Water Treatment Unit Research Articles

Qualitative evaluation and corrective planning for centrifugal pump maintenance at Soekarno-Hatta airport

This study focuses on enhancing the maintenance processes of centrifugal pumps at Soekarno-Hatta Airport’s Water Treatment Unit in Indonesia, crucial for meeting the clean water needs of the airport, which served around 19.8 million passengers in 2022. Using a qualitative methodology, the research involved focus group discussions with the unit’s operators, technicians, and engineers to pinpoint maintenance challenges and devise solutions. Key findings reveal issues such as insufficient routine maintenance, unplanned repairs, and inadequate staffing, leading to operational disruptions and pump failures. The study highlights the role of Total Productive Maintenance (TPM) in reducing machine breakdowns and improving efficiency. It emphasizes the critical role of centrifugal pumps in the airport’s water supply system. The research proposes several corrective measures, adhering to the 5W + 1H framework, including regular lubrication, bearing replacements, hiring more staff, and advanced training on PLC systems. These actions aim to rectify immediate maintenance problems and establish a foundation for the long-term effectiveness of the pump systems. Conclusively, the study underscores the need for a comprehensive maintenance strategy that aligns with standard operating procedures and preventive maintenance. This approach is essential for boosting the operational performance and reliability of the Water Treatment Unit. It has broader implications for similar infrastructure facilities, underscoring the importance of efficient maintenance management.

Inisiasi Pengolahan Air Embung dengan Teknologi Multimedia Filter (MMF) sebagai Solusi Air Bersih di Kabupaten Bojonegoro

Clean water and proper sanitation are fundamental human needs. Nganti Village, located in Ngraho Subdistrict, Bojonegoro Regency, faces significant drought and clean water shortages, particularly during the dry season. The water quality remains subpar despite the presence of springs and water reservoirs. Consequently, processing raw water from the village's reservoir can offer a viable solution. This service activity aims to harness water reservoirs as a clean water source through multimedia filter (MMF) technology. The activities, conducted from 2022 to the end of 2023, encompass four stages: socializing the program plans, constructing multimedia filters (MMF), installing the water treatment unit on-site, and evaluating water quality, followed by necessary follow-ups. The primary activities involve installing water treatment units with MMF technology in collaboration with village officials and the community. The treated water is then tested for quality at the IPB University laboratory. Test results indicate that MMF technology significantly improves water quality, reducing parameters such as Magnesium, Manganese, Calcium, Iron, and Phosphate by 25.8‒97.8%, thus meeting quality standards. However, some parameters, such as TSS, COD, and Zinc, still exceed quality standards, necessitating further processing. This advanced water treatment requires involvement from the local government, particularly in funding through community empowerment programs, to install advanced treatment units and provide operational support for these units.

Physico-chemical and microbiological parameters of natural, industrial recycled water and its treatment

Background: Under conditions of anthropogenic impact, the chemical composition of water in surface rivers and groundwater bodies is subjected to pollution, which leads not only to a decrease in water quality, but also to an increase in the number of pathogenic and opportunistic bacteria. Aim: The purpose of this work is to study the physicochemical and microbiological parameters of natural and industrial recycled water before and after treatment with coagulants based on activated aluminum alloys. Materials and methods: As natural waters were analyzed: natural waters from water intake “Almaty SU”, “Medeu” tract, Zhaiyk river, from the well of experimental metallurgical production of IMOB. As recycled water was analyzed water taken from the water treatment unit of deep oil refining production. Turbidity was measured using HACH 2100Q turbidimeter and 2100Qis turbidimeter (USA). Cell morphology of microorganism cultures was studied by light microscopy using a MicroOptix MX-1150 (T) stereoscopic-sotrinocular microscope. Results: An effective and technologically simple method of obtaining aluminum polyoxychloride with the content of the main substance from 33 to 41.0% by Al2O3 and basicity from 55.1 to 66.5% has been developed. The method consists in dissolution of aluminum alloy activated by metal-activators (indium, gallium, tin) in the amount of 0.5–1.0 wt.% of each in 3% HCl. Physico-chemical and microbiological parameters of natural and industrial recycled water have been studied. The efficiency of the obtained aluminum polyoxychloride for treatment and conditioning of drinking water and industrial recycled water was evaluated. Conclusion: Unique alloys with high energy characteristics based on aluminum containing indium, gallium, tin from 0.5–1.0 wt.% have been created. The alloy has high activity in various oxidizing media (water, hydrochloric acid). A technologically simple method of obtaining aluminum polyoxychloride has been developed. Chemical and microbiological composition of natural and industrial recycled water has been studied. Coagulants based on activated aluminum alloys are effective in the processes of conditioning and purification of natural and recycled water from toxic compounds, have bactericidal activity, the level of gram-negative bacteria is reduced to 73%, gram-positive bacteria to 84% and to 96% of other groups of microorganisms. Fungi and yeasts (Mucor, Fusarium) were not detected after water treatment. Efficiency of water turbidity reduction reaches 90–99%, permanganate oxidizability up to 93%.

