design is evaluated by means of numerical simulations on a full-scale contact tank. Self-decomposition of the chlorine, pathogen inactivation and formation of Trihalomethane (TTHM) by-product are simulated using a second-order numerical model. Numerical results show that the new baffle design yields 3-log inactivation by using 40% less chlorine concentration than the conventional design and the amount of DBP can be decreased by 43%.

Diagnosis, recommendations and optimization for potable water treatment plant in Cauca (Colombia)

Currently the water supply system in the municipality of Corinto (Cauca) in Colombia provides drinking water to the entire urban and rural population of the municipality. In order to provide drinking water to the entire population, it became necessary to optimize and/or expand the existing water treatment plant. The article presents an assessment of the consideration of two optimization options: the need for reconstruction of existing water treatment facilities or the construction of additional water treatment units. A reasonable proposal was made to expand the station by building additional water treatment units, including advanced modern water treatment technologies, such as coagulation, flocculation, sedimentation, filtration, sorption, settling using thin-layer modules and disinfection, based on the survey (diagnostics), technical and economic analysis, analysis of the efficiency of the existing water treatment plant, taking into account the quality of drinking water preparation, confirmed by the analysis of samples, the results of physical, chemical and microbiological tests, indicating the optimal quality of drinking water for human consumption. The use of modern water treatment technologies will allow to achieve the required quality of purified sufficient water for drinking purpose.

Determination of natural radionuclides in waste generated in the potable water treatment plants of the Zona da Mata of the state of Pernambuco- Brazil

The water purification procedure aims to obtain a product appropriate for human consumption, minimizing the presence of contaminants and toxic substances present in the water. Among these contaminants, some radionuclides of natural origin, such as uranium, thorium and their descendants, have been identified. Studies have shown that the stages of purification are quite effective in removing the radionuclides contained in water. The removal is due to co-precipitation of the radionuclides with the suspended materials and the precipitated material is accumulated and characterized as a Technologically Concentrated Natural Occurrence Radioactive Material (TENORM) by the United States Environmental Protection Agency (USEPA). This residue can present significant levels of radioactivity and, when discarded in the environment without any treatment, can generate a problem of environmental impact and a risk to the health of the population. In this way, some gamma emitters of the series of U, Th and the K-40 were determined in the residues generated at the Potable Water Treatment Plants – PWTPs in six municipalities of Pernambuco. The results obtain corroborate the classification of the residues generated in the PWTPs as concentrators of the radioactive components contained in the water supplied to the system and reinforce the need for the release to the environment, which is the usual way of disposal of this waste, to be carried out only after considering the radiological protection standards established.

OPTIMIZATION OF DONNAN DIALYSIS FOR ALUM RECOVERY USING BOX BEHNKEN DESIGN

Most potable water treatment plants use aluminium salts as coagulants. This generates a lot of treatment residue which consist of a high amount of aluminium in the residue matrix. Recovery of the alum-coagulant from the potable water treatment for reuse provides direct process and economic advantages. Donnan Dialysis is an ion exchange process that has a proven advantage in coagulant recovery. The commercial application of this process requires bench scale optimization before implementation. In this study, a response surface methodology is applied to the Donnan system. Incorporated with the Box-Behnken experimental matrix, the main and interactional effects of input variables for optimum alum recovery was determined. The Nafion 117 cation exchange membrane was used. Using experimental results, the quadratic statistical module generated was significant with a low P-value (<0.001). The statistical prediction from experimental results shows that high recoveries of 85-96% can be achieved.