• Journal of Environmental Health Sciences
• /
• v.39 no.1
• /
• pp.83-89
• /
• 2013

Objectives: The purpose of this experiment was to illuminate the relationship between the phosphorus removal rate of unit operation and the phosphorus removal rate of phosphorus volume loading in the Ferrous Nutrient Removal process, which consists of an anoxic basin, oxic basin, and iron precipitation apparatus. Methods: This study was conducted in order to improve the effect of nitrogen and phosphorus removal in domestic wastewater using the FNR (Ferrous Nutrient Removal) process which features an iron precipitation reactor in anoxic and oxic basins. The average concentration of TN and TP was analyzed in a pilot plant ($50m^3/day$). Results: The removal rate of T-N and T-P were 66.5% and 92.8%, respectively. The $NH_3-N$ concentration of effluent was 2.62 mg/l with nitrification in the oxic basin even though the influent was 17.7 mg/l. The $NO_3$-N concentration of effluent was 5.83 mg/l through nitrification in oxic basin even though the influent and anoxic basin were 0.82 mg/l and 1.00 mg/l, respectively. The specific nitrification of the oxic basin ($mg.NH_3$-Nremoved/gMLVSSd) was 16.5 and specific de-nitrification ($mg.NO_3$-Nremoved/gMLVSSd) was 90.8. The T-P removal rate was higher in the oxic basin as T-P of influent was consumed at a rate of 56.3% in the anoxic basin but at 90.3% in the oxic basin. The TP removal rate (mg.TP/g.MLSS.d) ranged from 2.01 to 4.67 (3.06) as the volume loading of T-P was increased, Conclusions: The test results showed that the electrolysis of iron is an effective method of phosphorus removal. Regardless of the temperature and organic matter content of the influent, the quality of phosphorus in the treated water was both relatively stable and high due to the high removal efficiency. Nitrogen removal efficiency was 66.5% because organic matter from the influent serves as a carbon source in the anoxic basin.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.6
• /
• pp.1011-1019
• /
• 2000

The purpose of this study is to examine the basis of design condition of existing treatment processes, namely, Extended Aeration Process, Conventional Activated Process, High Rate Aeration Process and Modified Aeration Process, by clarifying the correlations of influent wastewater concentration, hydraulic retention time, food-to-microorganism ratio and sedimentation of sludge, as well as to ascertain the feasibility of design, regardless of the existing design condition. In particular, this study made a priority investigation of hydraulic retention time and sludge sedimentation, because sludge sedimentation is the main factor$^{1)}$ which determines the operating conditions of existing treatment processes. Therefore, it is generally known that in case exceeds the sphere of design presented for each treatment, sludge bulking may occur. The results of Lesperance's test$^{1)}$, which formed the basis of design, showed the sphere of loading without security of sludge sedimentation, as in Fig. 1. The reason for sludge bulking in a certain condition, as above, is due to failure in application of optimum loading corresponding to each retention time by employing a few operating condition, which proved to be consecutively workable after years of trials and failures by Lesperance, for test conditions. However, the result of this test showed that in case of proper maintenance of loading. sludge sedimentation can be ensured under 120 SVI. Therefore, this study suggested hydraulic retention time and its corresponding optimum loading, and identified the hydraulic retention time as a determinant of sludge sedimentation. And. on the basis of these findings, this study suggested the feasiblity of UHR(Ultra High Rate), a new operating process, exceeding several times the applicable loading value of High Rate Aeration Process under one hour retention time which has not yet applied to the existing treatment processes.

• Journal of Korean Society on Water Environment
• /
• v.23 no.4
• /
• pp.451-457
• /
• 2007

Four parallel $A^2/O$ systems maintaining an MLSS of 3,000 mg/L were operated to investigate the effects of varying an HRT of anoxic reactors and packing Bio contact media (BCM, fixed beds) in aerobic reactors on organic matter removal and nitrification/denitrification efficiencies. All systems were operated under conditions that the external recycle ratio was kept 0.5 Q while the internal recycle ratio was changed 1.0 Q to 1.5 Q with that $NH_4-N$ concentration of feed was increased to 40 mg/L by adding $NH_4Cl$. In terms of TSS and TCODcr removal efficiency, both systems with BCM and a system without BCM, respectively, had a similar level of the removal efficiency under varied HRTs of anoxic reactors (0.6 hr, 1.3 hr, 2 hr, 2 hr; control, without BC M) showing that varying an HRT of anoxic reactors did not affect the removal efficiency. While SCODcr removal efficiency of systems with BCM was improved approximately 4~5% at the same HRT of anoxic reactor, the removal efficiency of system with BCM was slightly decreased by reducing an HRT of anoxic reactor. The nitrification efficiency for both systems with BCM and a system without BCM was above 94% showing that packing BCM in aerobic reactors and varying an HRT of anoxic reactors did not affect the efficiency significantly despite of increasing $NH_4-N$ concentration of feed. The denitrification efficiency increased from 81.4% to 85.4% at system with BCM while the efficiency decreased when a shorter HRT of anoxic reactors was kept. The excellent effluent quality for $NO_3-N$ concentration was observed although the $NO_3-N$ concentration increased in anoxic reactors that $NH_4-N$ concentration of feed sufficiently converted into nitrate through nitrification. As a result, packing 20% BCM to an aerobic reactor with HRT of 1.3 hr of anoxic reactor in $A^2/O$ system can achieve a similar level of nitrogen removal efficiency in $A^2/O$ system which the aerobic reactor had no BCM and HRT of 2 hr for anoxic reactor is maintained.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.16 no.2
• /
• pp.57-65
• /
• 2008

