The object of this study is to feasibility assesment for co-digestion efficiency of food waste recycling wastewater(FWR) with thermal hydrolysis process dehydration cake (THP Sludge). As a result of THP pre-treatment experimental conditions to 160oC and 30 minutes, the solubility rate(conversion rate of TCOD to SCOD) of the THP sludge increased by 34%. And the bio-methane potential in the THP sludge increased by about 1.42 times from 0.230 to 0.328 m3 CH4/kg VS compared to the non-pre-treatment. The substrates of the co-digestion reactor were FWR and THP sludge at a 1:1 ratio. Whereas, only FWR was used as a substrate in the digestion reactor as a control group. The experimental conditions are 28.5 days of hydraulic retention time(HRT) and 3.5 kg VS/m3-day of organic loading rate(OLR). During the 120 days operation period, the co-digestion reactor was able to operate stably in terms of water quality and methane production, but the FWR digestion reactor deteriorated after 90 days, and methane production decreased to 0.233 m3 CH4/kg VS, which is 67% of normal condition. After 120 days of the experiment, organic loading rate(OLR) of co-digestion reactor was gradually increased to 4.5 kg VS/m3-day and operated for 80 days. Methane production during 80 days was evaluated to be good at the level of 0.349 m3 CH4/kg VS. As a result of evaluating the dehydration efficiency of the sludge before/after 150-180oC THP using a filter press, it was confirmed that the moisture content of the sludge treated before THP at 180oC was 75% and improved by 8% from 83-85% level. Therefore, it is expected that the co-digestion reactor of FWR and THP sludge will ensure stable treatment water quality and increase bio-methane production and reduction effect of dehydration sludge volume.

Ocean discharge of sewage sludge, which started in the year of 1993 in Korea, was stopped in the beginning of 2012, Landfill of sewage sludge was also prohibited in 2003 owing to public acceptance of the lanfill sites, and partially reopened in 2007 due to the necessity of organic component in sludge to produce methane gas. Sludge recycle ratio will increase in sewage sludge treatment by volume reduction and drying, and then recycle of the thermal energy as fuel in power plant and also material as raw material of cement. Several drying processes are compared with reasoning and an appropriate drying sequence is suggested.

하수슬러지의 퇴비화를 촉진할 수 있는 방안을 검토하기 위하여 2월 및 8월에 하수슬러지를 채취하여 생균수를 측정한 결과 하수종말처리장에서의 폐수처리시 유입수량 변동, 양이온성 polyacrylamide의 사용량 및 기후 변동을 포함하는 여러 조건의 변화에 따라 미생물 종과 미생물수의 변동이 많았으며, 미소후생동물의 종류 및 활동성도 계절에 따른 차이가 있었다. 양이온성 polyacrylamide가 미생물 생육에 미치는 영향을 조사한 결과 양이온성 polyacrylamide의 농도가 0.8% 이상일 때는 모든 균주의 생육이 저해되었으나 0.2% 이하에서는 균 생육에 지장을 초래하지 않았다. 하수슬러지의 퇴비화 과정중에 관여하는 미생물의 균종과 균수를 조사하고자 하였으나 미생물의 생태적 생리적 특성과 퇴비화의 일정한 상관관계를 도출할 수는 없었다. 그러나 유기물 함량과 bulking agent로 톱밥을 투여하였을 경우 미생물의 균종과 균수의 증가가 관찰되었다. 하수종말처리장의 폭기조 투입직전 활성슬러지, 폭기조내 활성슬러지, 하수슬러지와 bulking agent로 톱밥을 혼합처리하여 관찰한 결과 Fragilaria sp., Proales sp., Vorticella sp., Schizothrix sp., Anabaena sp., Zoothaminium sp., Epstylis sp., Arcella sp., Balantidium sp., Actinophrys sp., Synedra sp., Euglypha sp., Ulothrix sp., Anacystis sp., 및 Clostium sp. 등의 다양한 미소 후생동물이 관찰되었다. 특히 전기간에 걸쳐 Fragilaria sp., Proales sp., Vorticella sp. 몇 Schizothrix sp.가 관찰되었다. 슬러지 내에 존재하는 세균, 효모, 방선균, 곰팡이, 미세조류, 원생동물 및 하등동물은 하수슬러지의 퇴비화 또는 감량화 과정 중에 존재하여 공극의 확보와 같은 물리적인 퇴비화 촉진과 생물학적 분해작용에 의한 퇴비화 촉진 효과를 얻을 수 있을 것이다.

