Small-scale Sewage Treatment Research Articles

Oxygen vacancy-rich β-Bi2O3/Bi2O2SiO3 Z-Scheme heterojunction: A strategy to enhance visible light-driven photocatalytic removal of ARB and ARGs

Oxygen vacancy-rich β-Bi2O3/Bi2O2SiO3 (BO/BOS) Z-Scheme heterojunction was prepared by hydrothermal method-assisted calcination. Under visible light, β-Bi2O3/Bi2O2SiO3 photocatalyst demonstrated superior photocatalytic efficacy in degrading antibiotics and antibiotic-resistant Escherichia coli (AR E. coli) compared to individual β-Bi2O3 and Bi2O2SiO3. The experimental results showed that BO/BOS-450 sample possessed the best photocatalytic activity against tetracycline (2 h, 80.8%), amoxicillin (4 h, 57.9%) and AR E. coli (3 h, 107.43 CFU·mL−1). BO/BOS-450 sample showed 91.8% electrostatic capture of AR E. coli in the bacterial capture experiment. In the antibiotic-resistant genes (ARGs) degradation experiment, BO/BOS-450 sample was able to bring the log10 (Ct/C0) value of tetA to -3.49 after 2 h. Oxygen vacancies (OVs) were verified through HR-TEM, XPS and EPR analyses. ESR experiments aligned with the quenching experiment results, confirming that the crucial active species were ‧O2- and h+ during photocatalytic sterilization. A small-scale sewage treatment equipment was designed for the effective removal of ARB from real water samples.

Small Scale Wastewater Treatment Method for Rainwater Garden Based on Photovoltaic Photocatalysis Technology

Conventional small-scale sewage treatment mostly adopts the principle of biological contact oxidation process, which has limited scope of application, low degradation rate of pollutants in sewage, and poor sewage treatment effect. Based on this, a new small-scale sewage treatment method was proposed by introducing photovoltaic photocatalysis technology and taking S sponge community in Ningnan County, Liangshan Prefecture as an example. First, hydrothermal method is used to prepare photocatalyst to provide basic guarantee for sewage treatment. Secondly, the rainwater garden model is simulated and designed to obtain the composition and content of small-scale sewage. On this basis, a rainwater garden photovoltaic photocatalytic water purification system is designed, which establishes an A/O integrated process by connecting the anoxic zone (A section) and aerobic zone (O section) in series to fully achieve the goal of sewage treatment. Experimental analysis shows that the new method can significantly improve the degradation rate of organic pollutants in rainwater garden wastewater, with a degradation rate of over 99% and a maximum degradation time of 10.97 seconds, indicating that the application effect of this method is good.

인구감소지역 소규모 하수처리장의 전력 소비 특성에 관한 연구

The purpose of this study is to provide basic data necessary for efficient operation of small-scale sewage treatment facilities in rural areas where population decline is expected to be serious in the future by investigating the power consumption characteristics of small-scale sewage treatment facilities in depopulated areas. As a result of calculating the power consumption (PCU) based on the water consumption by sewage treatment zone, the PCU was found to be in the range of 1.045 to 12.96 kWh/㎥. In addition, when the treatment capacity of the treatment facility was 50㎥/day or more, the PCU tended to decrease as the treatment capacity of the treatment facility increased. In addition, there was no clear correlation between the capacity of the treatment facility and the PCU when the capacity of the treatment facility was less than 50 ㎥/day. In addition, PCU showed a value of 1 or more except for one treatment plant, and about 43% of the treatment facilities showed a value of 1.5 or more, indicating that most treatment facilities were operated inefficiently in terms of energy. In the future, it is judged that the energy consumption efficiency of small-scale sewage treatment facilities will deteriorate further due to population decline, so it is necessary to prepare appropriate measures.

