Product Water Quality Research Articles

Predictive performance and costing model for Membrane Capacitive Deionization (MCDI) at operational scale

A model that can be used to predict the performance of Membrane Capacitive Deionization (MCDI), including current efficiency, flowrate of the product water, water recovery and energy consumption is established in this work. The model was developed using a Response Surface Model approach that considers the influence of influent conductivity, flowrate passing by the electrodes and applied current on MCDI system performance rather than relying on electrochemical principles or the description of the intrinsic properties of the carbon electrodes and ion exchange membranes. In the scenarios tested here, flowrate contributes the most towards MCDI performance. The appropriateness of using NaCl for an MCDI performance model is confirmed. The model can be applied to extensive applications with two examples detailed here including a small town potable application of 100 m3/day with influent water of 2000 μS/cm and an industrial wastewater application of 1000 m3/day with influent water of 4000 μS/cm. A costing model is developed and applied to the two scenarios with the optimised levelized cost of water (LCOW) found to be US$0.74/m3 for the small town and US$1.08/m3 to US$1.41/m3 for the industrial wastewater (product water quality dependent). By maximising the production rate, the LCOW can be minimised. The model presented here can be applied to a wide range of applications or used as a framework for efficient performance modelling of other MCDI configurations.

Impact of Integration of FO Membranes into a Granular Biomass AnMBR for Water Reuse

The granular sludge based anaerobic membrane bioreactor (G-AnMBR) has gained emphasis in the last decade by combining AnMBR advantages (high quality permeate and biogas production towards energy positive treatment) and benefits of granular biomass (boosted biological activity and reduced membrane fouling). With the aim to further reduce energy costs, produce higher quality effluent for water reuse applications and improve system efficiency, a forward osmosis (FO) system was integrated into a 17 L G-AnMBR pilot. Plate and frame microfiltration modules were step by step replaced by submerged FO ones, synthetic wastewater was used as feed (chemical oxygen demand (COD) content 500 mg/L), with hydraulic retention time of 10 h and operated at 25 °C. The system was fed with granular biomass and after the acclimation period, operated neither with gas sparging nor relaxation at around 5 L.m-2.h-1 permeation flux during at least 10 days for each tested configuration. Process stability, impact of salinity on biomass, the produced water quality and organic matter removal efficiency were assessed and compared for the system working with 100% microfiltration (MF), 70% MF/30% FO, 50% MF/50% FO and 10% MF/90% FO, respectively. Increasing the FO share in the reactor led to salinity increase and to enhanced fouling propensity probably due to salinity shock on the active biomass, releasing extracellular polymeric substances (EPS) in the mixed liquor. However, above 90% COD degradation was observed for all configurations with a remaining COD content below 50 mg/L and below the detection limit for MF and FO permeates, respectively. FO membranes also proved to be less prone to fouling in comparison with MF ones. Complete salt mass balance demonstrated that major salinity increase in the reactor was due to reverse salt passage from the draw solution but also that salts from the feed solution could migrate to the draw solution. While FO membranes allow for full rejection and very high permeate purity, operation of G-AnMBR with FO membranes only is not recommended since MF presence acts as a purge and allows for reactor salinity stabilization.

Modelling of Acid Mine Drainage in Open Pit Lakes Using Sentinel-2 Time-Series: A Case Study from Lusatia, Germany

