In this study, solid-liquid separation conditions for coagulation and sedimentation experiments using inorganic coagulant (aluminum sulfate and Poly-Aluminum Chloride (PAC)) were optimized with brine wastewater discharged by the epoxy-resin process. When the turbidity and suspended solid (SS) concentration in raw wastewater were 74 NTU and 4.1 mg/L, respectively, their values decreased the lowest in a coagulant dosage of 135.0 - 270.0 mg Al3+/L. The epoxy resin was re-dispersed in the upper part of wastewater treated above 405.0 mg Al3+/L. The removal efficiencies of turbidity and SS via dosing with aluminum sulfate and PAC were evaluated at initial turbidity and SS of 74 - 630 NTU and 4.1 - 38.5 mg/L, respectively. They increased most in the range from 135.0 - 270.0 mg Al3+/L. The solid-liquid separation condition was quantitatively compared to the correlation of SS removal efficiency between the coagulant dosage and SS concentration based on the concentration of aluminum ions. The empirical formula,   , shows the relationship between SS removal efficiency (R) and coagulant dosage (D) at 38.5 mg/L; it produced high correlation coefficients (r2) of 0.9871 for aluminum sulfate and 0.9751 for PAC.

In this study, zeolite (Z-C2) was synthesized using a fusion/hydrothermal method on coal fly ash (FA) discharged from a thermal power plant in the Ulsan area and then analyzed via scanning electron microscopy (SEM) and X-ray diffraction (XRD). The Z-C2 was characterized in terms of mineralogical composition and morphological analysis. The XRD results showed that its peaks had the characteristics of Na-A zeolite in the range of 2θ of 7.18~34.18. The SEM images confirmed that the Na-A zeolite crystals had a chamfered-edge crystal structure almost identical to that of the commercial zeolite. The adsorption kinetics of Cu, Co, Mn and Zn ions by Z-C2 were described better by the pseudo-second-order kinetic model more than by the pseudo-first-order kinetic model. The Langmuir model fitted the adsorption isotherm data better than the Freundlich model did. The maximum adsorption capacities of Cu, Co, Mn and Zn ions obtained from the Langmuir model were in the following order : Cu (94.7 mg/g) > Co (77.7 mg/g) > Mn (57.6 mg/g) > Zn (51.1 mg/g). These adsorption capacities are regarded as excellent compared to those of commercial zeolite.

The goal of this study was to evaluate micro-bubble concentration (Cair) in water by air/water ratio (A/W ratio) with a micro-bubble generating pump. The estimation of micro-bubble concentration is based on the balance of inlet/outlet air and water flow rate. On net A/W ratio to be generated micro-bubble, we found that the obtained the Cair are shown as a function of discharge pressure (Pg) of the micro-bubble generating pump. The correlation of the Cair and the Pg(Cair =3.261Pg-1.754) was adequately described by the least square methods with a high correlation coefficient (r = 0.9459) and calculated values fit the experimental data quite well. The Cair was lower than theoretical dissolved air concentration (Caq) calculated by Henry’s law. The Cair for being operated the micro-bubble generating pump was 6.75 – 39.53 mL/L, however, we found that the optimum of the Cair to generate micro-bubble was the range from 10 to 12 mL/L.

The sludge flotation/thickening apparatus equipped a micro-bubble generating pump was used to investigate micro-bubble generating properties on operational parameters. We evaluated micro-bubble generating properties as results to be operated the apparatus by operational parameters which are pump discharge pressure, air/water ratio(A/W ratio), air flow rate, and water flow rate. Micro-bubble generating efficiencies in pumps without recycling flow and with 50% of recycling flow was found to be very efficient on optimum A/W ratio from 1.06 to 3.62% and optimum A/W ratio from 1.05 to 4.06%, respectively. In condition of 3.6% of A/W ratio, we showed that the apparatus could be generated 36,000 ppm of micro-bubble concentration to be optimum treatment efficiency in sludge thickening process.

This study found that flotation efficiencies for removing algae and micro particles in raw water were optimized on mixing intensity and time of the mixing and flocculation conditions with a continuous DAF system. It is more efficient for mixing intensity at 23.1 s-1 and time at 660 s(Gt value : 15246) to float flocculated floc with the raw water in M water treatment plant. Flotation efficiency was more than about 0.9 when operated pressure and A/S ratio were sustained at 5 kgf․cm-2 and up to 0.056 mL․mg-1. The continuous DAF system made by the study could be continuously operated for 20 days and sustained not exceeding 4 NTU with raw water with low turbidity(13.4 ～ 9.8 NTU).

The biosorption of dye, Rhodamine B(Rh-B), onto waste activated sludge was investigated. The biosorption capacity and contact time were shown as a simulation of dye adsorption equilibrium and kinetics models. We observed that biosorption of Rh-B occurred rapidly less than 4hr. These experimental data could be better fitted by a pseudo-second-order rate equation than a pseudo-first-order rate equation. The equilibrium dependence between biosorption capacity and initial concentration of Rh-B was estimated and it was found that the equilibrium data of biosorption were fitted by four kinds of model such as Langmuir, Freundlich, Redlich- Peterson, and Koble-Corrigan model. The average percentage errors, ε(%), observed between experimental and predicted values by above each model were 21.19%, 9.97%, 10.10% and 11.76%, respectively, indicating that Freundlich and Redlich-Peterson model could be fitted more accrately than other models.

