• Environmental Engineering Research
• /
• v.23 no.4
• /
• pp.474-484
• /
• 2018

The cleaning efficiency of reverse osmosis (RO) membranes inevitably fouled by organic foulants depends upon both chemical (type of cleaning agent, concentration of cleaning solution) and physical (cleaning time, flowrate, temperature) parameters. In attempting to determine the optimal procedures for chemical cleaning organic-fouled RO membranes, the design of experiments concept was employed to evaluate key factors and to predict the flux recovery rate (FRR) after chemical cleaning. From experimental results and based on the predicted FRR of cleaning obtained using the Central Composite Design of Minitab 17, a modified regression model equation was established to explain the chemical cleaning efficiency; the resultant regression coefficient ($R^2$) and adjusted $R^2$ were 83.95% and 76.82%, respectively. Then, using the optimized conditions of chemical cleaning derived from the response optimizer tool (cleaning with 0.68 wt% disodium ethylenediaminetetraacetic acid for 20 min at $20^{\circ}C$ with a flowrate of 409 mL/min), a flux recovery of 86.6% was expected. Overall, the results obtained by these experiments confirmed that the equation was adequate for predicting the chemical cleaning efficiency with regards to organic membrane fouling.

• Membrane Journal
• /
• v.29 no.2
• /
• pp.96-104
• /
• 2019

The purpose of this paper is whether or not the in-situ restoration of the reverse osmosis (RO) membranes which its membrane function is lost is possible. The damaged RO membranes are double coated through the salting-out method by the poly(styrene sulfonic acid) sodium salt as the cationic exchange polymer and the polyethyleneimine as the anionic exchange polymer and also conducted the opposite order of the coating materials. And according to the concentration, time and ionic strength, the flux and rejection are measured for the coated membranes. Then the best coating condition is to apply for the RO membrane module of the household water purifier to know the possibility of the in-situ restoration for the commercial module. When the condition of the PEI 30,000 ppm (IS = 0.1)/PSSA 20,000 ppm (IS = 0.7) is applied, the rejection was enhance from 69% for the damaged module to 86% (90% for the pristine module).

• Korean Journal of Food Science and Technology
• /
• v.51 no.1
• /
• pp.7-11
• /
• 2019

Reverse osmosis (RO) was applied to onion juice to produce concentrated onion juice with improved flavor. The volatile compound profiles of concentrated onion juice and onion juice were compared using solvent-assisted flavor evaporation followed by gas chromatography-mass spectrometry. Onion juice and RO-concentrated onion juice contained 48 and 62 distinct volatile compounds, respectively, and included alcohols, aldehydes, esters, terpenes, furans, ketones, acids, hydrocarbons, and sulfur-containing compounds. The RO-concentrated onion juice contained a greater number of volatile flavor compounds than did onion juice. Notably, sulfur-containing compounds, which are characteristic volatile flavor compounds in raw onions, were more abundant in the RO-concentrated onion juice than in onion juice. The volatile compound composition indicates that RO-concentration produces good quality onion juice.

• Journal of Appropriate Technology
• /
• v.6 no.2
• /
• pp.183-189
• /
• 2020

Developing countries are areas where many problems arise from poor drinking water infrastructure. Developing countries often use groundwater as their primary source of drinking water, which causes problems. Among them, coastal areas are easily exposed to saltwater intrusion due to their geographical characteristics. Groundwater in areas exposed to saltwater intrusion has higher salinity than usual. If you continue to consume high salinity groundwater can cause a variety of fatal effects on the human body. Therefore, various alternatives have been proposed. This study explores the applicability of CDI(Capacitive Deionization) and RO(Reverse Osmosis) for water purification systems in areas where saltwater intrusion has occurred. Therefore, we will evaluate this by conducting water purification experiment. On the other hand, the supply of electricity is also important in the operation of water purification facilities. However, in many areas of developing countries, electricity is often not available. Therefore, this study intends to calculate the power consumption required for the actual use of the filter and to include it in the evaluation.

• Korean Journal of Food Science and Technology
• /
• v.23 no.4
• /
• pp.471-477
• /
• 1991

The optimum conditions for the development of a lactic acid beverage from the concentrated whey were studied using reverse osmosis system. For lactose hydrolysis rate and acid productivity, the strain mixture of Streptococcus thermophilus and Lactobacillus bulgaricus was more efficient than that of Streptococcus cremoris and Streptococcus lactis. The titratable acidity was increased at higher LCR (lactose concentration ratio) of whey. However, the higher LCR of whey was, the slower the pH decreasing rate was. The amount of sediment was maximum at LCR of 1.0 : 1 whey, hit there was no sediment at LCR 3.0 : 1 whey after 12 hours. Propylene glycol alginate was the best stabilizer and prevented from sedimentation at the concentation of less than 0.1%. Aspartame as a sweetener of yoghurt flavor had the best palatability.