The dewatering characteristics of the sewage sludge was investigated through the experimental observations and model simulations. The activated sludge and the anaerobically digested sludge were examined for the dewaterability evaluation within the pressure range of $0{\sim}10^6N/m^2$. Modified Buchner funnel test and compression test by the consolidometer were conducted to evaluate average specific resistance, porosity, and moisture percentage of filter cake. Shirato's technique of compression-permeability test was followed for the pressure range lower than about $10^2N/m^2$. The flocculation effects on sludge dewatering was also examined for ferric chloride and polymeric flocculant. The application of hydrated lime which can be used for flue-gas desulfurization showed improved moisture percentage, and was thought to have positive feasibility in combined system of sludge dewatering and incineration. Determined characteristic constants were applied to Tiller's cake filtration model to simulate liquid pressure distribution and porosity distribution in cake. Model simulations showed a sharp drop of the porosity close to the cake-medium interface for the highly compressible material such as the activated sludge and the anaerobically digested sludge.

우리나라 유기성 폐기물처리의 가장 큰 비중을 차지하던 해양투기 방법이 폐기물 해양배출을 금지하는 런던협약으로 인해 2012년부터 해양투기가 전면 금지됨에 따라 안정적이고 지속적인 육상처리 시설이 요구되고 있다. 환경부는 폐기물 관리법으로 온실가스 발생 억제 및 재활용 촉진을 위하여 유기성 슬러지의 직매립을 금지하였다. 그동안 유기성 폐기물을 자원화하기 위한 방법으로 퇴비화 기술이 많이 연구되어 왔으나 여러 가지 문제점들이 야기되고 있다. 소각방법은 다이옥신과 같은 2차 오염의 우려가 있으며, 퇴비화 과정에서는 발생되는 악취로 인하여 민원이 잦아지고 결국 퇴비화 시설이 폐쇄되는 경우가 많았다. 우리나라에서 쓰이고 있는 퇴비화는 비 연속식 처리로 퇴비 원료(유기성 폐기물)의 제한적 처리와 퇴비화 활성에 요구되는 시간이 길어 부지요구도가 높은 문제, 불안정한 최종 생성물, 감량화 실패, 장시간 온도조절 및 공기주입으로 인한 에너지 소비증가로 상용화에 어려움이 많다. 본 연구에서는 강릉시 하수종말처리장에서 배출되는 하수슬러지를 대상으로, 초고온 호기성 발효과정을 통해 하수슬러지의 퇴비화 진행에 따른 온도변화, 발효가스 분석, pH, C/N비, 수분함량, 고형물 유기물 변화, 부피 및 무게변화, 중금속 분석, 혼합 및 교반과 같은 반응인자들을 도출하여 운전 변수를 알아보았다. 한편 하수슬러지의 퇴비화 진행에 따른 시료와 발효 종료된 퇴비의 중금속 및 유해인자 분석을 통하여 퇴비의 발효 메커니즘 및 안정성을 검증하였다. 초고온 퇴비화 기술의 새로운 정립과 국내 연구가 전무한 초고온 발효공정의 data base 확보를 목적으로 하였다. 또한 퇴비화 과정에서 발생되는 악취도와 악취를 발생시키는 원인물질을 밝히고자 하였다.

