Earticle

Higher concentrations of MLSS(Mixed Liquor Suspended Solis) in BNR(Biological Nut-rient Removal) systems and stringent effluent suspended solid concentration requirements demand a good design practice for secondary clarifiers. Although SOR(Surface Overflow Rate) and SLR(surface Loading Rate) are commonly used in secondary clarifier design, these parameters do not reflect hydraulics and solid-liquid separation within clarifiers. In this paper, the Clari-2D model that can simulate hydraulic and MLSS settling behaviors was used to evaluate secondary clarifier design in P water reclamation plant in Gyeonggi province, S. KOREA. Three parameters in settling equation were experimentally defined : Vmax is 14.718 m/hr, K1 is 0.242 m3/kg and K2 is 20 m3/kg, respectively. Steady and dynamic state simulations were carried out to find a diurnal inflow effect on clarifier. Also, effects of chemical addition to enhance phosphorus removal were simulated. With chemical addition, the hourly maximum effluent SS(suspended solid) concentration was found 8.8 mg/L. This concentration meets the SS effluent requirement that is 10 mg/L.

본 연구에서는 우리나라의 분산지역 및 농촌마을의 하수처리를 위해 자연정화 고도처리 공법인 NEWS (Natural and Ecological Wastewater treatment System)를 적용하였다. 고친수성 biofilter를 사용하여 고형물질과 유기물질을 제거하였으며, 인공습지를 이용하여 영양물질을 제거하였다. 장지적으로 안정성을 갖으며, 부지면적과 효율 면에서 기계적인 공법과 경쟁할 수 있는 자연정화 고도처리공법을 개발하고자 고친수성 biofilter와 상하흐름형 인공습지를 조합하여 (NEWS)처리효과를 검토하였다. 본 처리시설을 적용한 결과 COD를 제외한 수질항목에서 높은 제거율을 나타내었다. Biofilter 유출수는 국내 수질기준을 만족시키지 못하였으나, 인공습지를 거쳐 처리된 최종 유출수는 수질기준을 만족시켰다. BOD, SS, TN, TP의 유입부하량과 제거량과의 관계를 회귀분석 한 결과 결정계수는 각각 0.998, 0.999, 0.919, 0.919로 매우 높은 상관성을 나타냈다. 동절기 효율저하의 문제점을 해결하기 위해 연구시설의 지붕을 투명 폴리카보네이트 글라스로 설치하여 난방을 하지 않는 온실을 도입하고, 12-2월 동안 겨울철 처리장 실내 ${\cdot}$ 외 온도차이를 측정한 결과 처리장실내온도가 실외 온도보다 최고 $20^{\circ}C$까지 높게 나타났다. 따라서 본 연구에서 개발한 자연생태학적 하수고도처리공법인 NEWS는 유기물질과 영양물질 처리공정을 분리하여 처리효율을 높일 수있으며, 국내의 분산지역 및 농촌마을의 하수처리에 적용가능성이 높을 것으로 판단된다.

The feasibility of the Natural and Ecological Wastewater treatment System (NEWS) was examined for rural wastewater treatment in Korea. The intermittent trickling biofilter with high hydrophilic filter media was used for pretreatment for suspended solids and organic pollutants. The subsequent constructed wetland with porous granule materials was used for promoting nutrient removal. The results show that the removal efficiencies of the system were high with respect to the water quality parameters except COD. Even if the effluent from the biofilter did not meet the guidelines for wastewater treatment plant effluent in Korea in terms of $BOD_5$ and TN, the final effluent of the system meets the guidelines us to good performance of the constructed wetland. The regression analysis between pollutant loading rate and removal rate indicated that the system could have stable removal for SS, $BOD_5$, TN, and TP in the given influent ranges. The analysis in the winter period indicated that the wetland covered with transparent polycarbonate glass had the statble performance during the winter period dus to increase of temperature inside the wetland without any heating system. With the stable performance, effective poilutant removal, low maintenance, and cost-effectiveness, the NEWS could be considered as an alternative treatment system for decentralized regions and rural communities in Korea.

This study was conducted to obtain basic data to evaluate the applicability of geopolymers as absorbers for suspended solids (SS) in rainwater. Geopolymer absorbers were prepared by integrated gasification combined cycle fused slag and Si sludge. The SS removal percentages were determined and compared on the basis of the porosity, size, and density of the absorbers. The maximum SS removal percentage of the geopolymer absorber with a density of 0.9 g/cm3 and pore sizes ranging from ~123 to 909 μm was 91.0%, which meets the standard value for commercial absorbers in Korea. Although the geopolymer absorbers had low densities and large pore sizes, the SS removal percentage did not increase as the density decreased; this is because of the resulting low compressive strength and high fracture rate, which typically leads to the formation of small particles and increases SS concentration in rainwater.