Water Purification Process Research Articles

Engineered diatomic catalyst empowered electro-Fenton processes for advanced water purification

This work introduces the selection and preparation of DACs for the 2 + 1e− ORR EF process and concludes with a discussion on challenges and future directions for the intelligent design of electrodes and reactors in EF purification technologies.

Nanocosmos of catalysis: a voyage through synthesis, properties, and enhanced photocatalytic degradation in nickel sulfide nanocomposites.

Nanomaterials play a decisive role in environmental applications such as water purification, pollutant monitoring, and advanced oxidation-based remediation processes, particularly in semiconductor and metal sulfide-based photocatalysis. Metal sulfides are ideal for photocatalysis because of their unique optical, structural, and electronic characteristics. These properties enable the effective use of solar energy to drive various catalytic reactions with potential uses in environmental remediation with sustainable energy production. Among them, nickel sulfides (NiS) stand out for their narrow band gaps, high stability, and cost-effectiveness. This review thoroughly analyzes recent advancements in employing nickel-sulfide-based nanostructures for water decontamination. It begins by addressing environmental material needs and emphasizing the properties of nickel sulfide. To improve photocatalytic performance, controlled processes that affect the active structure, shape, composition, and size of nickel sulfide photocatalysts are examined, along with their synthesis methods. The heart of the review article is a detailed analysis of the modification of NiS through metal and non-metal doping, heterojunction, and nanocomposite formation for enhanced photocatalytic performance. The discussion also includes metal-modified nanostructures, metal oxides, and carbon-hybridized nanocomposites. This study underscores notable advancements in the degradation efficiency of NiS photocatalysts, rivaling their costly noble-metal counterparts. The analysis concludes with potential future directions for nickel sulfide-based photocatalysts in sustainable environmental remediation.

Analytical Review of Microplastics Occurrence in Bottled Water, Tap Water, and Wastewater Treatment Plants

Currently, water availability and accessibility have become more challenging due to population growth, development of industrial and agricultural activities, and the effects of climate change. Various types of pollutants released by human activities threaten water quality and availability. Microplastics and emerging contaminants are currently affecting water resources and posing a risk to human health. The present study reviews the available studies that analyzed the abundance, shape, and size of microplastics in water, including glass, plastic, reusable, recyclable, and beverage bottled water, tap water, and wastewater treatment plant (WWTP) influent and effluent. Analysis of the collected data allowed comparison of microplastic abundance in different packaging water bottles, tap water, and raw and treated water from WWTPs. The analysis results suggest that microplastics in drinking water are mainly associated with water sources. Therefore, more attention should be paid to water treatment and purification processes and technologies. The type of packaging is also a crucial parameter to consider when quantifying microplastics in drinking water, although the use of glass bottles is recommended to minimize the potential associated risk to humans and ensure safe consumption. Increasing public awareness and knowledge about waste separation, the potential risks of microplastics to human health, and the urgent need for behavioral change in the management of waste, mainly plastic objects, remain the main keys to reducing the number of plastics entering our environment and our bodies.

USE OF MICROWAVE RADIATION FOR EFFECTIVE PURIFICATION OF WASTEWATER FROM ORGANIC COMPOUNDS

This article is devoted to the problem of using microwave radiation as a potentially effective method of cleaning wastewater from organic compounds. The problem of cleaning wastewater from organic contaminants in the food industry requires highly effective methods since protein compounds in wastewater can cause environmental hazards and complicate the cleaning process. The purpose of the work was to investigate the effectiveness of using microwave radiation to purify wastewater from organic compounds, particularly protein impurities, and to establish the possibilities of this method for improving the process of water purification in the food industry. The article mainly examines the use of microwave radiation for this purpose and analyses its effect on proteins usually present in wastewater from the food industry. Experimental studies have shown the possibility of adequate wastewater treatment using microwave radiation. The advantages of using microwave heating, as well as its speed and regulation accuracy, are analysed, making this method attractive for use in wastewater treatment and other industrial production processes. The study includes an analysis of microwave radiation's effect on proteins commonly present in wastewater from the food industry. The research methodology involves modelling the composition of wastewater and using a microwave oven to process protein solutions. The results of the experiments demonstrate the possibility of adequate wastewater treatment using microwave radiation, which opens up prospects for further use of this method in industry and environmental protection. The results indicate the success of using microwave radiation to purify wastewater from organic compounds, notably protein pollution.