Expression of biomarkers connected to endocrine disruption in Cottus gobio and Salmo trutta fario in relation to sewage treatment plant-efflux and pesticides

The increasing efflux on a large scale of organic contaminants holding endocrine disrupting activity from sewage treatment plants produces detrimental biological effects to various fish species. However, the impact of small-scale sewage treatment plant-efflux in small river streams and narrow creeks is largely unknown. Extensive pesticide output especially in vineyards and orchards also causes adverse effects on the endocrine system of wildlife fish species inhabiting nearby rivers. To elaborate whether fish species and populations in the areas of interest were at risk of experiencing endocrine disruption, we identified different biomarkers related to endocrine disruption in Cottus gobio and Salmo trutta fario and applied this approach to selected Austrian freshwater streams pre and post sewage treatment plants and permanent cultures with extensive pesticide output in South Tyrol. Overall, mRNA expression levels of vitellogenin, estrogen receptor α and zona pellucida genes in wildlife fish, compared to a control population reared under constant conditions in the laboratory were significantly increased. Sewage-treatment plant efflux did not significantly affect the mRNA expression levels while extensive use of pesticides altered mRNA expression significantly in C. gobio. C. gobio and S. trutta fario display different levels of mRNA expression. Cadmium and copper concentrations in liver tissues varied but did not indicate significant levels of contamination. Our results demonstrate the presence of endocrine disrupting chemicals in the tested freshwater streams. We anticipate our study to be a starting point for further studies focusing on the effects of endocrine disrupting chemicals on individuals and populations. Especially the fact that the two selected species reveal highly different levels of mRNA expression levels is of interest when applying biomarker approaches which can be a useful tool for monitoring projects and risk-assessment associated studies.

소규모 하수처리장 유입 유량의 신뢰성에 관한 연구

To provide the basic data necessary to establish maintenance plans for existing sewage treatment plants in severely depopulated areas, the reliability of the inflow measurements for small-scale sewage treatment facilities was investigated. It was found that the population trends in sewage treatment districts and those in administrative districts did not coincide with each other, so the reliability of population-related data was very low. In addition, despite the low possibility of the inflow of water from unknown sources, more than 78% of the surveyed sewage treatment plants reported an inflow that was higher than the amount of tap water used within the treatment area. In particular, for sewage treatment plants with a capacity of 50 ㎥/day or less, the reliability of the flow rate measured using a flow meter installed in the sewage treatment plants was very low because the value calculated based on tap water consumption ranged from about 25% to 120% of the flow rate measured by the flow meter. These results indicate that, in small-scale sewage treatment plants where the reliability of the flowmeter is questionable, it is important to estimate the inflow rate based on the tap water consumption within the treatment area.

A Study on the Characteristics of Small-scale Sewage Treatment Plants in Mountain Area and Operation Plan for Winter Season

A Study on the Characteristics of Small-scale Sewage Treatment Plants in Mountain Area and Operation Plan for Winter Season

Optimal Selection of Sewage Treatment Technologies in Town Areas: A Coupled Multi-Criteria Decision-Making Model.

In recent years, the development of sewage treatment technologies has made many treatment options available in towns. Selecting the most appropriate alternative (MAA) can make the best use of existing resources to achieve the optimal effect, which has become a topical issue in academic circles. The Liao River basin in China is an important area for agricultural cultivation and animal husbandry, but it also suffers from water shortages and pollution. In this study, the fuzzy set theory (FST), the Analytic Hierarchy Process (AHP), and the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) were combined as a scientific and effective multi-criteria decision-making (MCDM) model to optimize the sewage treatment technologies in town areas of the Liao River basin. It was found that compared with natural treatment technologies (such as constructed wetlands, stabilization ponds, etc.) and combination technologies (i.e., a combination of various technologies), single small-scale sewage treatment plant technologies (such as activated sludge process or sequencing batch reactor with small daily capacity) were more suitable for those areas. The indicator of construction costs was critical in this model, and the fluctuation of its weight might change the MAA. This study aims to provide a decision support framework for the future optimization of sewage treatment technologies in towns by combining economic, environmental, and social issues, rather than just focusing on the technical aspects.