Minimizing brine waste in thermal power plants: A techno-economic evaluation of secondary RO and closed circuit RO systems

Thermal power plants situated in water-scarce regions encounter a critical challenge: balancing high water demand with environmental sustainability. Although efforts have been concentrated on optimizing cooling systems, the aspect of minimizing wastewater within water treatment units (WTUs) has been overlooked. This study conducted a techno-economic analysis comparing two brine treatment options for WTUs, secondary reverse osmosis (RO) and closed-circuit RO (CCRO), using a power plant in northwestern Iran as a case study. Both systems demonstrated notable water conservation benefits. CCRO achieved a 10 % higher recovery rate but necessitated 12 % more antiscalant. The secondary RO system consumed 56 % more energy than CCRO (1.68 vs. 1.078 kWh per m3) and emitted 20.5 % more greenhouse gases. Despite CCRO having a 35 % higher initial cost, its superior recovery rate resulted in a comparable total product cost of permeate water (approximately $0.55 per m3). This attributed to CCRO's reduced energy consumption (56 % less) and operational costs (20 % less), which offset its higher capital expenses. The study also emphasized the significance of a system's lifespan and interest rates as the most critical factors influencing total product cost. Operational costs, including labor, antiscalant, and electricity, also played a role, albeit to a lesser extent. These findings indicate that CCRO technology presents a promising environmentally sustainable solution for power plants aiming to reduce wastewater generation and enhance water management strategies.

Processable CMP aerogel with Ag nanocatalysts for the treatment of combined pollutant containing p-NP&MO in continuous flow

It is challenging to produce soft polymer materials with high surface area and nanoscale morphology that can be used for continuous flow water treatment in a processable, versatile, and stable manner. Here, we manufactured a processable Ag@CMPA-bph and used it to treat pollutants in wastewater at continuous flow conditions. The aerogel was prepared by a simple reduction method of CMP matrix and Ag metal precursors. Thermogravimetric analysis and electron microscopy showed that the aerogel had excellent thermal stability and distribution of fine Ag nanoparticles. The synthesized aerogel inherits the controllable properties of the CMP matrix and can be tailored to a specific shape for installation into the water treatment unit. In continuous flow conditions, this aerogel shows excellent catalytic activity to efficiently treat the combined pollutant containing p-nitrophenol and methyl orange (p-NP&MO), which can reach a removal rate of more than 99 % at the flow rate of 0.6 L h-1. Furthermore, the Ag@CMPA-bph can also be used for continuous flow treatment of pollutants in river water sample and shows robust anti-pollution load capacity and catalytic activity.