Magnetic Modification of Ion Exchange Processes

Today, the ion exchange method is widely used in water treatment systems. Ion exchange systems are used to correct the mineral composition of water to the required standards; wastewater treatment; desalination and softening of natural waters. To present day, there are technical solutions to improve the process of water purification, treatment, softening and demineralization. They include: improvement of physical and chemical conditions; intensification of the ion exchange process; use of new ion exchange materials; modification of ion exchange resins; combination with other water treatment methods; modernization of equipment and designs of ion exchange devices. In order to improve the flow conditions and reduce the burden on the environment, it is promising to implement technologies aimed at intensifying the ion exchange process by activating the components of the process. The paper investigates the effect of magnetic modification on the intensification of ion exchange processes during the adjustment of the mineral composition of natural waters. The obtained results demonstrate the influence of the magnetic field on the ion exchange process.

Computer simulation of a solar multi-effect distillation multi-stage flash effluent purification system

Abstract This study integrates multi-effect distillation (MED), multi-stage flash (MSF) evaporation, and solar interface evaporation technologies to enhance water purification processes. We evaluate the material and performance of interface evaporators, with a particular focus on managing the energy balance in solar water evaporation. The research further develops thermal regulation in photothermal materials to maximize light absorption, minimize heat loss, and speed up steam conversion. We employ a novel approach using corn starch and ionic liquid-modified silica hydrogels, noted for their hydrophilicity and broad-spectrum light absorption. The goal is to assess these hydrogels for photothermal conversion efficiency and salt resistance, examining their evaporation performance across various media—pure water, highly saline water, and oily wastewater—and their effectiveness in purifying industrial sewage. Monomer [VEIm]Br and cross-linking agent polymerization occurred to prepare the obtained SiO 2 – PILs.Ag / PPy / SiO 2 – PILs surface of polypyrrole and Ag particles presenting a three-dimensional porous structure is able to enhance the light absorption performance, between 200-2500 nm range of light absorption rate as high as 90%. Experiments proved the introduction of ionic liquid grafted silica on the introduction of the mechanism to improve the thermal insulation and salt resistance for the actual wastewater purification to provide a strategy.

THE ECOLOGICAL COMPONENT OF THE DEVELOPMENT OF THE ENTERPRISES OF THE WATER-SEWAGE MANAGEMENTS

In modern conditions, in order to ensure their own independence, enterprises of any industry are forced to constantly monitor and increase the socio-ecologo-economic efficiency of their activities. With particular acuteness, this issue is faced by communal enterprises of the water-sewage management, which is connected both with the specificity of the form of ownership and with the external regulation of activity as a subject of natural monopolies. The main purpose of the activity of the basic typical representative of the industry – is to provide services water supply and drainage, as well as the transportation of drinking water and wastewater, their treatment at the city's treatment facilities. The work examines the problem of researching the directions of development of enterprises water-sewage management, in particular the ecological component of their activity, related to the operation of treatment facilities and equipment in the process of water supply and drainage. Is analyzed the structure of the main cost elements that make up the basis of the production cost of water drainage services. The researching dynamics of historical changes in the most significant elements of expenses (which include energy-intensive elements): electricity and fuel and lubricants. Are separately examines the dynamics of historical changes in the cost of environmental costs, i.e. reagents used in the process of water purification and disinfection. A significant increase in the cost of certain elements serves as a basis for increasing tariff rates for services water supply and drainage. Measures are proposed to improve the water purification process and reduce the cost of water drainage services of the enterprise water-sewage management. Improving the quality of services water supply and drainage, in relation to drinking water and wastewater treatment, the use of the latest more efficient technologies and equipment solve ecological tasks, the efficiency of which depends not only on the improvement of the city, but also on the normal life of the population and the safe operation of industrial enterprises.