Strong acid mine drainage (AMD) processes in the flooded, formerly open pits in the Lusatia area present an enormous environmental challenge for the rehabilitation of the post-mining landscape. Extensive and costly monitoring is required for optimal AMD management and remediation planning and control. Because of the large size of the area and the dimension of the problem, the regular sampling can only provide limited point data, which needs to be extrapolated to the entire area. Consequently, the search for effective approaches for extrapolating the point data to the area of all water bodies is essential for rehabilitation success monitoring and for understanding the dependencies between AMD and environmental factors such as land use, weather conditions, geology, and hydrogeology. The main aim of this study was to investigate the suitability of Sentinel-2 multispectral imagery and artificial neural networks (ANNs) for the quantitative mapping of acid mine drainage (AMD) constituents, such as dissolved iron, pH value, and sulfate in large water bodies, for an area of approximately 7220 km2 (the area of the pit lakes is about 185 km2). Correlations between different chemical water parameters were also investigated. An extensive water monitoring dataset was used to train artificial neural networks for the identification of dependencies between the multispectral remote sensing data and the water quality ground measurements. Respective relationships have been identified, especially for dissolved iron and pH. These trained ANNs have been used to produce water quality maps with high spatial (10 × 10 m) and temporal (any cloud-free period) resolution, which show the wide variability of water quality in the different parts of the mining region. Concrete sources of AMD can be identified using the water quality maps of single lakes, and the success of sanitation measures such as liming was visualized. The approach opens many doors for the optimization of both the monitoring program and sanitation technology.

Design of a multistage hybrid desalination process for brine management and maximum water recovery.

Hypersaline brine production from desalination plants causes huge environmental stress due to the untenable conventional discharge strategies. Particularly, brine production is expected to drastically increase in the coming few decades due to the increasing desalination capacity in attempts of forestalling water scarcity. Thereby, zero liquid discharge (ZLD) is a worth-considering solution for strategic brine management. ZLD or minimal liquid discharge (MLD) systems provide maximum water recovery with least or zero liquid waste generation and valuable salt production. In this work, a theoretical design of ZLD/MLD system is proposed for reverse osmosis (RO) brine management. Different scenarios are investigated utilizing multistage freeze desalination (FD) and its hybridization with multistage direct contact membrane distillation (DCMD), and eutectic freeze crystallization (EFC) technologies. The design is based on the experimental assessment of the indirect FD process at different feed salinities, i.e., 2g/L to 155g/L. FD experiments showed that ice quality is reduced at greater crystallinity levels and initial concentration. Moreover, a computational fluid dynamics (CFD) model is utilized to assess the performance of DCMD. A single DCMD module could produce 53kg/(m2.h) of pure water operating with 69% thermal efficiency. Eventually, water recovery, water quality, as well as specific energy consumption (SEC) are evaluated for the whole system. Based on different configurations of the hybrid ZLD system, the proposed design can achieve water recovery between 40 and 93% with SEC range of 28-114 kWh/m3. Results also showed that the produced water quality exceeds drinkable water standards ( 500mg/L). This work has provided great evidence in the practicality of ZLD/MLD systems for sustainable brine management.

Optimizing produced water quality for enhancing oil recovery

Produced water is a complex mixture of organic and inorganic compounds. In this research paper, the output is not theoretical as the work is implemented in the field to bring the produced water generated from the pay zone into a desirable range. The produced water from the pay zone is challenging as well as plays a crucial role in the oil and gas industry. The produced water contains many impurities which are not desirable for injection into the well to bring them into a desirable range study of Physico-chemical parameters and biological parameters of the raw effluent has been done experimentally. The water produced was treated effectively under suitable methods and filters viz, coagulation and flocculation by optimizing dose as per requirement, and various filtration techniques like selective filtration, series filtration, and cerini filtration. The fluid compatibility test was carried out to determine the scale and corrosion and to check the permeability retention of the XZ formation to make treated effluent water fit for injection. The treatment design was implemented properly to achieve desirable parameters for a desirable range.

