Solid-liquid separation is important for securing safe runoff quality in the biological treatment process. In particular, the method for determining sludge settlement characteristics using SVI, which is a parameter, evaluates the precipitation features of sludge in an aeration tank and secondary precipitation tank and is a simple and widely used method. However, in methods using SVI, the accumulation of objective data is usually not possible, since the subjective judgment of operators is mainly involved in this evaluation method. Therefore, the automation of SVI measurement is required to improve the determination method of sludge settlement using SVI. In this study, an automatic measurement system of SVI using optics was developed. To evaluate the reliability of the measurement system, a visual inspection test was performed in parallel with our suggested SV30 auto-measurement system using actual sludge and a similar tendency in the results was obtained. Using this suggested SV30 automation system, the indirect determination of MLSS (Mixed-Liquor-Suspended-Solids) activation states of the aeration tank and precipitation tank is also expected to be possible. Through the test results, it was verified that the reliability of SVI determination was increased by identifying the effect of outside light after performing a test under external light interference.

Domestic sewerage treatment plant is operated by activated sludge method and its modified method by using microorganism. In most cases, a method of using microorganism is directly controlled by the operator based on individual judgment through factors of DO, pH and ORP. In addition, under aerobic condition in bioreactor, energy consumption including excessive air injection is learned to be somewhat plenty. In order to solve this problem, in most of the process, improvement of internal recycling and activated environmental factor of microorganism were researched extensively. However, as factors are changed depending on various conditions, it is not sufficient as an indicator of judgment. As such, a research on operation of bioreactor that measures metabolic change in short time by directly measuring activated condition of microorganism using NADH fluorometer is required in reality.It is considered that the method like this could supplement problem of energy consumption being occurred in the existing treatment method and operational optimization of bioreactor would be enabled by controlling optimal air volume. Therefore, in this study, in order to obtain optimal operational indicator of bioreactor, proper air volume control test was performed and through batch test and site evaluation, possibility of NADH sensor being utilized as operational control indicator of bioreactor is intended to be analyzed. In order to compare with measured value, DO, ORP that are operational control indicator of existing bioreactor were used. As MLSS concentration was increased through batch test, NADH value was increased and site evaluation also showed similar tendency to batch test. Resultantly, it could be confirmed that changing level of NADH fluorometer was a sensor that could measure bioreactor condition effectively and optimized scale of bioreactor is considered to be utilized.

By the strengthening of sewage treated quality law and the amount of sewage sludge every year is increasing in Korea. However, it is difficult to disposal of sewage sludge due to ocean dumping restriction. As an alternative to this, drying, incineration, anaerobic digestion etc. is applied, which is uneconomical in most be processed by the consumption of energy. In particular, anaerobic digestion technology has been installed in the sewage treatment 65 plats in Korea’s STP(sewage treatment plant). It is most of the digestion efficiency requires the application of improved technology to less than 50%. As an improvement technology for most anaerobic digester, ultrasonic, electronic beam, ozone etc. solubilization method using has been mainly used. Therefore, in this study, after the wet milling particles of sludge to subject the sludge that has not been decomposed in the digested sludge circulating fluid of anaerobic digestion, was let examine the characteristic at the time of ozonation. The size of the particles before and after the wet milling, which is the measurement at each 105.26 μm and 77.18 μm, solubilization rate is increased to 23.5%. When ozonation after wet milling using sludge is determined as possible to improve the efficiency.

2011년 말 기준 전국에 가동 중인 공공하수처리시설은 500 m³/일 이상이 505개소에 시설용량은 25,017,730 m³/일이고, 500 m³/일 미만은 2,858개소에 시설용량은 210,376 m³/일에 달한다. 이는 2003년부터 하수도 보급률 78.8%에서 해마다 약 3%씩 증가하여 2011년도 말에는 90.9%로 증가되고, 인구증가 등의 요인에 따른 것이다. 또한 매년 하수처리시설의 유입유량과 유입하수농도의 변화는 지속적으로 증가하고 있다. 하수처리시설의 주 처리방법은 고액분리와 용존성 물질의 고형화하는 방법이 주를 이루며 이외에도 산화의 방법, 필터에 의한 방법 등으로 수중의 오염물을 배제시킨다. 특히, 용존성 물질을 고형화 하는 과정에서 대부분 유기성 물질로 구성된 오염물을 미생물의 처리과정으로 처리가 되어 지는데, 이 때 하수처리시설에서 생물 반응조의 상태를 보기 위하여 대부분이 SVI를 측정한다. 이는 미생물의 상태를 간접적으로 확인하고, 후단 공정에서의 고액분리의 정도를 예측하는 중요한 방법으로 많이 활용되고 있다. 따라서 본 연구에서는 SV30의 측정방법에 대하여 높이에 따른 광원의 조사와 측정된 값을 인식 가능성에 대하여 실시하고자 하였다. 연구에 대상으로 사용된 슬러지는 경기도 안산시 A공공하수처리장의 생물반응조 내의 슬러지를 채수하여 실험에 사용하였으며, 이 때 사용된 슬러지의 TS는 3,428 mg/L, VS는 2,491 mg/L로 측정이 되었다. 광원으로 사용된 램프는 LED(White, Foryard Co. Ltd, Taiwan)으로 하단에서 최초 높이 20mm 정도를 제외하고 높이 17mm간격으로 20개를 설치하였다. 광원 검출기(Perkin Elmer Co., German)도 동일한 방법으로 설치하고 광원과 검출기 사이에 SV30을 실험하는 방법을 기준으로 1,000mL의 유리재질의 매스실린더를 사용하였으며, 광의 조사 및 검출의 외부 환경은 외란광이 존재하는 조건에서 실험을 실시하였다. 사용된 검출기의 특징은 외부 광원을 에너지로 인식하고 광원이 조사되면 저항(단위 Ω, R)이 내려가고, 광원이 차단되면 저항이 올라간다. 외란광의 환경에서 하부에서 상부로 갈수록 외란광의 차단효과가 적어져 메스실린더 내의 슬러지 투입전의 1,000 mL 위치에서 LED 램프 조사전은 4.78 kΩ, 0 mL에서 27.75 kΩ, 조사시는 1,000 mL 위치에서 3.49 kΩ, 0 mL에서 5.92 kΩ으로 측정이 되었다. 활성슬러지 투입시 압밀침전 전까지 슬러지 침강속도는 43.6 mm/min이었으며, 압밀침전의 속도는 3.58 mm/min으로 측정이 되었다. 이 때, 슬러지 계면이 있을 경우와 없을 경우의 측정차는 약 90 kΩ이상이 발생하여 슬러지 계면의 정도에 따른 측정이 가능할 것으로 판단된다.