Experiences from wastewater treatment in the hilly areas in Sichuan

In recent years, measures have been taken against rural environmental problems, and remarkable achievements have been made in the construction of sewage treatment facilities, but there are still some problems. This paper takes three small sewage treatment facilities in the hilly areas of Sichuan as the research object, through field research and data collection, statistical analysis and analysis of various facilities, combined with actual use, the corresponding optimization development proposals are summed up to optimize the utilization efficiency of the facilities and improve the living environment in the rural areas. The results show that the combination of A2O+MBBR is more suitable for the economy and performance at Sichuan hilly areas, but other options can be selected according to different situations to achieve the best results. At the same time, this paper points out some problems and provides reasonable corresponding suggestions for rural small-scale sewage treatment facilities from the aspects of technical mode selection, planning and design, construction and operation, etc., and provides a more practical and feasible optimization plan and reference for the region to control rural water pollution.

Planning for achieving low carbon and integrated resources recovery from sewage treatment plants in Minas Gerais, Brazil

There is an enormous deficit in sanitation infrastructure in most Brazilian cities. To tackle this challenge, it is crucial to conceive the new sanitation infrastructure based on sustainability principles, including an integrated approach for the management of the liquid, solid and gaseous phases. This study aimed at developing sustainable sewage treatment flowsheets for different scales and regional scenarios in the state of Minas Gerais. Two watersheds were chosen as study areas, due to their remarkable regional importance and socioeconomic and environmental diversity, i.e. Rio das Velhas and Jequitaí-Pacuí. Currently available processes for sewage treatment and resources recovery were assessed based on: literature review and benchmarking of operational practices, experiences reported by sanitation companies, techno-economic feasibility of resource recovery and carbon footprint assessment of anaerobic-based technologies. Social acceptance was also considered. A total of 15 sustainable flowsheets were proposed, comprising passive/natural systems (stabilization ponds, constructed wetlands and controlled land application), anaerobic process combined with natural systems (UASB reactors followed by controlled land application, constructed wetlands or polishing ponds) and compact anaerobic/aerobic systems (UASB reactors followed by activated sludge or trickling filters). Processes selected for small-scale sewage treatment plants (STPs) (people-equivalent - PE < 10,000 inhab.) intended to be integrated into local communities and economic activities. Large-scale STPs (especially those with PE > 100,000 inhab.) were conceived as industries, where a wide range of resources (e.g. sand for non-structural concrete, biogas for electricity, sludge for thermal energy) could be recovered from the influent sewage. Results obtained from the current study could serve as support for decision-making on the planning and implementation of new sustainable sanitation solutions in the state of Minas Gerais and possibly in other regions of Brazil and other developing countries.

Application Study of small-scale sewage treatment system with A2/O precess in Mongolia

The small-scale sewage treatement system with A2/O process was applied to evaluate applicability for Mongolian sewage, It was designed to have 10 m3/d flowrate and installed in Ulaanbaatar, Mongolia. During over 6month operation BOD, COD, TN, TP removal efficiency were measured and operation condition was optimized. In addition, MLSS concentration its internal circulation rate and DO were adjusted properly. BOD, COD showed average 88 perecent of removal and TN and TP achieved 81 percent and 88 percent removal efficency, respectively. Maxium influent concentration of BOD, COD, TN and TP was 214 mg/L, 300 mg/L, 24.3 mg/L and 5 mg/L respectively, which were decreased to 4.1 mg/L, 5.6 mg/L, 1.3 mg/L and 0.15 mg/L by the test system. This study show possibility tham small-scale sewage treatment system could be a useful system for scattered sewage wastewater treatment.

경남지역 소규모하수처리시설의 효율적 운전관리방안 연구

경남지역 소규모하수처리시설의 효율적 운전관리방안 연구

Analysis of the performances of biogas-fuelled micro gas turbine cogeneration systems (MGT-CGSs) in middle- and small-scale sewage treatment plants: Comparison of performances and optimization of MGTs with various electrical power outputs