Impact of large-scale effects on mass transfer and concentration polarization in Reverse Osmosis membrane systems

We present well-resolved computational fluid dynamics simulations of a large-scale reverse osmosis membrane-spacer configuration (∼ 1 m). Our computational model solves the flow and transport equations with variable solute-dependent properties. We utilize a high resolution computational mesh to resolve all relevant length scales associated with spacer-induced mixing and thin concentration boundary layers. An important contribution of this work is the development of a modified mass-transfer correlation that accounts for the development of the concentration boundary layer along the channel. A set of 2D axisymmetric simulations were performed for a spiral wound module layer with varying cross-flow conditions and spacer diameters which indicate a significant entrance length effect for concentration profile development at lower flow rates while mixing effects dominate at higher flow rates. The mass-transfer correlations at higher flow rates compare well with published correlations while a surrogate model for Sherwood number was obtained that depends on an additional similarity variable that accounted for entrance length effects at lower flow rates. Finally, a large-scale membrane-spacer design relevant to high-pressure reverse osmosis is studied with a non-uniform arrangement of spacers, which indicate a substantial saving in pressure drop (∼ 40%) compared to traditional uniformly spaced pattern with minor variations (∼ 2%) in concentration polarization, product water quality (∼ 1%) and water recovery (∼ 7%) compared to a uniform spacer pattern.

Hot water-methane reservoirs at southwest foothills of Koryaksky volcano, Kamchatka

A conceptual model of the thermal and water recharge of the Ketkinsky geothermal field as a product of magma and water injection from the Koryaksky volcano located 24 km apart was proposed. A digital hydrogeological model of the Ketkinsky geothermal field was developed in the volume of 7 km x 5 km x 2.5 km (from the topographic surface), it includes the space drilled by exploration and production wells. The model is based on an analysis of 3D distributions of temperature, pressure, salinity and CH4 content, geometrization of productive faults and well productivity characteristics. The geofiltration space was zoned in the model with separation of deep and shallow productive geothermal reservoirs, the area of deep thermal fluid upflow in the SSE part of the model base and the area of hidden thermal water discharge at the ground surface.A natural state inversion iTOUGH2-EWASG simulation was performed to estimate the deep thermal water upflow and permeability of productive geothermal reservoirs. The deep thermal water upflow is estimated to be about 10 kg/s, the permeability is estimated to be 190 mD (shallow productive reservoir) and 35 mD (deep productive reservoir). Inverse iTOUGH2-EWASG modeling of the hydrodynamic operating history of 1989–2020 was used to estimate the compressibility of the productive geothermal reservoirs: the compressibility of the deep reservoir is estimated at 7.16E-10 Pa−1, the shallow reservoir at 4.14E-07 Pa−1. Direct iTOUGH2-EWASG modeling with the above parameters reproduces the history of salinity and temperature changes in production wells.Forecast modeling of existing producing wells #23, K6, K01, K5 operation for 25 years with application of submersible pumps at immersion depth of 70 m confirms the possibility of their sustainable operation with total flow rate not less than 14.2 kg/s, adding four producing wells may yield to 54.3 kg/s with retaining of produced water quality (temperature, gas content of CH4, salinity).The use of submersible pumps and reinjection can significantly increase the reserves of Ketkinsky field to 165–175 kg/s of 70–80 °C and 60–70 g/s of CH4. Additional increase in reserves may be obtained by drilling the already known thermal anomaly in the SSE sector of the field and in the SWW foothills of Koryaksky volcano.

An emerging pilot-scale electrodialysis system for desalination of SWNF permeate: Evaluating the role of typical factors

Electrodialysis (ED) is suitable for brackish water desalination due to its unique electro-demineralizing mechanism. However, the role of typical factors in pilot-scale ED desalination performance has not been illustrated systematically. In this study, a pilot-scale energy-efficient ED system was manufactured for the desalination of seawater nanofiltration permeate which could be considered as a typical brackish water, and its influencing mechanisms of typical factors were investigated in detail. The factors included ion exchange membrane (IEM) type, water recovery (WR), temperature, and feed concentration. The results show that the permselectivity of IEMs, which is related to the leakage of co-ions, played an important role in ED desalination performance. Furthermore, the salinity of produced water increased 3-fold times with the WR increasing from 53 % to 67 % due to the intensification of ionic back diffusion. Besides, the SEC increased 37.7 % with similar salt removal ratio when temperature increased from 7 to 29 °C, which is attributed to the changes of IEM structures and solution chemical properties. Finally, the fluctuation in the feed concentration had significant influence on produced water quality and SEC due to continuous operation mode. This study provides insights into, and guidance for, the large-scale BWED desalination process.

