Chemical and membrane desalination of natural water with high content of iron-organic compounds

Under the conditions of modernization of Russian thermal power plants (TPP), water treatment plants based on imported membrane technologies are often put into operation without consideration of the quality of the source (natural) water and variable-performance operating modes. At the same time long-running water treatment plants and their capabilities are not considered. In this regard, the cost of additional water is three or more times higher, and the average output is respectively lower than at traditional water treatment plants. Often, one doesn’t take the advantages of reverse osmosis installations based on the rejection of the use of aggressive reagents such as sulfuric acid, etc. The aim of the study is to increase the efficiency of desalinated water production. It is especially important to conduct studies of natural waters with high content of iron-organic compounds characteristic of the regions of the center and north of Russia. The authors have carried out laboratory studies of various, primarily new filter materials, regents, and devices, both at the stages of pre-purification of water i.e., clarification, and at the stages of demineralization of clarified water. Water treatment plants of Ivanovo combined-cycle plant (CCP) and Cherepovets state district power station (GRES) are considered as the subject of the research. It is found out that if one applies ion-exchange and membrane water treatment technologies to treat water with high content of iron-organic compounds, high-quality desalinated water can be obtained. The properties of water are the following: specific electrical conductivity of no more than 0,2 mcm/cm and permanganate oxidizability of no more than 1 MgO/l. Results of studies at the Ivanovo CCP and Cherepovets GRES have shown practicability to coagulate water with aluminum sulfate using an anionactive flocculant, for example, during the flood period. Application of coagulation and ultrafiltration units before reverse osmosis installation ensures removing organic impurities from the water. Based on the obtained research results, recommendations are given for the implementation of the results at Ivanovo water treatment plants.

Stopping Macroplastic and Microplastic Pollution at Source by Installing Novel Technologies in River Estuaries and Waste Water Treatment Plants: The CLAIM Project

Marine pollution from debris is a major issue nowadays, since every year large amounts of litter enter into the sea. Under the Horizon 2020 framework and within the Cleaning Litter by developing and Applying Innovative Methods in European Seas (CLAIM) project, innovative devices were designed, developed, tested and applied in laboratory and in the field. These consisted of a system named CLEAN TRASH for the prevention of macrolitter in river estuaries before entering the Sea and a filtering system for microplastics (MPs), to be placed at waste water treatment plants (WWTP). Laboratory experiments showed that macrolitters were blocked by 90% by the CLEAN TRASH system, while during the sea testing period at the Kifissos river estuary, a significant source of terrestrial based litter for the Saronikos Gulf, a total amount of 1,175 kg of litter was collected in 38 days before entering the sea, of which the 708 kg (60%) were plastic debris of various sizes and another 164 kg (14%) of styrofoam parts. The lab scale prototype of the filtering system for MPs had an efficiency of about 95%. The upscaled device was tested at the Megara WWTP and was able to withhold a significant amount of MPs. The theoretical contribution of such devices toward the reduction of plastic pollution in the Saronikos Gulf area and the Natura conservation areas therein, was also studied with the use of a 3-D coupled Hydrodynamic-Lagrangian litter tracking model. In all experiments performed, the installation of the above devices for a period of 2 years, resulted in a microplastics reduction by about 87% and a macroplastics reduction ranging from 13 to 43%, depending on the sources.

Effect of clariflocculator and pulsator based sedimentation technology and poly-aluminium chloride coagulant type on the efficiency of the water treatment plant