An optimal standalone wind-photovoltaic power plant system for green hydrogen generation: Case study for hydrogen refueling station

Sustainability goals include the utilization of renewable energy resources to supply the energy needs in addition to wastewater treatment to satisfy the water demand. Moreover, hydrogen has become a promising energy carrier and green fuel to decarbonize the industrial and transportation sectors. In this context, this research investigates a wind-photovoltaic power plant to produce green hydrogen for hydrogen refueling station and to operate an electrocoagulation water treatment unit in Ostrava, Czech Republic's northeast region. The study conducts a techno-economic analysis through HOMER Pro® software for optimal sizing of the power station components and to investigate the economic indices of the plant. The power station employs photovoltaic panels and wind turbines to supply the required electricity for electrolyzers and electrocoagulation reactors. As an off-grid system, lead acid batteries are utilized to store the surplus electricity. Wind speed and solar irradiation are the key role site dependent parameters that determine the cost of hydrogen, electricity, and wastewater treatment. The simulated model considers the capital, operating, and replacement costs for system components. In the proposed system, 240 kg of hydrogen as well as 720 kWh electrical energy are daily required for the hydrogen refueling station and the electrocoagulation unit, respectively. Accordingly, the power station annually generates 6,997,990 kWh of electrical energy in addition to 85595 kg of green hydrogen. Based on the economic analysis, the project's NPC is determined to be €5.49 M and the levelized cost of Hydrogen (LCH) is 2.89 €/kg excluding compressor unit costs. This value proves the effectiveness of this power system, which encourages the utilization of green hydrogen for fuel-cell electric vehicles (FCVs). Furthermore, emerging electrocoagulation studies produce hydrogen through wastewater treatment, increasing hydrogen production and lowering LCH. Therefore, this study is able to provide practicable methodology support for optimal sizing of the power station components, which is beneficial for industrialization and economic development as well as transition toward sustainability and autonomous energy systems.

Determination of technogenic risks when using various water purification technologies

In modern conditions, ensuring the reliability and safety of water supply systems is a primary task for the industrial economy and the safety of life of the population of Ukraine. Constant bombing and damage to critical infrastructure facilities, including water management facilities, endangers the stability and quality of the country's water resources. In this context, conducting research on the identification of man-made risks in water treatment systems using various technologies, as well as developing strategies to increase the reliability and safety of operation of water supply systems are becoming relevant for the industrial sector of Ukraine. In order to increase the reliability of water treatment units and their operational safety, man-made risks were investigated when using ion exchange, electrodialysis, and water distillation technologies at thermal power plants. It is shown that during normal operation of the ion-exchange water purification system with an average productivity of 400 m3/h, in the case of frequent changes in the concentration of salts at the inlet, the risk of receiving underpurified water is 0.0783. This value must be taken into account for the assessment of economic and social-ecological risks, since it exceeds the generally accepted value of 0.01. When using electrodialysis water purification and frequent changes in the concentration of salts at the inlet, the risk of receiving underpurified water is 0.0271. This value is also greater than 0.01 risk accepted as acceptable. The water distillation technology has enough margin to compensate for any deviations in the purification process and gives a very low risk. However, the distillation process is more effective in removing only soluble impurities, while in the case of suspended substances, in particular of organic origin, there is a risk of exceeding the limit of 0.01.

Cooling Tower Performance Efficiency in Water Treatment Unit at PT. X Sukowati

Cooling Tower Performance Efficiency in Water Treatment Unit at PT. X Sukowati

Performance of Rapid Sand Filter Dual Media for Microplastic Removal in the Water: The Effect of Microplastic Size and Effective Size of Filter Media

Microplastics (MPs) significantly damage the environment and human health, leading to a growing global concern. MPs have been detected not only in the natural environment but also in the drinking water treatment process. One of the configurations of the drinking water treatment unit is filtration. Only a few research studies have been published on microplastic removal in the water system. This study was conducted to determine the performance of a rapid sand filter (RSF) in removing microplastics in water with a variation in the effective size (ES) of silica sand and microplastic size. In this study, microplastics are artificially made with size variations of < 400 μm and >400 μm. The filtering uses two variations in the adequate size (ES) of silica sand, namely 0.4 mm and 0.7 mm. At the same time, anthracite is only a control variable with ES = 0.69 with a flow speed of 4 m / h and an observation time of 30, 60, 90, and 120 minutes. The results show that the filter media ES 0.4 has the highest efficiency values of 91.30% for the microplastic size MPs <400 µm and 95.80 % for the larger microplastic >400 µm. In addition, the average percentage removal of ES 0.7 mm was 77.24 % for the size of MPs <400 µm and 95.77% for the size of Mps >400 µm. Gaining insight into the mechanisms involved in removing microplastics from drinking water is essential for developing more effective techniques for eliminating them.