An electrospun transporter-assisted evaporator with antifouling water channels for solar-driven desalination and water purification

BackgroundInterfacial solar steam generation is a promising, energy-efficient, and environmentally friendly technology in water purification. Most studies currently focus on the design of various light absorbers and improvement of energy conversion efficiency. However, there are few reports about how to enhance evaporation performance and water quality of evaporators in the treatment of oily water and seawater. MethodsHerein, this work demonstrates an electrospun transporter-assisted evaporator with antifouling water channels for water purification and desalination. The graphene oxide/polyacrylonitrile (GO/PAN) nanofibrous membrane as the photothermal layer can convert solar energy into heat for the vaporization of water. By in-situ crosslinking zwitterionic gel on a porous PAN nanofibrous strip as the water channel, the water channel can achieve a superwetting surface, thereby enhancing hydrophilicity and underwater superoleophobicity. FindingsThe evaporator with the zwitterionic gel modified PAN (ZG-PAN) strip demonstrates the stable evaporation rate and prevented the adhesion of organic pollutants, meanwhile decreases the concentration of total organic carbon in the collected water. Additionally, anti-polyelectrolyte effect of the zwitterionic polymer reduces the salt deposition on the evaporation surface and maintains stable desalination performance. Our study provides an effective method to improve solar evaporation performance and product water quality during a long-term oily water or seawater treatment.

Performance model for reverse osmosis

To meet the increasing global demand for freshwater, seawater reverse osmosis (SWRO) has become a widely used technology to produce freshwater from seawater. A SWRO system consists of different components such as pumps, membranes, valves, and energy recovery devices. While it may be simple for process designers to understand the individual performance of each piece of equipment, the performance of an entire SWRO system can be complex and counter-intuitive. Furthermore, SWRO processes are energy-intensive; thus, to minimize the Specific Energy Consumption (SEC) of the process, it is of utmost importance that the performance of the system is monitored in real-time. Due to periodic changes in seawater quality and weather conditions, the operating parameters in a SWRO plant need continuous tweaking to minimize energy consumption and optimize the use of chemicals such that product water quality requirements are met. This calls for the need of a performance monitoring and optimization tool for SWRO. Since the advent of RO in 1950, such a system has never existed. Here, we present the first performance model for reverse osmosis (PMRO) for monitoring and optimizing the performance of SWRO assets;the developed model predicts the SEC of an operating SWRO plant with 93 % accuracy.

Production of high-quality drinking water from chillers and air conditioning units’ condensates using UV/GAC/MF/NF hybrid system

In hot and humid regions, like the Middle East nations, where access to drinking water is minimal, water recycling and purification are essential. In this work, high-quality drinking water was produced by treating the condensates obtained from the air conditioning units. A membrane-based hybrid system consisting of ultraviolet irradiation, granular activated carbon, microfiltration, and nanofiltration membranes (UV/GAC/MF/NF) was applied in series to minimize the NF membrane fouling and enhance the product water quality. The microbial, organic, and ionic species of the feed and the product water were analyzed, and the target was defined to maximize the permeate flux (JV) and minimize the concentration of the organic matter in the product water (CODP). The effects of trans-membrane pressure (TMP, 2–5 bar) and feed flow rate (QF, 340–510 L h−1) on the target parameters were investigated through the Taguchi design of experiments and the ANOVA method. The obtained results showed that at the optimum conditions, almost a complete reduction of TDS (>98.37%), of COD (>97.87%), of BOD5 (>96.04%), of the total and digestive coliforms (100%), and turbidity (91.06%) were achieved. Additionally, it was found that the TMP and the QF were the most influential parameters on JV and CODP, respectively. The product water analysis at different stage cuts showed that the hybrid system is capable of recovering more than 97% of the feed water while the TDS, BOD5, and turbidity of the product water are only 2.58 ppm, 2.62 mg. L−1, and 0.22 NTU, respectively.