Wastewater containing strong organic matter is very difficult to treat by utilizing general sewage treatment plant. but the wastewater is adequate to generate biomass energy (bio-gas; methane gas) by utilizing anaerobic digestion. EcoDays Plug Flow Reactor (E-PFR), which was already proved as an excellent aerobic wastewater treatment reactor, was adapted for anaerobic food wastewater digestion. This research was performed to improve the efficiency of bio-gas production and to optimize anaerobic wastewater treatment system. Food wastewater from N food waste treatment plant was applied for the pilot scale experiments. The results indicated that the efficiency of anaerobic wastewater treatment and the volume of bio-gas were increased by applying E-PFR to anaerobic digestion. The structural characteristics of E-PFR can cause the high efficiency of anaerobic treatment processes. The unique structure of E-PFR is a diaphragm dividing vertical hydraulic multi-stages and the inversely protruded fluid transfer tubes on each diaphragm. The unique structure of E-PFR can make gas hold-up space at the top part of each stage in the reactor. Also, E-PFR can contain relatively high MLSS concentration in lower stage by vertical up-flow of wastewater. This hydraulic flow can cause high buffering capacity against shock load from the wastewater in the reactor, resulting in stable pH (7.0~8.0), relatively higher wastewater treatment efficiency, and larger volume of bio-gas generation. In addition, relatively longer solid retention time (SRT) in the reactor can increase organic matter degradation and bio-gas production efficiency. These characteristics in the reactor can be regarded as "ideal" anaerobic wastewater treatment conditions. Anaerobic wastewater treatment plant design factor can be assessed for having 70 % of methane gas content, and better bio-gas yielding and stable treatment efficiency based on the results of this research. For example, inner circulation with generated bio-gas in the reactor and better mixing conditions by improving fluid transfer tube structure can be used for achieving better bio-gas yielding efficiency. This research results can be used for acquiring better improved regenerated energy system.

• Korean Journal of Environmental Agriculture
• /
• v.20 no.4
• /
• pp.289-296
• /
• 2001

The effects of HRT and effluent time on removals of pollutants in the electrochemical pilot were investigated. COD removal after 8 hour electrochemical reaction time in HRT 30 and 60 minutes were higher than that of 15 minute HRT. Turbidity removal was 90% or greater regardless of conditions during effluent time. Removals of T-N and T-P during effluent time in HRT 30 and 60 minutes were $71{\sim}74%$ and $85{\sim}98%$, respectively. To evaluate the combination of activated sludge process and continuous electrochemical as pretreatment, the removal efficiencies of pollutants was investigated. In two treatment processes of a single activated sludge system and a electrolysis pilot plus activated sludge systems, SVI and MLSS during effluent time were kept with $82{\sim}112$ and $1,230{\sim}1,750$ mg/L, respectively. COD removal was approximately 90% at early effluent time for both treatment systems, but COD removal in a single activated sludge was slightly decreased as effluent time went by, compared with the single activated sludge COD removal was slightly increased in the early stage of the electrolysis plus activated sludge system. Turbidity removal during effluent time was higher than 95% for both treatment systems. T-N removals during effluent time in a single activated sludge system and a electrolysis pilot plus activated sludge systems were $62{\sim}74%$ and $72{\sim}86%$, respectively. T-P removal in a electrolysis pilot plus activated sludge systems was increased by 9% at early effluent time and 15% after 72 hours of effluent time in compared with a single activated sludge system.