In this study, the effect of hydrogen peroxide (H2O2) pre-treatment for sewage sludge prior to anaerobic digestion wasassessed using a batch test with an objective to decrease nitrogen, dissolved sulfide and siloxane in sewage sludge. Atotal of 6 sets of experiments (Blank, 20, 40, 60, 80 and 100g H2O2/kg wet sludge) were carried out, each with duplicates.To assess the effect of different dosages of H2O2 on anaerobic digestion, the treated sewage sludge was used for biochemical methane potential (BMP) test and SCODcr concentration. Due to the H2O2 pre-treatment, solubilization of SCODcr in pretreated sludge increased by 89% compared to raw sewage sludge, whereas T-N and NH3-N concentrationdecreased. Cumulative methane yields were increased for all pretreated samples due to increased sludge solubilizationthrough H2O2 pre-treatment. In addition, dissolved siloxane concnetrations were decreased for all pretreated samples. Thus,a reduction in dissolved siloxane concenrtation can decrease the siloxane generation potential of sludge during anaerobicdigestion. However, dissolved sulfide concentration remained same. Although H2O2 dosage did not show any furtherimpact on dissolved sulfide, they have significantly decreased T-N, NH3-N and dissolve siloxane concentrations beforeanaerobic digestion.

T-N and T-P in the filtrate from Sludge Treatment Process (STP) was returned to water treatment processing, because T-N and T-P are returned, it makes overload in Advanced Treatment Process. Removal efficiency of T-N and T-P are compared both at using polymer as simple method and at using PFS and polymer as complex method when coagulants was injected in Thickener. In simple method, removal efficiency of T-N and T-P were 95.68% and 99.29% for each. In complex method, removal efficiency of T-N and T-P were 98.07% and 99.90% for each. From the result, removal efficiency of complex method was highly better than simple method. According to increasing of removal efficiency, returned T-N and T-P loading to water treatment process was decreased (Reduced amount of T-N is 0.2309 kg/hr and TP is 0.0145 kg/hr). Also, the amount of a polymer used has been decreased to 80% by using PFS.

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 ㎍/kg, dry wt..

The 16 priority PAHs (Polycyclic Aromatic Hydrocarbons) designated by US Environmental Protection Agency were analyzed for some digested sludges from wastewater treatment plants in Korea. PAHs are an important group of organic contaminants present in sewage sludge due to their persistence and toxic potential. PAHs were extracted from freeze-dried sludges using a methylene chloride-methanol (2:1) mixture in a soxhlet extractor. The extracts were cleaned-up by silica gel/alumina combination column and subsequently fed into gas chromatograph/mass spectrometer (GC/MS) for determining PAH contents. The sum of the 16 PAHs in the sewage sludge varied from 534.8 to 5754.5 ㎍/kg, dry wt.. In the sewage sludge, phenanthrene appears as the most abundant PAHs, followed by naphthalene, pyrene, fluoranthene. Source of the investigated sewage sludges relatively predominated pyrogenic. PAHs levels of sewage sludges in Korea appeared to be lower than those in other countries.

Polycyclic aromatic hydrocarbons (PAHs) are an important group of organic contaminants present in sewage sludge, due to their persistence, toxic, bioaccumulative and long range transfer. These characters make themselves as Persistent Organic Pollutants(POPs) in Long Range Transboundary Air Pollutions convention(LRTAP) of Europe. A method of the gas chromatographicmass spectrometric (GCMS) determination of PAHs present in sewage sludge was developed and applied to analyzed samples from five sewerage treatment plants (SWTPs), having different treatment types. PAHs were extracted from freeze-dried samples by toluene 16 hours in a soxhlet extraction system. The sludge extracts were cleaned-up by an activated silica gel column chromatography. The sum of the 16 US Environmental Protection Agency PAHs sewage sludge samples varied from 2.44 to 4.82 ㎍/ g. Concentration of emission carcinogen PAHs(PAHcarc), such as Benzo(a)anthracene, Benzo(b)fluoran- thene, Benzo(k)fluoranthene, Benzo(a)pyrene, Dibenzo(a,h)anthracene and Indeno(1,2,3-cd)pyrene ranged from 0.62 to 1.03 ㎍/g. The total amount of PAHs emission from sewage sludge in Korea was calculated as a top-down approach. PAHs and ∑PAHcarc from sewage treatment plants had emitted to environment by several pathway. The highest amount of emission to the environment was remarked in the ocean dumping(PAHs and ∑PAHcarc emissions were 1155.95 kg/year and 5040.32 kg/year, respectively).