A comparative study of community reverse osmosis and nanofiltration systems for total hardness removal in groundwater

In this research, the efficiency of reverse osmosis (RO) and nanofiltration (NF) treatment methods installed in the dry zone (Sri Lanka) were examined as a function of operation parameters, feed and product water quality, membrane type, user maintenance, and wastes handling. The quality of the feedwater varies as electrical conductivity (265–1329 mg/L), total hardness (97–318 mg/L as CaCO3) and fluoride (0.58–2.93 mg/L), often exceeding WHO or SLS tolerance limits. About 77% of the feedwater contains dissolved organic carbon (DOC) above 4.00 mg/L that requires control to avoid membrane fouling and other harmful effects. The salt rejection ratio, pressure flux and transmembrane pressure of the RO/NF membranes vary widely with the feedwater quality. The operation parameters of the membrane plants vary significantly; eight RO plants use low-pressure (0.5–1.0 MPa) similar to the NF pressure requirement, but they desalinate water at 95% salt rejection efficiency. Most RO membranes deviate (>50%) from the recommended transmembrane pressure and specific permeate flux values. However, such deviations are not observed in NF treatment plants. RO membranes remove solutes excessively, but post mineralization step is currently not practiced in the study area. The water recovery by the NF membranes is highest (>60%) compared to RO plants. The wastewater resulting from the NF plants is handled satisfactorily compared to RO-generated wastes. In the area examined, the salinity occurs due to water's permanent hardness. Therefore, NF membrane-based technology is suitable to desalinate groundwater in the dry zone (Sri Lanka).

PRODUCTION OF SHRIMP IN INTENSIVE AQUACULTURE SYSTEM OF VANAME SHRIMP (Litopenaeus vannamei) USING DIFFERENT CULTURAL SLUDGE MANAGEMENT METHODS

The main problem in intensive shrimp pond culture is a decrease in the quality of proper water during shrimp rearing and the emergence of disease. This problem resulted in decreased productivity of vaname shrimp. One of the efforts made is through the application of sludge management methods, with the aim of reducing the pile of sludge at the bottom of intensive ponds. Sludge management methods include the system, CRS (Close Resirculating System), Semi Close, and biofloc. The writing method used is literature study, for data analysis by comparing the average production data and water quality in each system. Sludge management in the CRS system, move the remaining organic material into the settling pond. In semi close system, remove sludge periodically through central draine. sludge management in the biofloc system, utilizing heterotopic bacteria to treat the remaining organic matter. The largest Average Daily Gain (ADG) is present in the bioflocked system at 0.16 g / day and the smallest in the semi close system at 0.11 g / day. Survival rate (SR) is the highest survival rate in the biofloc system with SR reaching 88%, and the lowest in the CRS system, namely 81%. The best Feed Convertion Ratio (FCR) in the biofloc system is that the FCR value reaches 1.26, the next is the CRS system with FCR 1.33, and in the semi-close system the FCR value reaches 1.93. The best sludge management system of the three systems is the biofloc system. The average daily water quality data of the three systems are still in optimal conditions, although the parameters of ammonia, nitrite, and nitrate are high, but at the survival rate of the shrimp the three systems are still above 80%.

Effect of Lowering the pH of Sodium Hypochlorite on Control of Pseudomonas aeruginosa in Maintenance of Pharmaceutical Water System

Drinking water or potable water is a common source for generation of purified water or demineralized water which is used for processing of medicinal products such as tablets, capsules, syrups, and nasal sprays. Before allowing for purification, it is manufacturer’s responsibility to ensure the microbial load control in the source water to get good quality product water and to avoid biofilm formation in waterlines. The current research involves the study of an effectiveness of sodium hypochlorite (NaOCl) at various concentrations of water pH on microbial control by following pour plate technique. The aim of this study was to examine the effect of lowering the pH on the recovery of Pseudomonas aeruginosa. Three groups were tested by challenging known population of P. aeruginosa by varying the pH of 5.0, 7.0 and 9.0. No significant difference was observed at pH 5.0 and 7.0 and the recovery increased when the pH increased at 9.0. Effective microbial control was obtained at neutral pH. The increase of pH resulted decrease of effectiveness of NaOCl.

