• Journal of Korean Society on Water Environment
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• v.36 no.4
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• pp.322-331
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• 2020

By introducing chemically enhanced primary treatment (CEPT) in the first stage of sewage treatment, organic matter in sewage can be effectively recovered. Because CEPT sludge contains a high biodegradable organic matter in volatile solids (VS), it is feasible to convert the collected CEPT sludge into energy through anaerobic digestion. This study examined the properties and biochemical methane potential (BMP) of the CEPT sludge obtained from a sewage treatment plant located in an ocean area. The CEPT sludge contains a VS content of 37,597 mg/L, which is higher than that of excessive sludge (ES), i.e., 33,352 mg-VS/L. In the methane generation reaction, the lag period was as short as 1 to 2 days. The BMP for the CEPT sludge was 0.57 ㎥-CH₄/kg-VS_removed which is better than that of ES, i.e., 0.36 ㎥-CH₄/kg-VS_removed. Unfortunately, the CEPT sludge showed a high salinity as 0.56~0.75% probably due to the saline sewage. Due to the salinity, repeated BMP testing in a sequencing batch reactor showed significantly low methane production rates and BMPs. Also, the ES showed a strongly reduced BMP when the salinity was adjusted from 0.20 to 0.70% by NaCl. The ES mixture with higher CEPT content showed a better BMP, which is suitable for co-digestion. Besides, anaerobic digestion for 100% CEPT sludge can be a considerable option instead of co-digestion.

• Journal of Environmental Science International
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• v.15 no.3
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• pp.229-236
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• 2006

Organophosphorus pesticides (OPPs) contents in the sewage sludge derived from the residential and industrial areas were determined in order to characterize contemporary organic contamination levels as a part of the ongoing development of the environmentally sound sewage sludge management strategy in Korea. OPPs were extracted from freeze-dried sludges in a ultrasonic extractor. The extracts were cleaned-up by florisil column and subsequently fed into gas chromatograph/nitrogen phosphorus detector (GC/NPD) for determining OPP contents. Diazinon, dimethoate, disulfoton, EPN, malathion, methyl parathion, parathion, phorate and sulfotep were present in the appreciable amount in the domestic sewage sludges. The sum of the 9 OPPs in the sewage sludge varied from 534.8 to 15552.1 ${\mu}g/kg$, dry wt..

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.117-120
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• 2006

The purpose of this study is to efficiently treat the sewage sludge discharged from sewage treatment plants and evaluate the feasibility of the manufacture of lightweight aggregates(LWA) using a large quantity of sewage sludge. Sintered lightweight aggregate from sewage sludge is experimentally manufactured with various mass ratios of clay to sewage sludge by a pilot plant, and is tested for density, water absorption and crushing value. Their physical properties are compared to those of a commercial sintered lightweight aggregate. As a result, an experimentally manufactured lightweight aggregate is similar or superior in physical properties to the commercial lightweight aggregate. The manufactured lightweight aggregate could be used for structural concrete and non-structural concrete.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.6
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• pp.559-572
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• 2018

The aim of this study was to evaluate pretreatment methods for 27 pharmaceuticals and personal care products (PPCPs) in various sewage samples using a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) and online solid-phase extraction with LC-MS/MS. Extraction efficiencies of PPCPs in the solid phase under different experimental conditions were evaluated, showing that the highest recoveries were obtained with the addition of sodium sulfate and ethylenediaminetetraacetic acid disodium salt dehydrate in acidified conditions. The recoveries of target compounds ranged from 91 to 117.2% for liquid samples and from 61.3 to 137.2% for solid samples, with a good precision. The methods under development were applied to sewage samples collected in two sewage treatment plants (STPs) to determine PPCPs in liquid and solid phases. Out of 27 PPCPs, more than 19 compounds were detected in liquid samples (i.e., influent and effluent) of two STPs, with concentration ranges of LOQ-33,152 ng/L in influents and LOQ-4,523 ng/L in effluents, respectively. In addition, some PPCPs such as acetylsalicylic acid, ibuprofen, and ofloxacin were detected at high concentrations in activated sludge as well as in excess sludge. This methodology was successfully applied to sewage samples for the determination of the target compounds in STPs.

• Journal of Korean Society on Water Environment
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• v.29 no.2
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• pp.276-287
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• 2013

Domestic sewage contains increasingly more pharmaceuticals and personal care products (PPCPs), due to rising use of medicines, health supplement food and daily necessities. And various types of industrial wastewater from pollution sources in treatment areas could flow into the public sewerage treatment plants (PSTPs) in metropolitan areas. The conventional PSTPs are designed to treat suspended solids, biodegradable organics, nitrogen and phosphorous from residential and industrial areas and public facilities. However, toxic, conventional, and non-coventional pollutants from non-domestic sources that discharge into sewer system as well as domestic source with various chemicals could not be treated in the conventional PSTPs and discharged untreated to public basin. In this paper we aim to consider the establishment system of effluent standard of PSTPs in comparison with water quality standard of water environment and wastewater discharge regulation. And also we suggest the necessity of regulations on the pretreatment of industrial wastewater as part of efforts to improve water quality in sewerage systems and to protect public basin.

