• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.56 no.6
• /
• pp.870-877
• /
• 2023

The purpose of this study was to assess the efficiency of nitrification based on ammonia loading rates and hydraulic air-loading rates in a moving bed bioreactor (MBBR) under seawater conditions. The goal was to provide foundational data for the design of these bio reactors. At an ammonia loading rate of 0.2 g TAN·m^-2 surface area·day^-1, the influent TAN concentration was determined to be 1.76±0.33 mg·L^-1, which is below the safe concentration for fish survival (2 mg·L^-1). Considering operational aspects, the optimal ammonia-loading rate was derived. Subsequently, experimental results for nitrification efficiency at the optimal ammonia-loading rate revealed that the optimum hydraulic air-loading rate was 1.8 L·air·m^-2 surface area·min^-1. This condition resulted in the lowest concentrations of TAN and NO₂-N in the influent water, thus establishing the optimal hydraulic air-loading rate. A regression equation was derived for the ammonia-removal rate (Y) based on the ammonia-loading rate (x) and expressed as a 0.5-order equation (Y=ax^0.5+b). Specifically, for TAN concentrations of 0-6 mg·L-1, the regression equation Y=0.1683x^0.5-0.13628, was established.

• Fisheries and Aquatic Sciences
• /
• v.2 no.1
• /
• pp.52-57
• /
• 1999

Air-drived rotating biological contactor (RBC) system, which is effective method in filtering performance, was tested for the nitrification capacity in a recirculating system. At ammonia concentrations between 0.029 and 0.528 mg/l, the effect of ammonia loading rate on ammonia removal rate at three different hydraulic loading rates could be defined by the following first­order regression models: Hydraulic loading rate of $14.8 m^3/m^3/day:\;y=39.2\times+3.4 (r^2=0.9137)$, Hydraulic loading rate of $26.5 m^3/m^3/day: y=53.3\times+4.0 (r^2=0.8686)$, Hydraulic loading rate of $37.3 m^3/m^3/day: y=58.4\times+4.2 (r^2=0.7755)$, where, $\times$ is ammonia loading rate (mg/l), y is ammonia removal rate $(g/m^3/day)$, The equations showed the optimal ammonia removal rate at the hydraulic loading rate of $26.5m^3/m^3/day$. Below the ammonia concentration of 2.72 mg/l, first-order regression models between ammonia loading rate and ammonia removal rate at three different rates of speed are defined as follows: Rotational speed of $0.75 rpm: y=28.5\times+4.7 (r^2=0.9143)$, Rotational speed of $1.0 rpm: y=33.6\times+8.4 (r^2=0.9534)$, Rotational speed of $2.0 rpm: y=28.9\times+3.6 (r^2=0.9488)$, where, x is ammonia loading rate (mg/l), y is ammonia removal rate $(g/m^3day)$. The equations show the ammonia removal rate at the rotational speed of 1.0 rpm is significantly higher than that at the rotational speed of either 0.75 rpm or 2.0 rpm (P<0.05).

• Journal of Korean Society on Water Environment
• /
• v.35 no.6
• /
• pp.567-573
• /
• 2019

DABF(Dissolve Air Flotation with Ball Filter) is developed as the DAF with the addition of a fiber ball at the lower part of the DAF. The DABF with a capacity of 4,500 ㎥/h was constructed at Gijang SWRO plant in Busan. Since the ball filter has high filtration rate, the loading rate of DABF was designed from 20 to 42 ㎥/h/㎡. When one DABF basin is in the back washing mode, the loading rate of other two DABF basins is increased to 42 ㎥/h/㎡. Turbidity at the BF outlet in DABF is <2 NTU at turbidity of 5-10 NTU at the BF inlet. If there is no algae bloom and turbidity is low in raw seawater, only BF in DABF is operated and meets <2 NTU at the BF outlet. Even if BF is operated at high hydraulic loading rates, no significant differential pressure increases and reduction in the turbidity removal rate is minimal in a day. Thus, DABF is the pre-treatment technology that provides stable water quality even with BF onlyoperation without DAF operation. Compared with the DAF, DABF requires additional facilities such as valves, piping, and drainage systems for backwashing the BF. But in terms of footprint and operating costs, DABF has more advantages than DAF. With DABF application, the load of the downstream filtration equipment is decreased so that the capacity of the filtration equipment can be reduced. Also, if the downstream filtration equipment is to be maintained the same regardless of DABF, the operating cost of DABF is less than DAF.

