• Environmental Engineering Research
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• v.21 no.1
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• pp.45-51
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• 2016

Membrane bioreactor (MBR) and reverse osmosis (RO) membrane system was applied to the treatment and reclamation of textile wastewater in Thailand. An experiment was carried out to determine the fouling behavior and effect of anti-scalant and biocide addition to flux decline and its recovery through chemical cleaning. The RO unit was operated for one month after which the fouled membranes were cleaned by sequential chemical cleaning method. RO flux was found rapidly declined during initial period and only slightly decreased further in long-term operation. The main foulants were organic compounds and thus sequential cleaning using alkaline solution followed by acid solution was found to be the most effective method. The provision of anti-scalant and biocide in feed-water could not prevent deposition of foulant on the membrane surface but helped improving the membrane cleaning efficiencies.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.3
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• pp.138-146
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• 1989

This experiment was conducted to utilize the water soluble protein from the fish meal in wastewater as nitrogen source by alkaline protease producting bacteria and to investigate the culture condition of the production. G-12 and G-14 strains having the strong activity of the alkaline pretense were isolated from sea water. These strains were identified as Pseudomonas chlororaphis and Pseudomonas alcaligenes according to physiologycal characteristics, respectively. In enzyme production, galactose and casein for G-12 strain, and raffinose and the water soluble protein of the fish meal wastewater for G-14 strain was favorable as carbon and nitrogen source. An action of inhibition appeared in all of the metal salts used. The optimal temperature of enzyme production was $30^{\circ}C$ for all strains. Optimal initial pH for the enzyme formation in G-12 and G-14 strains was pH 10.0 and 8.0. When these two strains were incubated for $30\~35$ hours in the optimal production medium, the enzyme production reached at maximum.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.2
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• pp.183-192
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• 2015

Response surface methodology (RSM) based on a Box-Behnken Design (BBD) was applied to optimize the thermal-alkaline pre-treatment operating conditions for anaerobic digestion of flotation scum in food waste leachate. Three independent variables such as thermal temperature, NaOH concentration and reaction time were evaluated. The maximum methane production of 369.2 mL $CH_4/g$ VS was estimated under the optimum conditions at $62.0^{\circ}C$, 10.1% NaOH and 35.4 min reaction time. A confirmation test of the predicted optimum conditions verified the validity of the BBD with RSM. The analysis of variance indicated that methane production was more sensitive to both NaOH concentration and thermal temperature than reaction time. Thermal-alkaline pretreatment enhanced the improvement of 40% in methane production compared to the control experiment due to the effective hydrolysis and/or solubilization of organic matters. The fractions with molecular weight cut-off of scum in food waste leachate were conducted before and after pre-treatment to estimate the behaviors of organic matters. The experiment results found that thermal-alkaline pre-treatment could reduce the organic matters more than 10kD with increase the organic matters less than 1kD.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.6
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• pp.481-490
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• 2017

Water and wastewater treatment has always been a challenging task due to the continuous increase in amount and the change in characteristics of the poorly biodegradable and highly colored organic matters, as well as harmful micro-organisms. Advanced techniques are therefore required to successfully remove these pollutants from water before reuse or discharge to receiving water bodies. Application of ozone, which is a powerful oxidant and disinfectant, alone or as part of advanced oxidation process depends on the complex kinetic reactions and the mass transfer of ozone involved. Micro- and nano bubbling considerably improves gas dissolution compared to conventional bubbles and hence mass transfer. It can also intensify generation of hydroxyl radical due to collapse of the bubbles, which in turn facilitates oxidation reaction under both alkaline as well as acidic conditions. This review gives the overview of application of micro- and nano bubble ozonation for purification of water and wastewater. The drawbacks of previously considered techniques and the application of the hydrodynamic ozonation to synthetic aqueous solutions and various industrial wastewaters are systematically reviewed.

• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.301-306
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• 2009

This research was carried out to establish the effective treatment condition and characteristic of wastewater from the electroplating plant of cold rolling mill by using microorganism. Alkaline wastewater and acidic heavy metal wastewater accounted for 64%, 30%, respectively, of the total wastewater. Highly concentrated thiocyanate was 53890 mg/L as COD and it was 53% of total COD, even though it was 0.03% of wastewater from the electroplating plant. When treating mixed wastewater with microorganism, it was easy to remove when SCN concentrations of mixed wastewater was 200 mg/L or less. While the treatment effect of COD-causing materials was low at the concentration of 400 mg/L or less, it implies that highly concentrated thiocyanate contains a large amount of slowly biodegradable organics. When treating with mixed wastewater, pH was 7.33 at the beginning, but after 8 hours it increased to 7.99. This is caused by ammonia which is generated when SCN of highly concentrated thiocyanate was degraded by microorganism.