Polyaluminium chloride (PAC) with different basicity is used as a coagulant in most drinking water treatment plants (WTP). The aluminium concentration in PAC and its hydrolysis mechanism varied with the basicity of PAC. Incremental addition of PAC changes various Physico-chemical properties and turbidity removal mechanisms in water. Water treatment plants use the PAC concentration beyond its optimum dose without considering other aspects, including residual aluminium concentration. In the present work, the effect of high and medium basicity of PAC on different Physico-chemical properties like pH, zeta potential, and residual aluminium concentration of water was investigated. The pH of treated water decreases with the incremental addition of PAC, and an increase in zeta potential and residual aluminium concentration in treated water was evidenced. The change in pH after PAC addition is responsible for deciding the coagulation mechanism and efficiency of the coagulation process. pH reduction is comparatively more in high basicity PAC than medium basicity. PAC hydrolysis mechanism is controlled by the zeta potential of water and can be used as an alternative method to decide the optimum coagulant dose. The performance of clariflocculator and pulsator-based WTP was also evaluated for raw water from the same source. To reduce down the turbidity below the acceptable level, the coagulant requirement for clariflocculator based WTP is comparatively less than pulsator based WTP. The floc blanket in the pulsator gets disturbed with a slight change in the coagulant chemistry and quantity.

Assessment of Sediment Arsenic and Iron Occurrence and Leaching Potential in a Potable Water Treatment 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 with 25 to 400 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, while Fe ranged from 3.32 to 5.53 L/kg.

Simulating sediment discharge at water treatment plants under different land use scenarios using cascade modelling with an expert-based erosion-runoff model and a deep neural network

Excessive sediment discharge in karstic regions can be highly disruptive to water treatment plants. It is essential for catchment stakeholders and drinking water suppliers to limit the impact of high sediment loads on potable water supply, but their strategic choices must be based on simulations integrating surface and groundwater transfers and taking into account possible changes in land use. Karstic environments are particularly challenging as they face a lack of accurate physical descriptions for the modelling process, and they can be particularly complex to predict due to the non-linearity of the processes generating sediment discharge. The aim of the study was to assess the sediment discharge variability at a water treatment plant according to multiple realistic land use scenarios. To reach that goal, we developed a new cascade modelling approach with an erosion-runoff geographic information system (GIS) model (WaterSed) and a deep neural network. The model was used in the Radicatel hydrogeological catchment (106 km2 in Normandy, France), where karstic spring water is extracted to a water treatment plant. The sediment discharge was simulated for five design storms under current land use and compared to four land use scenarios (baseline, ploughing up of grassland, eco-engineering, best farming practices, and coupling of eco-engineering/best farming practices). Daily rainfall time series and WaterSed modelling outputs extracted at connected sinkholes (positive dye tracing) were used as input data for the deep neural network model. The model structure was found by a classical trial-and-error procedure, and the model was trained on 2 significant hydrologic years. Evaluation on a test set showed a good performance of the model (NSE = 0.82), and the application of a monthly backward-chaining nested cross-validation revealed that the model is able to generalize on new datasets. Simulations made for the four land use scenarios suggested that ploughing up 33 % of grasslands would increase sediment discharge at the water treatment plant by 5 % on average. By contrast, eco-engineering and best farming practices will significantly reduce sediment discharge at the water treatment plant (respectively in the ranges of 10 %–44 % and 24 %–61 %). The coupling of these two strategies is the most efficient since it affects the hydro-sedimentary production and transfer processes (decreasing sediment discharge from 40 % to 80 %). The cascade modelling approach developed in this study offers interesting opportunities for sediment discharge prediction at karstic springs or water treatment plants under multiple land use scenarios. It also provides robust decision-making tools for land use planning and drinking water suppliers.

Investigation of factors of the appearance of odor in river water at the water intake of Rostov-On-Don

The paper presents a study of quality of natural waters and water in a centralized water supply system during the period of an increase in the “Smell” indicator in the spring of 2021. The chemical and physical properties of water, the results of quality and quantity of studying the variety I phytoplankton in the most difficult period of deterioration in quality of river water. Low water and exceeding MPC concentrations of organic substances in river water. The Don River causes altered form odorant substance as evidenced by the results of determination in water 1,2,3- t rihlorbenzol and geosmin, hexachloroethane and aniline shown in operation. Barrier function of reagent treatment methods used at water treatment plants in the lower reaches of the river. The Don River, even when combined with carbonated water, is deficient in odor-producing substances.