The suitable size (electricity output capacity) of micro gas turbine cogeneration systems (MGT-CGSs) depending on scale of the sewage treatment plant was investigated. Since heat demand of the plant is affected by ambient temperature, performance under three typical ambient temperature conditions was investigated. Considering operation of the MGT-CGS under various loads and efficiency of the MGT-CGS under a partial load condition, the optimal combination of MGT-CGSs (MGT-Combination) with different sizes, 30kW, 65kW and 200kW, was also proposed. An actual middle-scale plant was adopted as the analysis model, and it was scaled down to 0.50 and 0.25 in cases of smaller scale. Excluding MGT-Combination, it was found that the MGT that has approximately the same fuel energy input under full load as the biogas energy produced in the plant has the highest efficiency. However, in the case of heat demand of the plant varying throughout the year such as the operation in a cold region, partial load operation will be frequent and efficiency will decrease. Furthermore, MGT-Combination has the highest efficiency but its efficiency will be the same as that of the other MGT-CGSs when only comparatively constant operation is required throughout the year such as operation in a tropical region.

Removal of phosphate by the green seaweed Ulva lactuca in a small-scale sewage treatment plant (Ios Island, Aegean Sea, Greece)

In the present study, the use of seaweeds for phosphate absorption was examined as a tertiary treatment in sewage treatment plants, to improve the water quality and reduce eutrophication risks. The data came from both laboratory and field experiments that took place on Ios Island sewage treatment plant. Three different macroalgae were tested and Ulva lactuca was finally chosen thanks to its high survivability in low salinity waters. Since the main restrictive factor was low salinity, we initially established the ratio of seawater:effluent that combined satisfactory viability with maximum phosphate absorption. The biomass growth under these conditions was also examined. Based on the above results, we designed a continuous-flow system with a 1/4 volume per hour water turnover, in a mixture of 60% sewage effluent: 40% sea water and 30 g L-1 initial biomass of U. lactuca that must be renewed every 10 days. Under these conditions and time frame, the phosphate content of the effluent was reduced by about 50%.

