• Environmental Engineering Research
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• v.25 no.3
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• pp.400-408
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• 2020

Hydrodynamic study of Activated Sludge Process (ASP) is important to optimize the reactor performance and detect anomalies in the system. Residence time distribution (RTD) study has been performed using LiCl as tracer on a pilot scale aeration tank (AT) and ASP, treating the pulp and paper mill effluent. The hydraulic performance and treatment efficiency of the AT and ASP at different operating parameters like residence time, recycle rate was investigated. Flow anomalies were identified and based on the experimental data empirical models was suggested to interpret the hydrodynamics of the reactors using compartment modelling technique. The analysis of the RTD curves and the compartment models indicated increase in back-mixing ratio as the mean hydraulic retention time (MHRT) of the tank was increased. Bypassing stream was observed at lower MHRT. The fraction of dead zone in the tank increased by approximate 20-25% with increase in recycle rate. The fraction of the stagnant zone was found well below 5% for all performed experiments, which was under experimental error. The substrate removal of 91% for Chemical oxygen demand and 96% for Biochemical oxygen demand were observed for the ASP working at a hydraulic mean residence time 39 h MRT with a 20% recycling of activated sludge.

• KSBB Journal
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• v.21 no.4
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• pp.241-247
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• 2006

The present study was intended to examine a basic scheme to determine the biochemical oxygen demand(BOD) of livestock wastewater by means of six individual dissolved oxygen(DO) sensors and its multi-measurable meter. Maximal point of the first order time derivative of the DO difference between DO distribution of sterilized livestock wastewater and that of non-sterilized livestock wastewater, was considered as the oxygen uptake rate(OUR) of microorganisms in livestock wastewater, as determined to be 0.00074 mg $O_2/{\ell}{\cdot}sec$. The present study showed that there was a fair linear relationship(97.72%) between maximal OUR and BOD values of livestock wastewater, the latter being determined by classical Winkler azide method. It was thus concluded that the present multi-biosensor system might be applicable to an on-line system for measurement of BOD of livestock wastewater.

• The Journal of the Korea Contents Association
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• v.6 no.10
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• pp.1-8
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• 2006

The new system evaluating the pollution of the water quality for the branches of geum river using the fuzzy integral was proposed in this study. In this paper, the five individual factors, such as BOD(biochemical oxygen demand), COD(chemical oxygen demand), SS(suspended solids), T-N(total nitrogen), and T-P(total phosphorus) are selected. The measurement of fuzzy integral was determined depending on the degree of how they affect the pollution of water quality. The real values for the five factors measured and obtained from the branches of the geum river was normalized to ranging from 0 to 1. Finally, using the fuzzy integral, the degree of the pollution for the branches of geum river was expressed as the real numerical number. As a result, it appears that this approach can be proposed as the new system evaluating the pollution of the water quality for the branches of the geum river.

• Korean Journal of Veterinary Service
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• v.15 no.2
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• pp.215-225
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• 1992

To estimate pollution status of livestock wastewater on four piggeries and one abattoir in Taegu area, physicochemical water analysis such as pH, suspended solid(SS), biochemical oxygen demand(BOD) and chemical oxygen demand(COD), and bacteriological examinations such as number of total viable cells and number of coliform with or without antibiotic resistance were carried out. The results obtained were as follows : The pH values of raw sewage ranged from 9.0 to 7.2 that of the effluent treated was lowed to 5.6~7.7. The SS values of raw sewage ranged from 5,275ppm to 120ppm and those of the efflunet decreased to 162~30ppm. The BOD values of raw sewage ranged 6,200ppm to 120ppm and those of the effluent treated decreased to 111 ~80ppm. The COD values of raw sewage ranged from 5,725ppm to 298ppm and those of the effluent decreased to 137~76ppm. The total viable cells of raw sewage ranged from $8.5{\times}11^{11}$/ml to $9.9{\times}10^7$/ml, those of the effluent decreased to $5.6{\times}10^6{\sim}4.2{\times}10^8/ml.$ The total coliforms of raw sewage ranged from $5.5{\times}10^9$/ml to $1.3{\times}10^5$/ml, those of the effluent decreased to $3.6{\times}10^4ml{\sim}9.0{\times}10^6$/ml. The incidence of streptomycin resistant coliforms was the highest(1.8~66.7%), and followed by tetracycline(1.7~64%), kanamycin(9.3~50.l%), ampicillin(0.06~45.5%) and chloramphenicol(14.3~33.5%) to total coliforms of raw sewage. The incidence of antibiotic resistant coliforms of raw sewage in farms ranged from 3.4~66.7% and that of abattoir's was 0.06% to 14.3%. Antibiotic resistant coliform counts of raw sewage ranged from 1.3$\times$10$^{8}$ /ml to 3.9$\times$10$^3$/ml, those of the effluent decreased to $3.0{\times}10^1{\sim}2.3{\times}10^5/ml$.