Waste sludge may be used to recovery wastewater contaminated with heavy metals. The waste sludge is an inexpensive readily available source of biomass for biosorption with metal-bearing wastewater. The biosorption of heavy metals such as Pb(II), Cu(II), Cr(II), and Cd(II) onto waste sludge was investigated in batch experiments and waste sludge loaded heavy metals was separated by dissolved air flotation. The biosorption equibria of heavy metals could be described by Langmuir and Freundich isotherms. The adsorption capacity for waste sludge was in the sequence of Pb(II)>Cr(II)>Cu(II)>Cd(II). The system attained equilibrium about 20 min. The Langmuir and Freundlich adsorption model effectively described the biosorption equilibrium of Cu(II) and Cr(II) ions on waste sludge. Maximum adsorption capacity of Cu(II) and Cr(II) were 196.08 and 158.73 mg/g, respectively. Solid-liquid separation efficiencies were kept above 95% on waste sludge loaded heavy metals, and were decreased with pH increasing.

The relationships between subjective symptoms of toluene exposed workers and concentration of their urinary excretion of hippuric acid were investigated. The exposed groups of 146 workers exposed to toluene and the control groups of 47 workers have never been exposed to toluene in Ulsan area were selected and studied. Hippuric acid was measured by HPLC, and counts of blood cells and liver function test were also performed. The mean value of urinary hippuric acid concentration of the control group was 0.322(±0.267) g/L, while that of the exposed group was 1.260(±0.395) g/L. As the concentration of hippuric acid had statistical proximity in 0.1% level, WBC, GOT, and GPT didn't have any proximity(P>0.05). The exposed group showed lower level of leucocyte counts 6522.40(1710.3) than the control group 6891.50(1483.7). The exposed group showed higher level of GOT(25.75), GPT(27.09) than GOT(23.75), GPT(25.21) of the control group. Dried skin was the highest complained symptom of toluene exposed workers, the second strained eye, the third poor auditory function, and the fourth was headache.

Sludge discharger applied the principle of the air lift pump was investigated experimentally for the different design(diameter of discharge pipe, diameter and height of the inside and outside wall) and operating parameters(air flow rate, water level). And it was conducted that performance comparison about sludge discharger and conventional air lift pump. The result indicated that discharged liquid were increased with the increase of air flow rate and water level and decrease distance between inside and outside wall. The discharge pressure was increased with an increase of air flow rate and a decrease of the diameter of the discharge pipe, for both the sludge discharger and the airlift pump. The discharge pressures of the sludge discharger were 3-6 times higher than those of the air lift pump.

The properties of biosorption of dye(Rhodmine B) was investigated to figure out the effects of temperature as a function of dye concentration and sludge concentration by the Langmuir and Lagergen adsorption model. It was found that the uptake capacity of biosorption was increased at low temperature. The Langmuir adsorption model was found suitable for describing the biosorption of the dye. The experimental results indicated that the dye uptake process followed the pseudo-first-order kinetics.

The photocatalytic oxidation of Rhodamine B (RhB) was studied using immobilized TiO2 and fluidized bed reactor. Immobilized TiO2 onto GF/C was employed as the photocatalyst and a 30 W germicidal lamp was used as the light source and the reactor volume was 4.8 L. The effects of parameters such as the amounts of photocatalyst, initial concentration, initial pH, air flow rate and anion additives (NO3-, SO42-, Cl-, CO32-) competing for reaction. The results showed that the optimum dosage of the immobilized TiO2 was 40.0 g/L. Initial removal rate of immobilized TiO2 was expressed Langmuir - Hinshelwood equation.

Anaerobic/aerobic reactor system was used to treat a synthetic wastewater with glucose as carbon sources(0.38˜2.29 kg COD/m3.day) and Acid Red 14(1.05˜24.00 g Acid Red 14/m3.day, color degree of 570˜1710). COD removal efficiency by the anaerobic stage in operation period were above 90 % organic loading rate of 0.38˜2.29 kg COD/m3.day(except, adaptation period) and the removal efficiency of the whole system were above 96 %. The decolorization of the Acid Red 14 was through the alteration of the dye structure(or cleavage of the Azo bond) during the anaerobic treatment. In the A/A system, the anaerobic stage played an essential role in removing both color and COD. In addition it also improves biodegradability of dye for further aerobic treatment. After operation, average MLSS concentration of anaerobic sludge reactor, anaerobic fixed-bed reactor and aerobic fixed-bed reactor were 17100mg/L, 20000mg/L, and 10000mg/L, respectively.

