• Journal of Korean Society of Environmental Engineers
• /
• v.39 no.3
• /
• pp.155-163
• /
• 2017

Membrane filtration has become more popular in drinking water treatment recently, since the filtration can control not only particulate matters but also pathogenic microorganisms such as giardia and cryptosporidium very effectively. Pilot-scale ($120m^3/d$ of treatment capacity) and test-bed ($25,000m^3/d$ of treatment capacity) microfiltration experiments were conducted to find optimum operating mode and the critical flux. Optimum operating mode of pilot-test was assessed as inflow 1.0 min, filtration 36.5 min, air backwash 0.9 min, backwash 1.0 min and outflow 1.0 min with 50 LMH ($L/min{\cdot}m3^$) of critical flux. Critical Flux was calculated to be $50L/m^2-h$ (within TMP 0.5 bar) based on the increase formula of the transmembrane pressure difference according to the change of time at Flux 20, 40, 56 and 62 LMH in pilot operation. Chemical cleaning was first acid washed twice, and alkali washing was performed secondarily, and a recovery rate of 95% was obtained in the test-bed plant. The results of operating under these appropriate conditions are as follows. Turbidity of treated water were 0.028, 0.024, 0.026 and 0.028 NTU in spring, summer, autumn and winter time, respectively. Microfiltration has superior treatment capability and performance characteristics in removing suspended solids and colloidal materials, which are the main cause of turbidity and important carrier of metal elements, and it has shown great potential in being an economically substitute to traditional processes (sand filtration).

• Membrane Journal
• /
• v.24 no.3
• /
• pp.201-212
• /
• 2014

This study was performed to discover the optimum operation conditions for the advanced water treatment using the ceramic membrane, introduced the first in the nation at the Y water treatment plant (WTP). The result of investigation to find the optimum operation conditions which can continue preserving the filtration performance as well as satisfying both the economics and the water quality is as follows. In the ordinary water quality condition of the Y WTP, the optimum filtration time(the backwash period), which can minimize the production of backwash waste and preserve the membrane performance was examined to be 4.0 hours on basis of institution capacity ($16,000m^3/day$). Examining the recovery rate of TMP from the chemical cleaning (CIP) discovered that the inorganic contaminants, which cause membrane fouling, such as iron, manganese, aluminum, were removed through the acidic cleaning using citric acid, whereas the membrane recovery rate was found to be low. But, on the other hand, the TMP was recovered to the initial value from the alkali cleaning using the NaOCl. Therefore, the main contaminant causing the fouling was determined to be hydrophilic organic compound( biopolymer). The membrane recovery rate is highly influenced by the temperature of the cleaning chemical. That is, the rate increased with increasing temperature.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.40 no.2
• /
• pp.73-78
• /
• 2007

The suitability of a flexible fiber filter for removing suspended solid (SS) in a recirculating aquaculture system was evaluated. This study focused on variation in the performance with a change in filtering time, influent water quality, and filtering mode duration. The particle distribution diagram of the filter effluent showed that the number of particles bigger than $5-8{\mu}m$ decreased dramatically, and the removal efficiency exceeded 80%. Although the removal efficiencies of SS and chemical oxygen demand (COD) were dependent on the quality of the influent, the SS and COD concentrations of the effluent were not affected by the influent concentrations. This was despite the deterioration if water quality after feeding in the rearing tank. The performance of the filter was not affected by the filtering mode duration, feeding conditions, or filtering time. The SS concentration and turbidity of the recirculating-type rearing tank were 30% and 50% lower, respectively, than of the a non-recirculating-type rearing tank under the same operating conditions. The flexible fiber filter was applicable to a recirculating aquaculture system that uses plenty of seawater, based on its low filtering resistance $(2kg_f/cm^2)$, high flux $(330m^3/m^2/hr)$, and high fine particle removal efficiency (80%, $5-8{\mu}m$).