• Journal of Korean Society of Water and Wastewater
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• v.36 no.2
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• pp.81-95
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• 2022

The present study was performed to investigate the effects of NH₃-N and nitrifying microorganisms on the increased BOD of downstream of the Yeongsan river in Gwangju. Water samples were collected periodically from the 13 sampling sites of rivers from April to October 2021 to monitor water qualities. In addition, the trends of nitrogenous biochemical oxygen demand (NBOD) and microbial clusters were analyzed by adding different NH₃-N concentrations to the water samples. The monitoring results showed that NH₃-N concentration in the Yeongsan river was 22 times increased after the inflow of discharged water from the Gwangju 1st public sewage treatment plant (G-1-PSTP). Increased NH₃-N elevated NBOD levels through the nitrification process in the river, consequently, it would attribute to the increase of BOD in the Yeongsan river. Meanwhile, there was no proportional relation between NBOD and NH₃-N concentrations. However, there was a significant difference in NBOD occurrence by sampling sites. Specifically, when 5 mg/L NH₃-N was added, NBOD of the river sample showed 2-4 times higher values after the inflow of discharged water from G-1-PSTP. Therefore, it could be thought other factors such as microorganisms influence the elevated NBOD levels. Through next-generation sequencing analysis, nitrifying microorganisms such as Nitrosomonas, Nitroga, and Nitrospira (Genus) were detected in rivers samples, especially, the proportion of them was the highest in river samples after the inflow of discharged water from G-1-PSTP. These results indicated the effects of nitrifying microorganisms and NH₃-N concentrations as important limiting factors on the increased NBOD levels in the rivers. Taken together, comprehensive strategies are needed not only to reduce the NH₃-N concentration of discharged water but also to control discharged nitrifying microorganisms to effectively reduce the NBOD levels in the downstream of the Yeongsan river where discharged water from G-1-PSTP flows.

• Journal of Korean Society on Water Environment
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• v.26 no.1
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• pp.96-103
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• 2010

In this work, the presence of nitrification biochemical oxygen demand (NBOD) frequently occurred in the sewer outflow in winter season was analysed by the COD fraction methods using the respirometry and process simulations with real operation data measurements and analysis. The activated sludge models applied in this process simulation were based on the ASM No.2d temp. models, published by International Association on Water Quality (IAWQ). The ASM No.2d model is an extension of the ASM No.2 model and takes into account of carbon removal, nitrification, denitrification and phosphorus removal. The denitrifying capacity of phosphorus accumulating organisms has been implemented in the ASM No.2d model because experimental evidence shows that some of the phosphorus accumulating organisms can denitrify. It was shown that the concentrations of autotrophs (X_AUT) in the secondary clarifier and the $NH_4-N$ of T-N increased in the presence of NBOD measurements. Because of the low temperature (average $8^{\circ}C$) and possible operational troubles, the outcoming autotrophs exhausted oxygen in the process of nitrifying $NH_4-N$.