Role of Interface of Metal-Organic Frameworks and Their Composites in Persulfate-Based Advanced Oxidation Process for Water Purification.

The persulfate activation-based advanced oxidation process (PS-AOP) is an important technology in wastewater purification. Using metal-organic frameworks (MOFs) as heterogeneous catalysts in the PS-AOP showed good application potential. Considering the intrinsic advantages and disadvantages of MOF materials, combining MOFs with other functional materials has also shown excellent PS activation performance and even achieves certain functional expansion. This Review introduces the classification of MOFs and MOF-based composites and the latest progress of their application in PS-AOP systems. The relevant activation/degradation mechanisms are summarized and discussed. Moreover, the importance of catalyst-related interfacial interaction for developing and optimizing advanced oxidation systems is emphasized. Then, the interference behavior of environmental parameters on the interfacial reaction is analyzed. Specifically, the initial solution pH and coexisting inorganic anions may hinder the interfacial reaction process via the consumption of reactive oxygen species, affecting the activation/degradation process. This Review aims to explore and summarize the interfacial mechanism of MOF-based catalysts in the activation of PS. Hopefully, it will inspire researchers to develop new AOP strategies with more application prospects.

In Situ Investigation on Cl- Repellency Effect of Electrolyte Additive on NiOOH for Alkaline Sea Water Splitting

Sea water splitting can produce green hydrogen by feeding abundant sea water directly without high-qualified water purification process. However, excess cation such as Mg2+ and Ca2+ in sea water absorbs on the cathode surface, and it causes the loss of active site and activity toward hydrogen evolution reaction. At the anode side, oxygen evolution reaction (OER) should be competed with chlorine evolution reaction due to huge amount of Cl- ion, so operating in high pH electrolyte at low overpotential has been suggested to increase the selectivity toward OER. To further inhibit the adsorption of Cl-, some researchers have suggested using anion additive such as PO4 3- and SO4 2- in the alkaline electrolyte, but both adsorption stability of additive anion and the interaction between anion and metal oxide catalyst are still needed to be studied.In this study, we investigated the Cl- repellency effect of additive anion in the electrolyte to NiOOH catalyst, known as state-of-the-art OER catalyst, for alkaline sea water splitting. To observe the change in adsorbate species by additive anion, we tracked the mass change of the catalyst during the reaction through in situ electrochemical quartz crystal microbalance (EQCM). Furthermore, Cl- can change (degrade) the NiOOH structure by formation of metal-chloride complex. Through in situ Raman spectroscopy, we observed the structural stability of NiOOH in presence of anion additive as well as the adsorption stability of additive anion depending on the applied potential.

Metal-free catalysts with local fluorination regulation for peroxymonosulfate activation: Nearly 100 % singlet oxygen production for selective degradation of aqueous organic pollutants

Generating singlet oxygen (1O2) via activating peroxymonosulfate (PMS) is crucial for the selective removal of organic pollutants in aquatic environments. However, achieving efficient and selective conversion of PMS into 1O2 without consuming energy or metals remains a significant challenge. In this study, graphite phase carbon nitride (g-C3N4) was locally fluorinated via a simple polymerization method. The local fluorinated g-C3N4 (FCN) was used as a metal-free catalyst to activate PMS, enabling highly efficient degradation of 4-chlorophenol (100 %) and detoxification. The FCN/PMS system demonstrates exceptional selectivity for electron-rich pollutants, functions effectively across a broad pH range (2–10), and exhibits remarkable interference resistances to background scavenging ions and natural organic compounds. Furthermore, quenching experiments, probe tests, electron paramagnetic spin resonance measurements, electrochemical characterizations, and theoretical calculations demonstrated that 1O2 was the only reactive species in the catalytic process. Local fluorination regulated the electronic structure of g-C3N4, juxtaposing electron-rich fluorine with electron-deficient carbon dual active sites. This modification alters the electron transfer direction between PMS and g-C3N4, allowing for nearly 100 % selective generation of 1O2via dual electron transfer channels without the need for energy or metals. This study provides a new strategy for designing metal-free heterogeneous catalysts to selectively generate 1O2 in a green way and can facilitate the wider applications of advanced oxidation processes for water purification.