• Journal of the Korean Professional Engineers Association
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• v.14 no.1
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• pp.22-29
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• 1981

This study concernes the decomposition of cyanide ion in electroplating plant wastewater and COD variation of photodeveloping wastewater under various conditions. Determinations of CN- concentration were carried out by AgNO$_3$ titration method. The sample solutions were pretreated by passing ozone and decompositions were checked as a function of time for ozone treatment. Analysis of film developing wastewater was carried out by KMnO$_4$ method. Electroplating plant wastewater was also examined at various pH; decomposition rate of cyanide ion was found to increase at higher pH. Time required for the decomposition could be shortened by removing the heavy metal ions under alkaline condition. The effect of temperature on decomposition was studied at 40$^{\circ}$ and 60$^{\circ}C$. The result was better at 40$^{\circ}C$ although time for decomposition was almost same at both temperatures. Analysis of film developing wastewater revealed that COD decrease was faster during the first 1 to 2 hours. However, further decrease could not be effected. The existence of unknown special organics resistant to the decomposition was believed to be the reason.

• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.40-45
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• 1999

This study deals with an investigation on low cost adsorbents locally available n dyeing wastewater treatment of color removal. Peat, bentonite, slag and fly ash were utilized for this study. Considering that low cost adsorbents contained in $SiO_2$, $Fe_2O_3$ and $Al_2O_3$ compositions, and coagulants were mainly used aluminate and ferrate in color removal. Color of dyeing wastewater was high removed in peat, berntonite and slag except for fly ash with passed time. It could be known that color removal of peat and slag were increased to pH 4, but was hardly changed with advancing to alkaline. Color intended to be high removed with increasing of agitation speed but to be almost slow after 150rpm. As a result on the experiment of Freundlich adsorption isotherms, adsorption intensity(l/n) appeared to be peat>fly ash>slag>bentonite and adsorption capacity(k) came out peat>bentonite>slag>fly ash. Therefore, if low cost adsorbents substituted for existing adsorbents, peat, bentonite and slag could look forward to an expected economical effect.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.240-244
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• 1998

This study was carried out to investigate the efficiency of steel mill slag and sludge in removing heavy metals and cyanide in metal plating wastewater. Laboratory experiments were peformed with jar tester, The tests were peformed at ambient temperature. The results of tests showed that overall rates metals removed were greater than 90 %. Metals were removed from solution as the combined effects of adsorption and precipitation in alkaline condition. The removal efficiency of cyanide by steel mill wastes was above 90 % at optimum conditions. In view of the test results and other engineering characteristics of steel mill slag and sludge, these industrial by-products from steel industry have a high potential to be used in metal plating wastewater treament and were particularly beneficial.

• Journal of Environmental Health Sciences
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• v.22 no.3
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• pp.81-87
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• 1996

The purpose of this research is to examine the utilization of oyster shells for neutralization and removal of heavy metal ions in plating wastewater, because oyster shells have been known to be very porous, to have high specific surface area and to have alkaline minerals such as calcium and magnesium. The results obtianed from this research showed that oyster shells had a buffer capacity to neutralize an acidic.alkali system in plating wastewater. Generally, it could be showed that the removal efficiencies of heavy metal ions were very influenced by reaction times and oyster shell dosages. In point of ocean waste, if oyster shells substituted for a valuable adsorbent such as actviated carbon, they could look forward to an expected economical effect.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.4
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• pp.409-415
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• 2016

Magnetite particles were synthesized by co-precipitation of water-soluble 밀 스케일-derived precursor by various concentrations of (0.5, 0.67, 1, 2 N) NaOH and (0.6, 0.8, 1.2, 2.4 N) $NH_4OH$. It is theoretically known that as the concentration of the alkaline additive used in iron oxide synthesis increases, the particle size distribution of that iron oxide decreases. This trend was observed in both kind of alkaline additive used, NaOH and $NH_4OH$. In addition, the magnetite synthesized in NaOH showed a relatively smaller particle size distribution than magnetite synthesized in $NH_4OH$. Crystalline phase of the synthesized magnetite were determined by X-ray diffraction spectroscopy(XRD). The particles were then used as an adsorbent for phosphate(P) removal. Phosphorus adsorption was found to be more efficient in NaOH-based synthesized magnetite than the $NH_4OH$-based magnetite.