Helically Coiled Tube Flocculators in Water Clarification Systems: Optimal Length Evaluation and Process Efficiency Probabilistic Analysis

New sustainable technologies have been explored as potential solutions to address the global issue of water scarcity by enhancing water treatment processes. In this context, an innovative coagulation/flocculation unit known as the helically coiled tube flocculator (HCTF) has emerged, offering notable advantages such as high process efficiency, short detention time, and cost-effectiveness compared to conventional hydraulic units. The HCTF harnesses its flow energy to disperse coagulation/flocculation agents and facilitate the formation of flocs through collisions between destabilized particles. This paper introduces an assessment of the process efficiency, geometric properties, and hydraulic characteristics of an alternative and sustainable water clarification system incorporating an HCTF, with the aim of determining its optimal length. In HCTFs, the flocculator’s length (referred to as L) can exert a significant influence on process efficiency, necessitating a comprehensive evaluation of this parameter for the rational design of such units. To accomplish this, the paper scrutinizes physical experimental findings from previous research articles, which are related to the efficiency of flocculation (indirectly estimated by analyzing turbidity removal efficiency). Additionally, it examines the geometric and hydraulic attributes across 48 distinct variations of HCTFs. This study culminates in the development of a model for determining the optimal length for HCTFs. Furthermore, it includes a probabilistic assessment that establishes a connection between the optimal length and other parameters involved in the clarification process—whether deterministic or probabilistic—and their impact on the final process efficiency, all with a 90% confidence level. This paper stands out by pioneering the determination of the optimal length of HCTFs, filling a gap in the existing literature, which previously only mentioned the importance of this parameter in process efficiency without providing a predictive model. The results highlight the robustness of the proposed alternative clarification system. Even in scenarios with substantial variations in dimensional hydraulic parameters (such as a worst-case relative standard deviation of 20%), the process efficiency fluctuations range between 1.3% and 5.2%. These outcomes lend support to the adoption of such alternative water clarification systems. They also underscore the potential of probabilistic evaluation as a valuable tool for investigating novel water and wastewater treatment units and enhancing existing ones.

Использование преобразованного уравнения электронейтральности при проведении технологических расчетов водоподготовки на ТЭС и АЭС

When performing technological calculations of water treatment units for thermal power plants (TPP) and nuclear power plants (NPP), it is necessary to determine the quality indicators of process water after the processing steps. The main difficulty is to calculate the concentrations of weak electrolytes since they are in chemical equilibrium with all forms of dissipation. Currently, for each type of processing, either simplified models or methods that solve a complex computational problem are used for calculations. It is necessary to develop a universal mathematical model that allows high accuracy to calculate the concentrations of weak electrolytes and the pH value for various types of water treatment. To develop the model the authors have applied the method of mathematical modeling of chemical-technological processes at thermal power plants and nuclear power plants. A mathematical model based on the transformed equation of electrical neutrality is proposed. It can be used to determine the equilibrium concentrations of dissociation forms of weak electrolytes (primarily water itself and carbonic acid) after various stages of water treatment. The proposed model allows, when conducting technological calculations of water treatment plants, to more accurately and universally calculate the concentrations of weak electrolytes and determine the pH value in process waters for various types of water treatment. The model can be used to determine the required doses of chemical reagents to ensure the required values of technological indicators (pH and Langelier index) in treated water.