Wastewater from the pigment industry has high levels of organics and is known as hardly biodegradable. The objective of this study is to evaluate the applicability of aerobic fixed-bed biofilm reactor packed with ceramic support carrier for the pigment wastewater treatment. Orange 2(widely used azo pigment) adsorption experiment onto biofilm and activated sludge, and continuous treatment experiments were performed. In batch adsorption experiment, maximum adsorption quantity of biofilm was at least two times higher than that of activated sludge. In continuous experiment using aerobic fixed-bed biofilm reactor, the influent concentration of COD and Orange 2 were 75∼500㎎/ℓ(0.45∼3.00㎏ COD/㎥.day), 5∼50㎎/ℓ (0.03-0.30㎏ Orange 2/㎥.day), respectively. At a COD loading rate of 2.5㎏ COD/㎥.day and Orange 2 loading rate of 0.18㎏ Orange 2/㎥.day, removal efficiency of COD and Orange 2 were over 95%, 97%, respectively.

Biosorption of Pb was evaluated for plants, Persicaria chinensis, Oenanthe javanica and Salvinia natans. The adsorption equilibrium was reached in about lhr for Pb and the highest adsorption capacity was 150㎎ Pb/g biomass at S. natans. Pb adsorption process showed a pseudo second order irreversible reaction. The highest initial adsorption rate was 2000㎎ Pb/g biomass/hr at O. javanica. In spite of pH variation, Pb adsorption capacity by P. chinensis was maintained uniformly. When light metals concentrations were increased in the solution, Pb was selectively adsorbed. The selectivity of mixture solution showed the adsorption order of Pb>Cu>Cr>Cd. The Pb adsorption capacity of P. chinensis pretreated with NaOH was increased by 30% in comparison with that of no treatment.

Pb2+ and Cr3+ uptake capacity by Sargassum horneri was 185.5㎎ Pb2+/g biomass and 102.6㎎ Cr3-/g biomass, respectively. An adsorption equilibria were reached within about 0.5 hr for Pb2+ and 1 hr for Cr3+. The adsorption parameters for Pb2+ and Cr3+, were determined according to Langmuir and Freundlich model. With an increase in pH values of 2 to 5, Pb2+ uptake was increased, however Cr3+ uptake was constant. The selectivity of mixture solution showed the uptake order of Pb2+>Cu2+>Cr3+>Cd2+. Pb2+ and Cr3+ adsorbed by S. horneri could be recovered from 0.1M HCl, 0.1M HNO3 and 0.1M EDTA by desorption process, and the efficiency of Pb2+ desorption was above 98%, whereas the efficiency of Cr3+ desorption was below 34%.

Marine algaes are capable of binding a large quantity of heavy metals. We have investigated the uptake capacity of Pb and Cu by using 22 species of marine algae, collected from Korean coast. Among a variety of different marine algae types for biosorbent potential, Kjellmaniella crassifolia showed the highest uptake capacity of Pb. Metal uptake of Pb and Cu by Kjellmaniella crassifolia increase as the initial concentration rises, as long as binding sites are remained. The metal uptake parameters for Pb and Cu had been determined according to Langmuir and Freundlich model. By increasing pH. Pb uptake was increased and Cu uptake was constant. The maximum uptake capacity of Pb and Cu by Kjellmaniella crassifolia was 437 ㎎/g and 129 ㎎/g, respectively.

The objective of this study was to examine the transient response to hydraulic shocks in an inverse fluidized bed biofilm reactor(IFBBR) for the treatment of apartment sewage. The hydraulic shock experiments, when the system were reached at steady state with each HRT 12, 7, and 4hr, were conducted by changing twice HRT per day during 3days. The SCOD, SS, DO, and pH of the effluent stream were increased with hydraulic shock, but easily recovered to the steady state of pre-hydraulic shock condition. In spite of hydraulic shock, there were not much variation of biomass concentration, biofilm thickness, and biofilm dry density.

Hydrodynamic characteristics such as gas holdup, liquid circulation velocity and bed expansion in a hexagonal inverse fluidized bed were investigated using air-water system by changing the ratio (Ad/Ar) of cross-sectional area between the riser and the downcomer, the liquid level(Hl/H), and the superficial gas velocity(Ug). The gas holdup and the liquid circulation velocity were steadily increased with the superficial gas velocity increasing, but at high superficial gas velocity, some of gas bubbles were carried over to a downcomer and circulated through the column. When the superficial gas velocity was high, the Ad/Ar ratio in the range of 1 to 2.4 did not affect the liquid circulation velocity, but the maximum bed expansion was obtained at Ad/Ar ratio of 1.25. liquid circulation velocity was expressed as a model equation below with variables of the cross-sectional area ratio(Ad/Ar) between riser to downcomer, the liquid level(H1/H), the superficial gas velocity(Ug), the sparger height[(H-Hs)/H], and the draft plate level(Hb/H). Uld=11.62g^0.75(Hl/H)^10.30(Ad/Ar)^-0.52(H-Hs/H)^0.91(Hb/H)^0.13