• Journal of Korean Society of Water and Wastewater
• /
• v.31 no.5
• /
• pp.415-419
• /
• 2017

In recent years there have been large increases in the hydraulic loading rates used to design dissolved air flotation (DAF) facilities for drinking water applications. High rate DAF processes are now available at loading rates of 20 to $40m^3/m^2{\cdot}h$. This research evaluated dissolved air flotation as a separation method for algae and organic compounds from water treatment plants. During the service period of 2016. 5. to 2017. 6., DAF pilot plants ($500m^3/day$) process has shown a constantly sound performance for the treatment of raw water, yielding a significantly low level of turbidity (DAF treated water, 0.21~1.56 NTU). As a result of analyzing the algae cell counts in the influent source, it was expressed at 100-120 cells/mL. In DAF treated water, the removal efficient of alge cell counts was found to be upto 90%. The stable turbidity and algae removal were confirmed by operating the high rate DAF process under the condition of the surface loading rate of $30m^3/m^2{\cdot}hr$.

• Journal of Korean Society of Water and Wastewater
• /
• v.34 no.6
• /
• pp.463-471
• /
• 2020

A 1,000 ㎥/d DAF(dissolved air flotation) pilot plant was installed to evaluate the performance of the floating process using the Nakdong River. Efficiency of various DAF operations under different conditions, such as hydraulic loading rate, coagulant concentration was evaluated in the current research. The operation conditions were evaluated, based on the removal or turbidity, TOC(total organic carbon), THMFP(trihalomethane formation potential), Mn(manganese), and Al(aluminum). Also, particle size analysis of treated water by DAF was performed to examine the characteristics of particles existing in the treated water. The turbidity removal was higher than 90%, and it could be operated at 0.5 NTU or less, which is suitable for the drinking water quality standard. Turbidity, TOC, and THMFP resulted in stable water quality when replacing the coagulant from alum to PAC(poly aluminum chloride). A 100% removal of Chl-a was recorded during the summer period of the DAF operations. Mn removal was not as effective as where the removal did not satisfy the water quality standards for the majority of the operation period. Hydraulic loading of 10 m/h, and coagulant concentrations of 40 mg/L was determined to be the optimal operating conditions for turbidity and TOC removal. When the coagulant concentration increases, the Al concentration of the DAF treated water also increases, so coagulant injection control is required according to the raw water quality. Particle size distribution results indicated that particles larger than 25 ㎛ showed higher removal rates than smaller particles. The total particel count in the treated water was 2,214.7 counts/ml under the operation conditions of 10 m/h of hydraulic loading rate and coagulant concentrations of 60 mg/L.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.42 no.4
• /
• pp.96-105
• /
• 2000

Field experiment was performed from August 1996 to December 1999 to examine the performance of constructed wetland system for wastewater treatment in rural area. The constructed wetland system was installed in Konkuk University and the effluent from septic tank of school building was used as an influent to the treatment basin. The treatment basin was composed of sand bed with planted reed. From August 1996 to June 1998 the hydraulic loading rate was fixed with about 15.63cm/day and theoretical detention time was 1.38 days, and from July 1998 to December 1999 the hydraulic loading rate was about 6.25cm/day and theoretical detention time was 3.5days. It worked continuously even during winter time, and the sewage flowed without freezing even when average daily air temperature was below -1$0^{\circ}C$. Average removal rate of BOD , COD, and SS was about 70%, T-P removal rate was about 50.8% , and T-N removal rate was 23.9%. The reason for poor T-N removal might be due to high influent concentration and short retention times. At the later years BOD and COD removal rates were increased , and SS and T-P removal rates did not change significantly , but T-N removal rates were decreased. The effluent of the wetland system often effluent water quality standards for sewage treatment plant, therefore, further treatment would be required if the effluent need to be discharged to the public water. Wetland system involves relatively large land area and could be suitable for rural area. Therefore, utilization of reclaimed sewage for agricultural purpose or subsequent land treatment is recommended as a ultimate disposal of sewage for agricultural purpose or subsequent land treatment is recommended as a ultimate disposal of sewage in rural area.

• Korean Journal of Environmental Agriculture
• /
• v.18 no.4
• /
• pp.310-315
• /
• 1999

The feasibility of an absorbent biofilter system was examined for rural wastewater treatment. Hydraulic loading rates varied from 50 to 250 cm/day. Effluent of the septic tank was fed into the absorbent biofilter, and small ventilation fan was provided to supply air at the rate of 250 L/min to aerate the biofilter. The biofilter system demonstrated high removal rates for $BOD_5$ and TSS at the loading rate of 150 cm/day, generally meeting the Korean effluent water quality standard of 20 mg/L applicable to both. The nutrient removal was less satisfactory than the results of $BOD_5$ and TSS, but it was within the expected range of biological treatment processes. Considering the abnormally high influent concentration of nutrients during the experiment, better performance results could have been obtained if ordinary domestic wastewater was used. The system performance was not significantly affected by the hydraulic loading up to 150 cm/day, which is far more than the loading limit of the sand filter systems. Maintenance requirement was minimal, and no problems with noise, odor, flies or sludge arose. Since the biofilter system can be operated at a distance, operation in remote rural area and multi-system connected to one control office might be advantageous to the rural area. Overall, considering the cost-effectiveness, stable performance, and minimum maintenance, the biofilter system was thought to be a competitive alternative to treat wastewater in Korean rural communities.