Development of AI-based process controller of sour water treatment unit using deep reinforcement learning

BackgroundDue to the variability in the feedstock conditions and the nonlinearity of the sour water stripping process, determining the optimal operating conditions for Sour Water Treatment Unit (SWTU) is a huge challenge. MethodsIn this study, we propose an AI-Based Process Controller (AIPC) for optimizing the SWTU, combining deep reinforcement learning (DRL) and expert knowledge. A surrogate model of an industrial SWTU digital twin was developed to serve as the environment for DRL. A reward function was designed and compared with others for evaluation. A method for seamless switching was devised to guarantee uninterrupted device operation by preventing any interference from the policy network. Significant FindingsIn contrast to the alternative control schemes, the AIPC not only demonstrates superior performance in mitigating overshooting and enhancing setpoint tracking precision but achieves a reduction in stripping steam usage. The proposed method has great potential in the field of real-time optimization.

Study on Conventional Drinking Water Treatment for Removing Emerging Contaminants: A Literature Review

Emerging contaminants (ECs) are substances that can be synthetic or natural, or even microorganisms that are usually not monitored in the environment and could be harmful to the environment and human health. These chemicals can include pharmaceuticals, such as ibuprofen and acetaminophen, and industrial chemicals, e.g., perfluorooctanoic acid (PFOA). Common conventional drinking water treatment plants (CDWTP) are not designed to remove emerging contaminants, so these compounds can enter the water system and affect the drinking water treatment process. This study aims to focus on the performance of CDWTP in removing ibuprofen, acetaminophen, and PFOA parameters, as well as determine suitable water treatment units to eliminate these parameters from the system. An extensive literature review was conducted and further analysed using descriptive and qualitative analysis to understand the unit performance in removing emerging contaminants, followed by the simple simulation to determine the types of advanced drinking water treatment facilities that perform better in eliminating ECs. The results show that CDWTP could reduce ibuprofen concentration in water with 40%, 20%, and 36% efficiency through coagulation-flocculation, sand filtration, and disinfection, respectively. Acetaminophen removal is up to 67%, 51%, and 66.45% during coagulation-flocculation, sand filtration, and disinfection, respectively. However, PFOA removal is only up to 5%, 7%, and 2% during coagulation-flocculation, sand filtration, and disinfection, respectively. Membrane treatment technology with reverse osmosis could remove ibuprofen, acetaminophen, and PFOA compounds more effectively with removal efficiencies of 99.99%, 96%, and 100%, respectively.

Tubular and bio-based carbons as binder-free gas diffusion electrodes for heterogeneous electro-Fenton to remove micropollutants

Heterogeneous electro-Fenton (HEF) coupled with anodic oxidation offers a plug-and-treat and chemical-free process over a wide range of pH values for removing recalcitrant micropollutants (MPs). This work introduces a self-standing and Fe-containing tubular carbon as a gas diffusion electrode (GDE) for HEF. Unlike planar Fe-containing carbon electrodes, as-synthesized carbons contain no fluorinated polymer as a subgroup of perfluoroalkyl and polyfluoroalkyl substances (PFAS), omitting the risk of secondary pollution due to undesired PFAS release during electrolysis. The implementation of GDE enables the increase of current densities up to 25mAcm−2, approaching relevant conditions for real-life applications. The altering pore structure on the gas channel side illustrates the possibility of minimizing GDE flooding without using hydrophobic and fluorinated polymers. GDEs without catalyst shows a specific H2O2 production rate of 3.6mgcm−2h−1 with a current efficiency of 56% at an applied current density of 8.5mAcm−2. Additionally, the Fe-containing GDE removes sulfamethoxazole (SMX) and carbamazepine (CBZ), revealing a declined degradation rate in a mixture, especially for a more recalcitrant pollutant such as CBZ. This work reveals the potential of as-synthesized self-standing tubular GDEs as PFAS-free electrodes for a decentralized and modular water treatment unit.