• Clean Technology
• /
• v.9 no.2
• /
• pp.49-55
• /
• 2003

The generation of livestock wastewater in Korea amounts to $130,000m^3/day$, 0.43% of the total waste water volume, but which corresponds to 8.6% of total BOD loading. Furthermore this wastewater contains a large amount of nitrogen and phosphorus that are major causes of eutrophication in rivers and lakes. The average volume of livestock wastewater in a Korea's single farm is only $2.5m^3/day$, which necessitates development of a simple and economical process for the removal of nitrogen and phosphorus. Introduction of filtration method removes more than 90% of suspended solids. Subsequent application of reverse osmosis removes more then 95% of total nitrogen and phosphorus in the wastewater. The effluent of this treatment will yield less than 200 mg/L of total nitrogen and 1 mg/L of total phosphorous, which are lower than 260 mg/L of total N and 50 mg/L of total P, the regulation values of Ministry of Environment, Korea. Treating $2m^3/day$ of livestock wastewater was found to be feasible with the application of filtration and reverse osmosis and the electricity requirement was estimated to be about 30 Kwh/month.

• Membrane Journal
• /
• v.25 no.4
• /
• pp.332-342
• /
• 2015

In this study, to solve the major problem of reverse osmosis (RO) membrane, surface of reverse osmosis membrane was modified by silane-epoxy multi layer. Octyltrimethoxysilane (OcTES) was polymerized to membrane surface via cross-linking by Sol-gel method. n = 8 alkylgroup of OcTES formed the branch structure by self assembly. And for improve fouling resistance of RO membrane, Ether group of ethylene glycol diglycidyl ether (EGDE) was given to improve hydrophilicity of RO membrane surface by ring-opening. To analyze structure of RO membrane surface with FE-TEM and AFM. Membrane surface of the ridge and valley structure and the bridge structure was confirmed due to the multi-layer surface modification of OcTES and EGDE. And through the increase of the roughness, the branch structure was formed well on membrane surface. Through the XPS analysis was identified chemical structure of membrane surface. And confirmed that the hydrophilic surface modification is given to the surface of the film through a Contact angle analysis. In optimization of EGDE surface modification condition, was suitable 0.5 wt% EGDE concentraion and $70^{\circ}C$ ring-opening temperature. In result of fouling resistance test and MFI is SUL-H10, $PA-OcTES_{1.0}$, $PA-OcTES_{1.0}-EGDE_{0.5}$ 68.7, 60.4, 5.4 ($10E-8hr/mL^2$), multi-layer surface modified membrane improved fouling resistance.

• Membrane Journal
• /
• v.19 no.3
• /
• pp.183-188
• /
• 2009

After membrane fouling factors in acrylic wastewater were minimized by pretreatment process accompanied with $TiO_2$, it was utilized in MF/UF/RO process. After composing of ultrafiltration/reverse osmosis or microfiltration/reverseosmosiss module set according to types and kinds of membrane, the separation characteristics were examined with the variation temperature and pressure using pretreated acrylic wastewater by membrane module sets. The permeate of ultrafiltration or microfiltration module was sent to reverse osmosis module. It was found that final permeate flux of reverse osmosis module in module set 2 (MWCO 200,000 UF+RO) was excellent. It was shown that the removal efficiency of TDS, T-N and COD was very low and was not dependent on the variation of temperature and pressure in UF and MF modules. From the above result, the removal efficiency of TDS, T-N and COD was very excellent in RO module. The removal efficiency of turbidity in UF and MF module was very high (> 99% removal efficiency). Final water quality of acrylic wastewater treated by the membrane module set was satisfied with effluent allowances limit and membrane module sets were ascertained to reuse wastewater.

• Membrane Journal
• /
• v.30 no.3
• /
• pp.190-199
• /
• 2020

The utilization of multiple water sources becomes important due to the master plan for development of water supply released by Ministry of Environment, Korea in 2018. In this study, therefore, the analysis of comprehensive effect in blending applicable water sources in Daesan where 100,000 ㎥/d seawater desalination plant will be constructed for industrial use was performed. The increase in mixing ratio of other water sources with seawater reduced salinity up to 50%, but negatively impacted the turbid and organic matter. Lab-scale reverse osmosis performance test also found that membrane fouling was exacerbated in blended water condition. The simulation results of reverse osmosis indicated 39% energy saving on average is expected at the one-to-one blending ratio, however, long-term performance test at the pilot-scale plant is highly required to evaluate the inclusive impact of mixing seawater and other water sources.

• Applied Chemistry for Engineering
• /
• v.17 no.5
• /
• pp.521-526
• /
• 2006

A membrane bioreactor (MBR) is an effective tool for wastewater treatment with recycling. MBR process has several advantages over conventional activated sludge process (ASP); reliability, compactness, and quality of treated water. The resulting high-quality and disinfected effluents suggest that MBR process can be suitable for the reused and recycling of wastewater. An anoxic/oxic (A/O) type MBR was applied to simultaneous removal of organics and nutrients in sewage. At first, the efficiency of submerged MBR process was investigated using a hollow fiber microfiltration membrane with a constant flux of $10.2L/m^2{\cdot}h$ at each solids retention time (SRT). Results showed that protein/carbohydrate (P/C) ratio increased and total extracellular polymeric substances (EPS) remained constant with SRT increased. Secondly, A/O type MBR with a reverse osmosis (RO) membrane was employed to treat the municipal wastewater. The performance of A/O type MBR-RO process is better for the treatment of organics and nutrients than ASP-MF-RO process in terms of consistent effluents quality.