HOT WATER SANITIZATION AND ITS IMPACT ON MICROBIAL BIOFILM CAUSING BACTERIA PSEUDOMONAS AERUGINOSA AND PSEUDOMONAS PUTIDA

Biofilms are the challenge in maintenance of pharmaceutical water system. Generation of purified water or demineralized water and maintaining quality attributes are the key requirements as this water used for processing of medicinal products like tablets, capsules, syrups, nasal sprays, injectables etc. Before allowing for purification, it is manufacturer’s responsibility to ensure the microbial load control in the source water to get good quality product water and to avoid biofilm formation in waterlines. Current research involves the study of an effectiveness of Hot water sanitization in control of Biofilm formation bacteria Pseudomonas aeruginosa. The aim of this study was to examine the effect of Hot water on bacterial growth by challenging known concentration of Biofilm causing bacteria Pseudomonas aeruginosa. The study conducted by selecting different temperatures like 50 °C, 70 °C and 90 °C for holding the sample for different time points. Biofilm formation of Pseudomonas aeruginosa and other species like Pseudomonas putida is common issue in water systems, by using of two biofilm strains, sanitization effectiveness of hot water were examined.

Engineering pressure retarded osmosis membrane bioreactor (PRO-MBR) for simultaneous water and energy recovery from municipal wastewater

Osmotic membrane bioreactors (OMBR) have gained increasing interest in wastewater treatment and reclamation due to their high product water quality and fouling resistance. However, high energy consumption (mostly by draw solution recovery) restricted the wider application of OMBR. Herein, we propose a novel pressure retarded osmosis membrane bioreactor (PRO-MBR) for improving the economic feasibility. In comparison with conventional FO-MBR, PRO-MBR exhibited similar excellent contaminants removal performance and comparable water flux. More importantly, a considerable amount of energy can be recovered by PRO-MBR (4.1 kWh/100 m2·d), as a result of which, 10.02% of the specific energy consumption (SEC) for water recovery was reduced as compared with FO-MBR (from 1.42 kWh/m3 to 1.28 kWh/m3). Membrane orientation largely determined the performance of PRO-MBR, higher power density was achieved in AL-DS orientation (peak value of 3.4 W/m2) than that in AL-FS orientation (peak value of 1.4 W/m2). However, PRO-MBR suffered more severe and complex membrane fouling when operated in AL-DS orientation, because the porous support layer was facing sludge mixed liquor. Further investigation revealed fouling was mostly reversible for PRO-MBR, it exhibited similar flux recoverability (92.4%) to that in FO-MBR (95.1%) after osmotic backwash. Nevertheless, flux decline due to membrane fouling is still a restricting factor to power generation of PRO-MBR, its power density was decreased by 38.2% in the first 60 min due to the formation of fouling. Overall, in perspective of technoeconomic feasibility, the PRO-MBR demonstrates better potential than FO-MBR in wastewater treatment and reclamation and deserves more research attention in the future.

Characterization of produced water and surrounding surface water in the Permian Basin, the United States