Change in dispersion of synthetic magnetite particles from the conditions of precipitation from iron sulfate-containing solutions

The paper analyzes the problems of the reagent method of wastewater treatment of machine–building enterprises, and the advantages of the magnetic sorption method in comparison with the reagent method are presented. The magnetosorption method, based on the treatment of a liquid with particles of a ferromagnetic material with the aim of sorption on their surface of substances to be extracted, has proven itself well not only in the purification of wastewater from impurities of heavy metals, but also from petroleum products, surfactants, radioisotopes, and suspended substances. The efficiency of water purification processes depends on the properties of the sorbent particles, such as dispersion, sorption capacity and magnetic properties of the particles. The paper presents the results on the dispersion of particles. Changes in the dispersion of synthetic magnetite particles obtained under various conditions, such as storage time, temperature, pH, K=[Fe2+]:[Fe3+] ratio, salt content, and nature of the precipitant, were studied. It is shown that with an increase in storage time, the number of small particles less than 10 μm decreases, and the number of large particles increases due to recrystallization processes. It has been determined that at 20 ℃ without the influence of a magnetic field, a suspension with a maximum content of particles with a diameter of 10 μm is formed, at a temperature of 40 – 70 ℃ particles with a size of 8 – 10 μm prevail in the suspension, and with an increase in the pH of the solution, the number of small particles in the suspension increases. Conversely, with an increase in salt content, the particle size increases with a decrease in the fraction of small particles by almost half. It is noted that at K = 0.8; 2.0, the largest number of particles (about 60 %) with a size of 10 μm are formed in the solution. It is shown that the maximum number of particles larger than 20 μm is formed using NaOH.

Physical modeling in water treatment technologies

In most cases, water pollution is associated with the presence in it of a dispersed phase of various substances, which, depending on its physical state, forms various polydisperse heterogeneous aggregate-unstable systems: suspensions, emulsions, and foams. The paper analyzes the application of physical models for the description of complex dispersed systems, analyzes the possibilities of classic modeling methods and the limits of the application of the considered models. The paper studies the influence of temperature changes (of seasonal or climatic origin) on the kinetics of gravitational sedimentation in wastewater treatment technologies. Considered models of physical processes accompanying the gravitational deposition of dispersed particles in hydromechanical sedimentation tanks, which take into account the Brownian motion of these particles, capable, as it turns out, of causing coagulation. And coagulation makes it possible to transfer pollutants into a state of dispersed phase with a larger particle size. Within the framework of the considered model, it was established that the time and speed of particle sedimentation in gravity sedimentation systems may change significantly with external temperature changes. Accordingly, the quality of cleaning in a sedimentation plant, which works on the principle of gravity, can significantly increase (when heated from the outside) or decrease (when cooled). Thus, the need to take into account temperature changes in the processes of gravitational sedimentation of particles in treatment facilities is an urgent task. The paper concluded that in order to improve the existing technologies of water purification in the conditions of a change in external conditions (temperature), combinations of purification methods are appropriate for better water purification. In particular, the method of gravity sedimentation and the method of electrochemical or electrophoretic purification, gradual or simultaneous processes of hydromechanical sedimentation of pollutants, filtering or flotation processes. The practical significance of the work lies in the fact that it concerns the search for ways to improve the existing technological processes of water purification and increase its quality.