• Environmental Engineering Research
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• v.19 no.1
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• pp.47-57
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• 2014

The aim of this paper was to study the effect of five different waste combinations (C/N 15, C/N 20, C/N 25, C/N 30, and control) of sewage sludge coupled with sawdust and cattle manure in a pilot scale rotary drum reactor, during 20 days of the composting process. Our results showed that C/N 30 possesses a higher temperature regime with higher % reduction in moisture content, total organic carbon, soluble biochemical oxygen demand and chemical oxygen demand; and higher % gain in total nitrogen and phosphorus at the end of the composting period implying the total amount of biodegradable organic material is stabilized. In addition, $CO_2$ evolution and oxygen uptake rate decreased during the process, reflecting the stable behavior of the final compost. A Solvita maturity index of 8 indicated that the compost was stable and ready for usage as a soil conditioner. The results indicated that composting can be an alternate technology for the management of sewage sludge disposal.

• Journal of the Korean Institute of Navigation
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• v.16 no.1
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• pp.37-64
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• 1992

A study on the changes of the oceanographical environment caused by Mokpo coastal zone development was carried out. Special emphasis was placed on the clarification of the water level changes and coastal current structure and influence of the environmental factors on the coastal area. In order to understand the structure oceangraphical environemnt, such as water temperature, salinity, suspended solids, pH, dissolved oxygen, chemical oxygen demand, biochemical oxygen demand, distribution of bottom sediment, tide and current were measured. To investigated the structure of tide and current for the future development, a numerical analysis was carried out. In certain zones, it was found to be flooding problems near the lowlying commercial area.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.4
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• pp.325-331
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• 2006

Various environmental conditions affecting total phosphorus removal from farm wastewater in a biofilm filter process were investigated using loess balls and Chromobacterium LEE-38 at a pilot plant. When Chromobacterium LEE-38 was used, the removal efficiency of total phosphorous was approximately 10- or 5-fold higher than that of Acinetobacter CHA-2-14 or Acinetobacter CHA-4-5, respectively. When a loess ball of $11{\sim}14mm$ manufactured at a $960^{\circ}C$ calcining temperature was used, the removal efficiency of total phosphorous was 90.0%. When 70% of the volume fraction was used, the maximum efficiency of total phosphorus removal was 93.1%. Notably, when the initial pH was in the range of 6.0 to 8.0, the maximum removal efficiency of total phosphorus was obtained after 30 days. When the operating temperature was in the range of 30 to $55^{\circ}C$, the maximum removal efficiencies of total phosphorus, 95.6 to 94.6%, were obtained. On the other hand, at operating temperatures below $20^{\circ}C$ or above $40^{\circ}C$, the removal efficiency of total phosphorous decreased. Among the various processes, biofilm filter process A gave the highest removal efficiency of 96.4%. Pilot tests of total phosphorus removal using farm wastewater from the biofilm filter process A were carried out for 60 days under optimal conditions. When Acinetobacter sp. Lee-11 was used, the average removal efficiency in the p-adsorption area was only 32.5%, and the removal efficiencies of chemical oxygen demand (COD) and biological oxygen demand (BOD) were 56.7 and 62.5%, respectively. On the other hand, when Chromobacterium LEE-38 was used, the average removal efficiency was 95.1%, and the removal efficiencies of COD and BOD were 91.3 and 93.2%, respectively.

• Environmental Engineering Research
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• v.23 no.1
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• pp.99-106
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• 2018

Lack of information on the Biochemical Oxygen Demand (BOD) decay rates of river water under the tropical environment has triggered this study with an aim to fill the gap. Raw sewage, treated sewage, river water and tap water were mixed in different proportions to represent river water receiving varying amounts and types of wastewater and fed in a laboratory flume in batch mode. Water samples were recirculated in the flume for 30 h and BOD and Carbonaceous BOD (CBOD) concentrations were measured at least six times. Decay rates were obtained by fitting the measured data in the first order kinetic equation. After conducting 12 experiments, the range of BOD and CBOD decay rates were found to be 0.191 to 0.92 per day and 0.107 to 0.875 per day, respectively. Median decay rates were 0.344 and 0.258 per day for BOD and CBOD, respectively, which are slightly higher than the reported values in literatures. A relationship between CBOD decay rate and BOD decay rate is proposed as $k_{CBOD}=0.8642_{k_{BOD}}-0.0349$ where, $k_{CBOD}$ is CBOD decay rate and $k_{BOD}$ is BOD decay rate. The equation can be useful to extrapolate either of the decay rates when any of the rates is unknown.