• Journal of Environmental Health Sciences
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• v.35 no.4
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• pp.334-342
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• 2009

Perfluorinated compounds (PFCs) have a wide range of domestic and industrial applications, but they are persistent in the environment. Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) are among the metabolites of PFCs and occur at high concentration in the environment. Korea is the largest importer of PFC compounds in the world, therefore, the accumulation of these compounds is possible. In this study, the concentrations of PFOS and PFOA were determined in water samples taken from sewage treatment plants (STPs) and the Han River in Seoul, Korea. After extraction with a HLB cartridge, PFCs in the samples were analyzed by HPLC with an ion trap mass spectrometry in electrospray negative mode. Limits of detection was between 1 and 1.6 ng/l. The result showed that the concentrations of PFOS and PFOA in effluent and influent of the four STPs in Seoul were 60~570 ng/l, and not detected (nd)~254 ng/l, respectively. The levels of PFOS and PFOA were higher in the effluents which passed through the treatment process than in influent water samples which was against expectation. The concentration of PFOA and PFOS in the Han River was 60~570 ng/l and nd~254 ng/l, respectively. PFOA was detected in every sample, but PFOS was only detected in the downstreams of the Han River. This result indicates that there is comprehensive contamination of PFCs in the aquatic environment in Korea.

• Journal of Korean Society of Water and Wastewater
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• v.36 no.2
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• pp.59-79
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• 2022

Conventional wastewater treatment plants (WWTPs) do not fully remove micropollutants. Enhanced treatment of sewage effluents is being considered or implemented in some countries to minimize the discharge of problematic micropollutants from WWTPs. Representative enhanced sewage treatment technologies for micropollutant removal were reviewed, including their current status of research and development. Advanced oxidation processes (AOPs) such as ozonation and UV/H₂O₂ and adsorption processes using powdered (PAC) and granular activated carbon (GAC) were mainly discussed with focusing on process principles for the micropollutant removal, effect of process operation and water matrix factors, and technical and economic feasibility. Pilot- and full-scale studies have shown that ozonation, PAC, and GAC can achieve significant elimination of various micropollutants at economically feasible costs(0.16-0.29 €/m³). Considering the current status of domestic WWTPs, ozonation and PAC were found to be the most feasible options for the enhanced sewage effluent treatment. Although ozonation and PAC are all mature technologies, a range of technical aspects should be considered for their successful application, such as energy consumption, CO₂ emission, byproduct or waste generation, and ease of system construction/operation/maintenance. More feasibility studies considering domestic wastewater characteristics and WWTP conditions are required to apply ozonation or PAC/GAC adsorption process to enhance sewage effluent treatment in Korea.

• Journal of Environmental Science International
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• v.8 no.1
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• pp.115-123
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• 1999

Sewage has been almost treated by secondary treatment process. Secondary-treated effluent of sewage treatment plant caused the pollution of nearby beach. Nitrogen(N) and Phosphorus(P) in effluent water have caused many problems on estuary, such as red tide, eutrophication and aquatic toxicity. Therefore, the effective nitrogen and phosphorus removal from sewage treatment plants is necessary to prevent those pollution problems. However, little sewage treatment plant in Korea is effectively being operated for the removal of the nutrients. This study is analyzed for the effectiveness of cost when tertiary treatment process and Ocean Outfall are applied for the water quality of Suyong Bay After secondary treatment process, the effluent was discharged from the seabed in the depth of 32m of 4000m offshore. Pollutant concentration is decreased as much as the 180 times after the result of initial dilution, so that environmental protection requirement of Suyong Bay can satisfied. This Ocean Outfall process can save the 2.6~3.5 times as much as the cost of construction and operation for tertiary treatment process running over a 20 year.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.1
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• pp.64-73
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• 1997

Most of the municipal wastewater treatment plants operated in Korea are designed for high concentrations municipal sewage. However, activated sludge process employed by municipal wastewater treatment plant is operated at low organic loading. The objective of this study was to determine optimum operating condition of activated sludge process for treatment of low concentration municipal sewage. Three bench scale activated sludge reactors were operated to investigate the effect of HRT and SRT on the COD and TSS removal efficiency. The average concentration of TSS, SCOD, SBOD and TKN in influent were 118mg/l, 61mg/l, 21mg/l, and 12mg/l, respectively. The activated sludge reactors operated with various HRT and SRT showed about 89-93% TSS removal efficiency. HRT and SRT does not affect the TSS removal efficiency of actvatied sludge process significantly. However, HRT affected the SCOD removal efficiency slightly. As the HRT decreases from 13hours to 3hours, the SCOD removal efficiency decreases from 67% to 56%. The average effluent TCOD concentration of the reactor operated with 3hours of HRT was approximatly 40-45mg/l. Kinetic coefficient yield (Yt) and decay coefficients(Kd) were 0.594-0.954 mgMLVSS/mgCOD and $0.0197-0.0317day^{-1}$, respectively. Low concentration municipal sewage can be treated with 3 hours of HRT without effluent quality deterioration and SRT does not affect the substrate removal efficiency at this operation condition.

• Journal of Environmental Health Sciences
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• v.31 no.1
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• pp.86-93
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• 2005

Because generally large amount of sludges are generated from the process of sewage and wastewater treatment, the management and controlment of those sludge has become a important issue in many researches. In this dissertation, we conducted the research to see the physico-chemical characteristics of sludges generated from various sources. Moisture of sludges were 81.5% in textile industries, 81.4% in frame metal industries, 80.7% in 1st metal industries. Volatile solid were 22.1% in hide · rubber industries, 21.9% in coke · petroleum industries. Fixed solid were 18.5% and 17.7% in the 1st metal industries and frame metal industries. High heating value by wet base were 1,850 kcal/kg in coke · petroleum industries, 1,220 kcal/kg in hide · rubber industries, but sludges from the 1st metal industries and frame metal industries were impossible to incinerate because most of those sludges were inorganic. The leaching test showed that hazardous materials was detected in nearly every kinds of sludges. Some of sludges from hide · rubber industries and frame metal industries exceeded the leaching criteria and so they were classified as specific wastes. And other sludges generated in sewage treatment plants or other industries was below the leaching criteria.