Development of Sasirangan Liquid Waste Treatment System Using Ozonization Method Using Composite Ceramic Filter Media Based on Water Chestnut (Eleocharis Dulcis)

Sasirangan Liquid Waste (SLW) contains heavy metals and chemicals with BOD and COD concentrations exceeding the waste water quality standards in accordance with the Minister of Environment and Forestry Regulation Number P.16 of 2019. The aim of this research is to design and develop a SLW processing system using filter media and composite ceramics made from water chestnut (Eleocharis dulcis). Based on previous research, using the filtration method; filtration and adsorption; filtration, adsorption, sedimentation and ozonization. Filtration method can remove solid particles and sediment from water, so the water appears clearer. The water purification process that involves a filtration method using slow sand filter (SSF), which additional processes are needed either before or after the SSF is carried out. Meanwhile, the use of water chestnut has been carried out by several researchers due to its high active carbon content, namely 50.68%. In this research, we combine several methods including filtration, sedimentation, and ozonization. Water chestnut has a bound carbon content of 84.53% after being activated with an H2SO4 activator, where the largest porosity is found in ceramics with activated charcoal composite materials with variations of the H2SO4 activator. Apart from that, chestnut also has a cellulose content of 35.32% so it has the potential to be effective as a ceramic composite material in sasirangan liquid waste processing filters, especially as an adsorbent. The benefits obtained from the results of this research can be a scientific reference for the use of water chestnut as a filter media and composite ceramic.

Replacing traditional pretreatment in one-step UF with natural short-distance riverbank filtration: Continuous contaminants removal and TMP increase relief

Scientists have been focusing on applying more natural processes instead of industrial chemicals in drinking water treatment to achieve the purpose of carbon emissions reduction. In this study, we shortened the infiltration range of riverbank filtration, a natural water purification process, to form the short-distance riverbank filtration (sRBF) which retained its ability in water quality improvement and barely influenced the groundwater environment, and integrated it with ultrafiltration (UF) to form a one-step sRBF-UF system. This naturalness-artificiality combination could realize stable contaminants removal and trans-membrane pressure (TMP) increase relief for over 30 days without dosing chemicals. Generally, both sRBF and UF played the important role in river water purification, and the interaction between them made the one-step sRBF-UF superior in long-term operation. The sRBF could efficiently remove contaminants (90 % turbidity, 60 % total nitrogen, 30 % ammonia nitrogen, and 25 % total organic carbon) and reduce the membrane fouling potential of river water under its optimum operation conditions, i.e., a hydraulic retention time of 48 h, an operation temperature of 20 °C, and a synergistic filter material of aquifer and riverbank soil. Synergistic adsorption, interception, and microbial biodegradation were proved to be the mechanisms of contaminants and foulants removal for sRBF. The sequential UF also participated in the reduction of impurities and especially played a role in intercepting microbial metabolism products and possibly leaked microorganisms from sRBF, assuring the safety of product water. To date, the one-step sRBF-UF was a new attempt to combine a natural process with an artificial one, and realized a good and stable product quality in long-term operation without doing industrial chemicals, which made it a promised alternative for water purification for cities alongside the river.

A Comprehensive Review of Performance of Polyacrylonitrile-Based Membranes for Forward Osmosis Water Separation and Purification Process.

Polyacrylonitrile (PAN), with its unique chemical, electrical, mechanical, and thermal properties, has become a crucial acrylic polymer for the industry. This polymer has been widely used to fabricate ultrafiltration, nanofiltration, and reverse osmosis membranes for water treatment applications. However, it recently started to be used to fabricate thin-film composite (TFC) and fiber-based forward osmosis (FO) membranes at a lab scale. Phase inversion and electrospinning methods were the most utilized techniques to fabricate PAN-based FO membranes. The PAN substrate layer could function as a good support layer to create TFC and fiber membranes with excellent performance under FO process conditions by selecting the proper modification techniques. The various modification techniques used to enhance PAN-based FO performance include interfacial polymerization, layer-by-layer assembly, simple coating, and incorporating nanofillers. Thus, the fabrication and modification techniques of PAN-based porous FO membranes have been highlighted in this work. Also, the performance of these FO membranes was investigated. Finally, perspectives and potential directions for further study on PAN-based FO membranes are presented in light of the developments in this area. This review is expected to aid the scientific community in creating novel effective porous FO polymeric membranes based on PAN polymer for various water and wastewater treatment applications.