A thorough understanding of produced water (PW) quality is critical to advance the knowledge and tools for effective PW management, treatment, risk assessment, and feasibility for beneficial reuse outside the oil and gas industry. This study provides the first step to better understand PW quality to develop beneficial reuse programs that are protective of human health and the environment. In total, 46 PW samples from unconventional operations in the Permian Basin and ten surface water samples from the Pecos River in New Mexico were collected for quantitative target analyses of more than 300 constituents. Water quality analyses of Pecos River samples could provide context and baseline information for the potential discharge and reuse of treated PW in this area. Temporal PW and river water quality changes were monitored for eight months in 2020. PW samples had total dissolved solids (TDS) concentrations ranging from 100,800–201,500 mg/L. Various mineral salts, metals, oil and grease, volatile and semi-volatile organic compounds, radionuclides, ammonia, hydraulic fracturing additives, and per- and polyfluoroalkyl substances were detected at different concentrations. Chemical characterization of organic compounds found in Pecos River water showed no evidence of PW origin. Isometric log-ratio Na-Cl-Br analysis showed the salinity in the Pecos River samples appeared to be linked to an increase in natural shallow brine inputs. This study outlines baseline analytical information to advance PW research by describing PW and surrounding surface water quality in the Permian Basin that will assist in determining management strategies, treatment methods, potential beneficial reuse applications, and potential environmental impacts specific to intended beneficial use of treated PW.

Effect of supercritical CO2 flooding on the produced water quality and performance of the scale inhibitors in a typical tight sandstone oilfield

In order to enhance oil recovery, supercritical CO2 (scCO2) flooding has been applied in many oilfields to extract oil and gas post primary recovery. However, it causes serious scaling problems in the reservoir, oil well and production tubing. In this article, the produced water quality before and after scCO2 flooding in carbonate reservoirs are analyzed. The scaling trend of produced water before and after scCO2 flooding was calculated by using the Davis-stiff saturation index and Ryznar stability index methods. Static experiments and scanning electron microscope (SEM) are used to study the scale inhibition performance and mechanism of HEDP, ATMP, MA-AA, and PAA on CaCO3 in produced water before and after scCO2 flooding. The results show that after scCO2 flooding, the quality of produced water changes obviously, thus the scaling trend of produced water increases, the growth of CaCO3 crystal is affected and the scale inhibition efficiency of conventional scale inhibitors decreases.

Experimental Study on the Influence of Flexible Control on Key Parameters in Reverse Osmosis Desalination

Variable-frequency drive (VFD) has been widely used in reverse osmosis desalination. Our purpose is to study how the VFD and pressure regulating valve affect the key parameters of reverse osmosis desalination and their action principle through experiments. Firstly, the power frequency is controlled by VFD, and the operating pressure is controlled by pressure regulating valve (needle valve) in the experiment. The feed water passes through the multimedia filter, precision filter and permeable membrane channel in turn, and permeate water and brine enter the fresh water tank and the brine tank respectively. Secondly, through experiments on seawater and brackish water respectively, the water flow rate, product water quality, energy consumption and recovery rate under different operating pressures are obtained when the power frequency is 25, 30, 35, 40, 45, and 50 respectively. Finally, combined with the working principle and mathematical model of VFD and high-pressure pump motor, the reason for the experimental results caused by the operation change is explained theoretically. The experimental results verify that for a certain recovery rate, the specific energy consumption required for water production decreases with decreasing power frequency. This provides desalination energy savings but at the expense of permeate production speed.

Perancangan dan Pemanfaatan Penampung Air Hujan dengan Filtrasi Sederhana Skala Unit Perumahan Villa Citra Bantarjati

Bogor city is included in the region with high rainfall with an average annual rainfall of 3.500 – 4.000 mm so that the potential for rainwater harvest. This research was conducted to plan the volume of rainwater reservoirs that can be applied at the scale of Villa Citra Bantarjati housing units and design simple filtration tools to improve the physical quality of rainwater that can be used to support domestic needs. This study was conducted using primary data covering the area of roofs used in rainwater harvesting as well as secondary data in the form of maximum rainfall data in the last 15 years. Water quality testing is conducted by physical quality test of rainwater before and after passing the design of a simple filter tool to produce water quality that meets class II water quality standards. The area of the roof used to catch rainwater is 25 m2, so the average volume of availability accommodated in rainwater reservoirs is 155,31 lt/day with a water loss factor due to runoff of 20%. The capacity of rainwater reservoirs that meet domestic water needs is 330 lt. The design of this simple filter is able to improve the physical quality of rainwater with a predetermined arrangement of filter media.