• Korean Journal of Microbiology
• /
• v.51 no.4
• /
• pp.374-381
• /
• 2015

Occurrences of coastal dredged materials are ever increasing due to port construction, navigational course maintenance and dredging of polluted coastal sediments. Ocean dumping of the coastal dredged materials has become virtually prohibited as London Treaty will be enacted as of the year 2012. It will be necessary to treat and recycle the dredged materials that may carry organic pollutants and heavy metals in a reasonable and effective process: collection of the dredged materials, liquid and solid separation, and treatment of organic compounds and heavy metals. In this study we have developed a continuous bioreactor system that can treat a mixture of silt and particulate organic matter using a microbial consortium (BM-S-1). The steady-state operation conditions were: pH (7.4-7.5), temperature ($16^{\circ}C$), DO (7.5-7.9), and salt concentration (3.4-3.7%). The treatment efficiencies of SCOD, T-N and T-P of the mixture were 95-96%, 92-99%, and 79-97%. The system was also effective in removal of heavy metals such as Zn, Ni, and Cr. Levels of MLSS during three months operation period were 11,000-19,000 mg/L. Interestingly, there was little sludge generated during this period of operation. The augmented microbial consortium seemed to be quite active in the removal of the organic component (30%) present in the dredged material in association with indigenous bacteria. The dominant phyla in the treatment processes were Proteobacteria and Bacteroidetes while dominant genii were Marinobacterium, Flaviramulus, Formosa, Alteromonadaceae_uc, Flavobacteriaceae_uc. These results will contribute to a development of a successful bioremediation technology for various coastal and river sediments with a high content of organic matter, inorganic nutrients and heavy metals, leading to a successful reuse of the polluted dredged sediments.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.3
• /
• pp.271-277
• /
• 2008

The biofilm of white-rot fungi fully exposed in atmosphere are that operation is easy, management cost and energy waste is low. To develop biofilm of white-rot fungi fully exposed in atmosphere, basic test are as follows. To select most effective microoganism species, investigated treatment characteristics of wastewater containing non-biodegradable material for three species of white-rot fungi(Phanerochaete chrysosporium PSBL-1, Phanerochaete chrysosporium KCTC 6147, Trametes sp. KFCC 10941) and activated sludge. And then investigated attached and detached biomass of selected white-rot fungi species on HBC ring surface. Among the three strains tested, P. chrysosporium PSBL-1 and P. chrysosporium KCTC 6147 showed higher efficiency for organics removal than Trametes sp. KFCC 10941, and P. chrysosporium PSBL-1 showed higher efficiency for nitrogen removal than P. chrysosporium KCTC 6147 and Trametes sp. KFCC 10941. Respectively, 51$\sim$59.8%, 57.5$\sim$60.3% of NBDCOD was removed for P. chrysosporium PSBL-1 and P. chrysosporium 6147 in pH 3.5$\sim$5.5. TN removal efficiency showed 39.3$\sim$85.3%, 3.4$\sim$7.6% for P. chrysosporium PSBL-1 and P. chrysosporium 6147 in pH 4.5$\sim$11.5 respectively. Considered that white-rot fungi remove organism and nitrogen simultaneously, the microorganism selected white-rot fungi P. chrysosporium PSBL-1. White-rot fungi P. chrysosporium PSBL-1 attached on HBC ring surface 4,538 mg/L, 4,546 mg/L, 4,531 mg/L after 5 minutes, 4,575 mg/L, 4,573 mg/L, 4,568 mg/L after 10 minutes from initial MLSS 4,600 mg/L in pH 4, 7 and 10 respectively. Also detached biomass is negligible from right after attachment to 10 day in pH 4, 7 and 10.

• Journal of Marine Life Science
• /
• v.7 no.2
• /
• pp.196-204
• /
• 2022

This study observed changes in survival, growth performance and water quality for 90 days to confirm the possibility of Leiocassis ussuriensis farming using Biofloc technology (BFT) using Bacillus subtilis. Feed and molasses were added to the experimental tank to produce BFT water before planting the experiment, and B. subtilis was inoculated to stabilize the water quality for 40 days. The survival rate of the experimental fish was 92.7±3.2% in the control group and 95.8±3.3% in the BFT group. The Weight gain (WG) was 118.1±9.0% of the control and 197.7±15.6% of the BFT, and the Specific growth rate (SGR) was 0.87±0.5% of the control and 1.21±0.06% of the BFT. As for the feed efficiency, the control was 43.7±2.6% and the BFT was measured at 70.1±4.1%, indicating that the feed efficiency of the BFT was higher. As a result of measuring the water quality change during the experimental period, pH was reduced in both the control and the BFT, and Mixed Liquor Suspended Solids (MLSS) did not show any change in the control, but the BFT showed a significant increase at 90 days. NH₄⁺-N and NO₂^--N showed a significant increase from the 30 days of the experiment in the control, but showed no change in the BFT. In conclusion, as a result of applying the BFT system using B. subtilis to the process of cultivating Leiocassis ussuriensis, the water quality tended to stabilize, and the growth rate and feed efficiency were found to be higher than those of the control, confirmiWng that it had a positive effect.