PENGGUNAAN BIJI KELOR (Moringa oleifera L.) DAN BIJI ASAM JAWA (Tamarindus indica L.) PADA PENJERNIHAN AIR SUMUR BOR MELALUI PROSES KOAGULASI DAN FLOKULASI DENGAN METODE SENTRIFUGASI

Drilled well water at the Ar-Rahmat Mosque in Manunggal Village, Labuhan Deli District, Regency Deli Serdang, North Sumatra Province, has a color that tends to be yellow and cloudy. From the test results, it was found that the turbidity level in the drilled well water reached 35.3 NTU and the iron (Fe) content reached 1.679 mg/L. This shows that the borehole water does not meet clean water standards according to PERMENKES RI No.32 of 2017, namely with a maximum turbidity level of 25 NTU and a maximum iron (Fe) content of 1.0 mg/L. There is one way to purify borehole water by using moringa seeds and tamarind seeds in the coagulation and flocculation processes through the centrifugation method. This study aims to determine the most optimal seed composition in purifying well water. The mass variations used in this study were moringa seeds and tamarind seeds each with a mass of 0.08 grams and 0.09 grams. In this study, the results of the most optimal seed composition for purifying borehole water were tamarind seeds at a mass variation of 0.08 gram with a turbidity value of 0.53 NTU and a value of iron (Fe) content of 0.0087 mg/L. This shows that the drilled well water that has gone through the water purification process meets the PERMENKES RI standard No. 32 of 2017.

Comparative analysis of synthesis of GO, CoFe2O4 and CoFe2O4 coated GO and its removal efficiency of arsenic present in the solution

A collective process of water purification is designed to reduce or remove the existing water contaminants to make water more applicable. Nanotechnology is considered to be very effective in providing contaminants free water for use. Demand of inexpensive and effective adsorbents is increasing regularly in response to the immeasurable health effects of arsenic exposure through water. The present study covers the procedure of synthesis of Graphene oxide (GO), Cobalt ferrite (CoFe2O4) and CoFe2O4 coated Graphene oxide (GO-CoFe2O4). This study shows that in room temperature at pH of 7, adsorbent dose of 0.4 gm/lit, contact time of 15 min and initial arsenic concentration of 0.2 mg/lit in the solution can be removed with nanoadsorbents with efficiency about 19 % by GO, 79 % by CoFe2O4 and 85 % by GO-CoFe2O4 without considering any other parameters. But efficiency of arsenic adsorption of the prepared nanoadsorbents increased with pre oxidation and increased contact time. Arsenic adsorption efficiency of 40 % using GO, 97 % using CoFe2O4 and 97.5 % using GO-CoFe2O4 has been achieved with pre oxidation and 22 hrs of contact time at pH of 7, adsorbent dose of 0.4 gm/lit, and initial arsenic concentration of 0.2 mg/lit. Based on result obtained, it is established that CoFe2O4 coated GO can be an effective nanoadsorbents for arsenic removal from the solution. This result underlines the need of further study for field application of these nanoadsorbents.

