This study is focused on manganese (Mn(II)) removal by ozonation in surface water. Instant ozone demand for the water was 0.5 mg/L in the study. When 0.5 mg/L of Mn(II) is existed in water, the optimum ozone concentration was 1.25 mg/L with reaction time 10 minutes to meet the drinking water regulation. The ozone concentration to meet the drinking water regulation was much higher than the stoichiometric concentration. The reaction of soluble manganese removal was so fast that the reaction time does not affect the removal dramatically. When Mn(II) is existed with Fe, the removal of Mn(II) was not affected by Fe ion. However As(V) is existed as co-ion the removal of Mn(II) was decreased by 10%. Adding ozone to surface water has limited effect to remove dissolved organic matter. When ozone is used as oxidant to remove Mn(II) in the water, the existing co-ion should be evaluated to determine optimum concentration.

In this experimental study, it is concerned to develop a simple equation using jar-test results in order to predict the optimum dosage of coagulant, PAC(polyaluminum chloride). Considering the relationships with the reactions of coagulation and flocculation, the four independent variables (e.g. turbidity, temperature, pH and alkalinity) are selected out of many parameters and they are put into calculations to develop an equation by means of multi-regression method. As the result, the dosing rate of PAC is proportional to turbidity, pH and alkalinity, but in inverse to temperature. And the developed equation is as follow, D c = 3.2 ⋅ T 0.37 ⋅ A 0.04 ⋅ P 0.5 t 0.1 , ( R 2 = 0.9443 ) And also, comparing between the estimated value from the equation and the real dosing rate in the plant, Kwangam and Tdukdo, during 1988~1991, it is represented an agreement having a relative error of 16.4%, 17.8%, respectively.

The consecutive combination process of a biological process as the pre-treatment and a chemical process as the post-treatment is applied for the dyeing wastewater. The poor efficiency of biological treatment using pure oxygen makes the chemical treatment cost high. It is necessary to improve the efficiency of biological treatment in order to reduce the cost of chemical treatment. The purpose of this paper is to find the minimum dose of chemical reagent to fit the Discharged Water Quality Standards for the different biological treatment effluents. Results revealed that the minimum dosage of Fenton's reagent lead to save the cost of chemical treatment based on the guideline dose in the treatment plant. The possible maximum saving reagents was up to 70% for the effluent of the pilot plant packed with the carrier imbedded microorganisms which were selected from the present treatment plant.

The optimum dosage of quicklime in producing organic fertilizer using livestock wastes with a greater than 80% water content was analysed. After one day had elapsed to allow for the organic fertilizer to dry, the quicklime dosage and the composition of the organic fertilizer were analysed. Any from done to the organic fertilizer was also assessed. The amount of the quicklime required to stabilize livestock wastes was determined by water content of livestock wastes. For J farm(slurry style) of which livestock wastes have 94.6% of water concentration, less than 3% of total amount of livestock wastes, for H farm(scraper style) of which livestock wastes have 85% of water concentration, less then 4% of total livestock wastes and Y farm(traditional style) of which livestock wastes have 80% of water concentration, less then 5% of total livestock wastes. Generally, in order to pack the organic fertilizer, water containing quicklime-stabilized livestock wastes should be less than 35%. It takes 9 days to keep this water content for the wastes from H and Y farms(less than 85% in water content), and 12days for the wastes from J farm(94.6% in water content). According to the classification standard for compost constitution by Higgins, the crude fertilizers from all 3 farms had high grade K2O and CaO, the middle grade T-N and middle or low grade P2O5. Stabilization by quicklime is known to inhibit bacterial decomposition of organic matter and the activity of pathogenic organisms. In this study, more than 99.99% of coliform group, fecal group and viable cell count were reduced. Our results indicate that livestock wastes of greater 80% water content could be used to produce organic fertilizer without the addition of a material for moisture control.

This study was performed to determine the optimum coagulant dosing for effective treatment of raw water in Chinyang lake. Removal rates of algae and characteristics of the water according to coagulants dosage were investigated by treatment with Microcystis aeruginosa, which is a kind of blue-green algae, to the raw water below 5NTU. The coagulants dosage for maximum removal rate of algae were 30 ㎎/ℓ of Alum, 30 ㎎/ℓ of PAC and 10 ㎎/ℓ of PACS, respectively. The removal rate of algae in 30 ㎎/ℓ of PAC was highest as 85% compared with the other treatments. At the point of maximum removal rate of algae, the removal rates of turbidity were 34%, 66% and 22% in Alum, PAC and PACS, respectively. Residual Al was decreased depend upon decreasing turbidity in water by treatment of Alum or PAC, but decreased depend upon increasing turbidity in water by treatment of PACS. The removal rate of Mn2+ in water was high in the order of Alum, PAC and PACS treatment. And Fe2+ in water was not changed by treatment of these coagulants. Particle numbers distributions according to the particle size of suspended solids that were not precipitated at 8 min. of settling time after treatment of coagulants dosage for the maximum removal rate of algae were investigated. Most of the particle sizes were below 30 ㎛ and particle numbers distributions below 10 ㎛ were 64%, 56% and 66% by treatment of Alum, PAC and PACS, respectively. Zeta potential was in the range of -6.1∼-9.7 mV at optimum coagulants dosage for algae removal.