Pemanfaatan Tandan Kosong Kelapa Sawit (Tkks) Sebagai Arang Aktif Untuk Penjernihan Air di Desa Muara Sebapo Kecamatan Mestong Kabupaten Muaro Jambi

The need for clean water in Muara Sebapo Village remains a serious issue to this day. The water obtained by the community from dug wells or boreholes often appears yellow and has an unpleasant odor. This water typically has a high concentration of Fe3+ ions, causing the water to turn yellow and become odorous. On the other hand, Muara Sebapo Village has extensive oil palm plantations, which generate solid waste in the form of Empty Palm Fruit Bunches (EFB). Until now, this waste has been underutilized, and in some cases, it has been disposed of or burned. Therefore, efforts are needed to address this issue so that the community can access clean water and utilize waste wisely. In this program, outreach and education are conducted on how to treat well water using solid waste EFB effectively. EFB waste can be transformed into activated carbon, which can be used as a water purification medium in a water treatment unit in the plantation areas and the surrounding community. Activated carbon will act as an adsorbent capable of adsorbing metal ions and organic pollutants present in well water.

Penentuan Kebutuhan Poli Aluminium Klorida pada Proses Penjernihan Air di Unit Water Treatment PT. XYZ Kuala Tanjung

A Water Treatment Unit (WTU) is a station that works on the processing and conditioning of raw water to meet the desired water quality. Water purification at PT. XYZ Kuala Tanjung uses raw water sourced from surface water or rivers. The river water used still contains solid substances and organic matter that render the water unsuitable for industrial use. Both suspended and colloidal solid substances can cause turbidity. Turbidity caused by solid substances can be addressed using coagulation techniques. The purpose of this research is to determine the optimal concentration and dosage of coagulant to clarify water in the WTU. The coagulant used is polyaluminum chloride (PAC). The research method is based on experiments using jar tests and stoichiometric calculations. The determination of the optimal coagulant is measured based on turbidity parameters. Experiments are conducted with varying concentrations of PAC ranging from 25-65 ppm, and the smallest turbidity value obtained is 1.21 NTU at a PAC concentration of 65 ppm, with a PAC requirement of 202.6679 kg/day. The higher the PAC concentration, the clearer the resulting water, but the daily requirement for PAC also increases.

Optimizing dialysis water treatment based on medical planning requirements

This paper introduces a new approach to improving hemodialysis and peritoneal dialysis processes. This maintains compatibility between the water treatment unit and active dialysis machines. Identification of different deviations in the patient’s requirements to classify the suitable flow rate (FR) of the pure water can be created through an Adaptive Neuro-Fuzzy Inference System (ANFIS). Four types of categories are classified: quarter load, half load, three-quarter load, and full load. This includes two main steps: identifying the dialysis categories with patients and measuring the suitable FR for each category. The effective FR of water was computed to indicate how the number of pumps rose as the number of patients treated within the dialysis unit increased. The introduced prediction method was tested against artificial neural networks to predict alum doses (ANN-AD) method, artificial intelligence as a combinatorial optimization strategy (AN-COS) using peach-palm waste in a solid-state fermentation environment, expert system applications (ESA) in chronic kidney disease management (MDSSs), prescription optimization for automated peritoneal dialysis (BCPH). In this work, pumping system parameter estimation was utilized to assess the performance of the introduced systems based on input voltage, input current, rotor speed, and electromagnetic torque waveforms of the pumping drive. This method uses the ANFIS algorithm to construct a high-performance pumping system to evaluate and predict the flow rate of dialysis machines based on input–output estimates. The flow rate values for each patient in critical care units can be controlled by the presented algorithm according to the time of dialysis. A good predictive model based on integrating the experience and decision making of medical planners was implemented. The proposed method not only improves accuracy but also saves time in the dialysis unit. The presented fuzzy classifier uses the ratio of the number of predicted true positives and false positives to the total number of anticipated positives. The simulation results show that the proposed technique can be successfully used to classify the suitable FR of the water according to the hemodialysis load. One of the advantages of the presented technique is the ability to predict the value of FR in real time with reliability, low computational complexity, and a high accuracy of 98.01%, which simplifies the dialysis process for many patients while at the same time leading to improved performance of hemodialysis. The presented method can be implanted in online FR estimation and analysis hardware for hemodialysis, is easy to calculate and run in real time, minimizes hemodialysis costs, and saves run time.