Identifying the features of surface roughness and H2 bubble production on the super-hydrophobic properties of Al2O3 and Mg membranes

This research investigates Alumina (Al2O3) and Magnesium nano membrane layers using hybrid technology. Hybrid is a concept of combining two or more materials/elements to achieve something better. Hybrid technology was developed because of the possibility of combining materials/elements which, if used simultaneously, has more advantages than if used independently. The problem to be solved is to find the best composition of Alumina and Magnesium hybrid membranes. Superhydrophobic properties of the membrane are achieved at a percentage of Mg: 50 %, Al2O3:50 %. At a composition below 50 % Mg, the small surface roughness has a low surface tension, while the H2 production reaction by Mg is also low, so the surface tension carrying capacity of the gas and the roughness of the droplets is not strong, which causes the hydrophobicity to be low. In compositions above 50 % Mg, H2 production by high Mg makes bubbles cover the roughness peaks so that the surface tension is lower and changes the superhydrophobic to hydrophobic properties. At a high Mg percentage, H2 production is very large, while surface roughness decreases due to minimal Al2O3. As a result, the roughness grooves are unable to accommodate H2 gas bubbles, the bubbles completely cover the roughness peaks which are the source of surface tension so that the hydrophobic properties become hydrophilic. The results of this best hybrid composition can be used as a guide in making superhydrophobic membranes on Alumina (Al2O3) and Magnesium alloys. This membrane application is used as a filtration membrane in the water purification process. Superhydrophobic membranes are widely applied in membrane distillation, membrane gas absorption and pervaporation

Prediction of algal bloom using a combination of sparse modeling and a machine learning algorithm: Automatic relevance determination and support vector machine

Algae can produce odor substances and toxins that make the smell and taste of water unpleasant and impair the quality of human and aquatic life. Appropriate countermeasures can be implemented in advance in water purification processes to prevent algal disorders if the occurrence of algal blooms is accurately predicted. Several models have been developed to predict algal blooms. However, a comprehensive model that can be universally applied under various conditions is lacking. In this study, automatic relevance determination, a sparse modeling algorithm, and support vector machine were combined to construct prediction models for algal blooms in four Japanese dam reservoirs to predict their occurrence over 7 days. Automatic relevance determination was applied to a dataset consisting of monthly water quality data and daily hydraulic and meteorological data to identify variables relevant to the concentrations of Microcystis spp. and Dolichospermum spp., which are bloom-forming cyanobacteria and are dominant in freshwater ecosystems. A dataset of selected variables was used to train and validate the support vector machine models. The results of variable selection by automatic relevance determination revealed that the average concentration of total nitrogen in the past year and the average maximum temperature in the past 7 days may have an association with the algal concentration. Support vector machine models resulted in 92.3% accuracy and 86.4% precision for Microcystis spp. and 71.4% accuracy and 77.5% precision for Dolichospermum spp. on average in binary classification. The competitive relationship between Microcystis spp. and Dolichospermum spp., which differs according to the nutrient level and temperature, probably affects the prediction performance of the models. Our study suggests that the combination of sparse modeling and machine learning is applicable to the construction of a prediction model for site-specific algal bloom events in dam reservoirs.

Control of cyanobacterial bloom and purification of bloom-laden water by sequential electro-oxidation and electro-oxidation-coagulation

The outbreaks of cyanobacterial blooms have caused severe threat to aquatic ecosystem and public health. In this work, electrochemical technology with RuO2/IrO2/Ti (RIT) or/and Al as anode for cyanobacterial bloom control and simultaneous water purification were studied. Compared with RIT-Al and Al electrodes, RIT exhibited the highest effects on bloom algae inactivation and inhibition of algae regrowth. Live/dead analysis, SEM, intracellular reactive oxygen species (ROS) and antioxidant system activities revealed that RIT could disintegrate bloom flocs and damage embedded algal cells due to high intensity of oxidation. With the lysis of cyanobacterial bloom, high content of intracellular compounds containing organic carbon, nitrogen and phosphorus released, necessitating water quality restoration. In the subsequent water purification process, RIT-Al overtook RIT and Al in removal of organic and nutrient pollutants due to the complex effects of electro-oxidation, coagulation, co-precipitation, electro-nitrification and electro-denitrification. Therefore, sequential electro-oxidation and electro-oxidation-coagulation process was an effective method for control cyanobacteria bloom and simultaneous removal of DOM, microcystin-LR (MC-LR), nitrogen and phosphorus, which is a promising technology.