• Membrane and Water Treatment
• /
• v.9 no.3
• /
• pp.181-188
• /
• 2018

A sidestream contains the filtrate or concentrate from the belt filter press, filter backwash and supernatant from sludge digesters. The sidestream flow, which heads back into the sewage treatment train, is about 1-3% less than the influent flow. However, the sidestream can increase the nutrient load since it contains high concentrations of phosphorus and nitrogen. In this study, the removal of PO4-P with organic matter characteristics and bacteriological changes during the sidestream treatment via ladle furnace (LF) slag was investigated. The sidestream used in this study consisted of 11-14% PO4-P and 3.2-3.6% soluble chemical oxygen demand in influent loading rates. LF slag, which had a relatively high $Ca^{2+}$ release compared to other slags, was used to remove $PO_4-P$ from the sidestream. The phosphate removal rates increased as the slag particle size decreased 19.1% (2.0-4.0 mm, 25.2% (1.0-2.0 mm) and 79.9% (0.5-1.0 mm). The removal rates of dissolved organic carbon, soluble chemical oxygen demand, color and aromatic organic matter ($UV_{254}$) were 17.6, 41.7, 90.2 and 77.3%, respectively. Fluorescence excitation-emission matrices and liquid chromatography-organic carbon detection demonstrated that the sidestream treatment via LF slag was effective in the removal of biopolymers. However, the removal of dissolved organic matter was not significant during the treatment. The intact bacterial biomass decreased from $1.64{\times}10^8cells/mL$ to $1.05{\times}10^8cells/mL$. The use of LF slag was effective for the removal of phosphate and the removal efficiency of phosphate was greater than 80% for up to 100 bed volumes.

• Journal of Korean Society on Water Environment
• /
• v.27 no.1
• /
• pp.104-109
• /
• 2011

The removal efficiencies of 2-methylisoborneol (MIB) and geosmin were investigated to reveal removal characteristics of typical organic compounds causing disagreeable taste and odor at the conventional water treatment plant installed with pulsator clarifier patented by the French company $Degr{\acute{e}}mont$. The injection rate of Powdered Activated Carbon (PAC) into water was changed step wisely as we conducted jar tests in the laboratory and water treatment in the actual plant. 2-MIB concentration decreased linearly while geosmin did exponentially along with the injection rate of PAC at our jar tests. The removal efficiency of geosmin by PAC injection was considerably higher than that of 2-MIB. In the real pulsator clarifier, 2-MIB concentration started decreasing as the injection rate reached up to 10 mg/L of PAC. On the other hand, the concentration of geosmin in water decreased proportional to the injection rate of PAC. In the sand filtration, removal efficiencies of 2-MIB and geosmin on July were much higher than those on March. It was carefully suggested beforehand and found afterwards that general microorganisms notably existed in the sand filter with no chlorine in filter influent and backwash water and the sand filter biologically activated removed much more odor compounds. It was considered as the reason why the removal efficiency of 2-MIB and geosmin was increased. The microbial activity maybe increased in summer with water temperature rising and low filtration rate possibly increased contact time between odor compounds and general microorganisms.

• Journal of Korean Society of Water and Wastewater
• /
• v.37 no.5
• /
• pp.271-279
• /
• 2023

Fouling is an inevitable problem in membrane water treatment plant. It can be measured by trans-membrane pressure (TMP) in the constant flux operation, and chemical cleaning is carried out when TMP reaches a critical value. An early fouilng alarm is defined as warning the critical TMP value appearance in advance. The alarming method was developed using one of machine learning algorithms, decision tree, and applied to a ceramic microfiltration (MF) pilot plant. First, the decision tree model that classifies the normal/abnormal state of the filtration cycle of the ceramic MF pilot plant was developed and it was then used to make the early fouling alarm method. The accuracy of the classification model was up to 96.2% and the time for the early warning was when abnormal cycles occurred three times in a row. The early fouling alram can expect reaching a limit TMP in advance (e.g., 15-174 hours). By adopting TMP increasing rate and backwash efficiency as machine learning variables, the model accuracy and the reliability of the early fouling alarm method were increased, respectively.

• Journal of Korean Society of Environmental Engineers
• /
• v.35 no.12
• /
• pp.877-882
• /
• 2013

The application of ultrafiltration (UF) and microfiltration (MF) membranes has been increased for drinking water purification. The advantages of UF/MF membrane process compared to conventional treatment processes are stable operation under varying feed water quality, smaller construction area, and automatic operation. Most membrane treatment plants are designed with polymeric membranes. Recently, some studies suggested that the process of treating surface water with ceramic membranes is competitive to the application of polymeric membranes. Higher water flux, less frequent cleaning, and much longer lifetime are the advantages of ceramic membrane comparing to polymeric membrane. Therefore, this research focused on the application of ceramic MF membrane pilot plant at the slow sand filtration plant. The ceramic membrane pilot plant has three trains that used raw water and sand filtered water as a feed water, respectively. For optimizing the pilot plant process, the coagulation with PACl coagulant was used as a pretreatment of ceramic membrane process. In addition, CEB (Chemical Enhanced Backwash) process using $H_2SO_4$ and NaOCl was used for 1.5 days, respectively. The experimental results showed that applying the optimum coagulant dose before membrane filtration showed enhancing membrane fluxes for both raw water and sand filtered water. Also, when using raw water as a feed of membrane, minimum fouling rate was 2.173 kPa/cycle with 25 mg/L of PACl and when using sand filtered water, the minimum fouling rate was 0.301 kPa/cycle with 5 mg/L of PACl.