Performance of Waste Water Treatment Plans in Hospitals : Literature Review

Introduction: Hospitalrecyclingwhich cannot function normally and there are calculation errors in thewater mass balanceTo minimize the impact of waste water on environmental pollution, an evaluation of the IPAL unit is carried out. The aim of this research is to evaluate the IPAL and provide suggestions related to optimizing wastewater treatment at Hospital to improve wastewater removal performance. Material and Methods: This study refers to design criteria and quality standards based on literature review with PICO Analysis and evaluation of existing conditions using secondary and primary data. Based on the results of the Wastewater Treatment Plant (WWTP) evaluation, it was found that the waste water discharge was 166.3 m3/day, had an efficiency that was in the very efficient and efficient category in processing waste water pollutant parameters so that the waste water treatment process ran well, and there was equalization of the first and second settling tanks. , activated sludge, trickling filter, filtration, disinfection and recycling did not meet the design criteria so recalculations were carried out.. Results: The solution provided is to tighten monitoring and testing of the condition of the quality of wastewater coming out of the WWTP unit by changing the sampling test method, re-measuring the quality of influent wastewater, improving the workings of the IPAL unit according to the applicable Standart Operation Procedure (SOP). Conclusion: After evaluating the waste water treatment unit, conclusions can be drawn, among others, based on the results of water quality tests and the work performance of the waste water quality parameters. The waste water quality parameter degradation efficiency is very effective, effective and quite effective and all parameters tested are in accordance with applicable quality standards.

Fate and potential risks of microplastic fibers and fragments in water and wastewater treatment processes

Water and wastewater treatment plants (WWTPs) receive various types of microplastics (MPs), with fibers and fragments being dominant shapes. Here we investigated the removal behavior and transformation of MPs (polypropylene and polyethylene terephthalate fibers and fragments) in simulated water and wastewater treatment units, including activated sludge process, coagulation, sand filtration, and advanced oxidation/disinfection. Sand filtration demonstrated the highest average efficiency in removing MPs (98 %), followed by activated sludge process (61 %) and coagulation (55 %), which was associated with their physicochemical properties (shape, size, density, surface functional groups, etc). In activated sludge process and coagulation, the polymer type had a greater impact on the removal of MPs than the particle shape, while in sand filtration, the particle shape played a more important role. When subjected to the long-term operation and backwashing of sand filters, approximately 15 % of the initially filtered fragments broke through the sand media, with nearly no fibers escaping. UV-based advanced oxidation and chlorination induced the leaching of dissolved organic matters with different molecular characteristics from fragment MPs, resulting in varying levels of cytotoxicity and bacterial toxicity. Our study provides important information for predicting the fate of MPs and mitigating their impacts in WWTPs.

Simulation Of Acidic Water Purification Process In Refinery Based On Determining Appropriate Operating Conditions

Acidic process water produced by refineries contains some hazardous pollutants such as (H2S and NH3). Acid water extraction units remove both compounds from the water. The removed contaminants are sent to a sulphur recovery unit to produce sulphur and avoid any acid emissions contrary to environmental regulations. Water pollution is a problem that concerns all people in the world. In view of the importance of preserving the environment and water resources, in this research, the simulation of the acid water treatment unit in the refinery was studied using the Aspen Hysys software based on determining the appropriate operating conditions. The NRTL electrolyte activity coefficient model was used to predict the system's thermodynamic behaviour. The simulation results showed that the suitable temperature for the feed entering the tower is about 38°C and the convenient distance for the trays in the disposal tower is 0.54 mm. Under these conditions, the concentration of hydrogen sulphide 0.1694 and 0.2418 of ammonia in the acid gas exiting the tower reaches its maximum at a molar flow rate of the mixture of about 39.86 kgmol/h, according to the economic considerations of the operating tower.