자연정화공법에 의한 인공습지 하수처리장에서 하수처리 공정개선에 따른 질소 및 인의 처리효율 향상 방안

농어촌 등에서 소규모로 발생하는 하수를 자연정화공법 의한 인공습지에서 효과적으로 처리하기 위하여 소형 하수처리장치를 호기성조 및 혐기성조로 구분하여 시공한 다음, 최적 하수 부하량을 조사하기 위해 하수 부하량별 오염물질의 처리효율을 조사한 결과 호기-혐기 조합형 소형 하수처리장에서 전반적으로 하수 부하량이 증가함에 따라 오염물질의 처리효율이 점점 감소하는 경향으로 특히 하수부하량 300 <TEX>$Lm^{-2}day^{-1}$</TEX> 이상에서 수처리효율의 감소폭이 약간 컸다. 따라서 본 소형 하수처리장에서 BOD, <TEX>$COD_{Mn}$</TEX>, 탁도, T-N 및 T-P를 안정적으로 처리하기 위한 최적 부하량은 300 <TEX>$Lm^{-2}day^{-1}$</TEX> 이었고, 이 때의 방류수 중 BOD, <TEX>$COD_{Mn}$</TEX>, 탁도, T-N 및 T-P의 처리효율은 각각 99, 94, 99, 49 및 89%로 현행 방류수 수질기준을 만족하면서 안정적으로 처리되었다. 하지만 본 소형 하수처리장에서 방류수 중의 T-N 및 T-P 함량은 각각 <TEX>$28.5{\sim}29.4$</TEX> 및 <TEX>$0.9{\sim}2.1mgL^{-1}$</TEX> 정도로서 앞으로 질소와 인의 방류수 수질기준이 각각 20 및 2 <TEX>$mgL^{-1}$</TEX>로 강화됨에 따라 보다 안정적인 수처리를 위해서는 T-N 및 T-P 처리효율을 향상시켜야 할 것으로 판단된다. 이에 최적 하수 부하량하에서 질소와 인의 강화될 방류수 수질기준(질소 20 <TEX>$mgL^{-1}$</TEX> 및 인 2 <TEX>$mgL^{-1}$</TEX>)을 만족시키면서 안정적인 하수처리를 위한 최적의 수처리 공정개선 방안을 조사하였다. 호기-혐기 조합형 소형 하수처리장에서 수처리 공정개선 중 질소 및 인의 처리효율 향상이 가능한 방안은 혐기성조의 깊이 및 여재 입경 변경과 여재에 굴패각을 혼합한 방법이었다. 혐기성조의 깊이 및 여재 입경 변경 조건 중 혐기성조 1.5 m 깊이에서 여재 A(유효입경 1.50 mm)를 사용한 경우 T-N 및 T-P의 처리효율을 각각 10 및 3% 향상시켰고, 여재에 굴패각 혼합한 경우 T-N 및 T-P의 처리효율을 각각 14 및 7% 향상시켰다. 또한 동일한 조의 체적하에서 혐기성조의 깊이를1.5 m로 깊게한 것은 혐기성조 깊이 1 m에 비해 부지면적을 약 33% 정도 감소시킬 수 있을 것으로 판단되며, 또한 굴패각을 사용한 것은 폐기물의 재활용면에서도 매우 효과적인 방안으로 사용될 수 있을 것으로 판단된다. To effectively treat the domestic sewage that was produced on a small-scale in farming and fishing village in order to encourage an ecologically friendly environment, a small-scale sewage treatment apparatus using natural purification methods that consisted of an aerobic and an anaerobic plots were constructed. The efficiency of sewage treatment according to the sewage loading was investigated to obtain the optimum sewage loading in small-scale sewage treatment apparatus. Removal rate of pollutants according to the sewage loading were in the order of <TEX>$150\;Lm^{-2}day^{-1}{\fallingdotseq}300\;Lm^{-2}day^{-1}</TEX><TEX>></TEX><TEX>600\;Lm^{-2}day^{-1}$</TEX>. Therefore, the optimum sewage loading was 300 L m-2 day-1. Under the optimum sewage loading, removal rate of BOD, <TEX>$COD_{Mn}$</TEX>, turbidity, T-N and T-P were 99, 94, 99, 49 and 89%, respectively. However, to satisfy the water quality standard in effluent in small-sclae sewage treatment apparatus for domestic sewage treatment, the low removal efficiency of T-N and T-P must be improved. So to improve the removal rate of T-N and T-P, the efficiency of sewage treatment according to the improved sewage treatment process such as, re-treatment at aerobic plot, anaerobic condition of aerobic plot, changing the filter media sizes and the depths in anaerobic plot, and also addition of oyster shells to filter media at anaerobic plot were investigated. In case of 150 cm depth in anaerobic plot with filter medium A (effectivity particle size 1.50 mm) and addition of oyster shells to filter media at anaerobic plot, removal rate of T-N and T-P in both plots were increased by 10 and 3%, and 14 and 7% in comparison with 100 cm depth in anaerobic plot with filter medium B(effectivity particle size 0.95 mm), respectively. The optimum improved sewage treatment process in small-scale sewage treatment apparatus were 150 cm depth in anaerobic plot with filter medium A and addition of oyster shells to filter media at anaerobic plot.

자연정화공법에 의한 농촌 전원 독립가구 하수처리장치 개발

자연정화공법에 의한 농촌 전원 독립가구 하수처리공법 개발을 위하여 호기성조와 혐기성조가 분리된 소형 하수처리 장치에서 혐기성조 위에 호기성조를 포갠 일체형으로 공법을 개선한 소형 하수처리장치를 설계 및 시공하여 하수처리공법별, 하수 부하량 및 하수 주입방법에 따른 수처리 효율을 조사하였다. 소형 하수처리장치의 최적공법은 호기-무산소-혐기조건이었으며, 최적여재는 쇄석이었고, 최적 하수 부하량은 <TEX>$1,200L/m^3{\cdot}day$</TEX>이었다. 이러한 조건에서 농촌 전윈 독립가구에서 간헐적으로 배출되는 하수에 대한 대응성을 조사하기 위해 하수 주입방법에 따른 하수처리효율을 조사한 결과 농촌 전원 독립가구 하수처리공법으로 개발된 호기-무산소-혐기조건인 소형 하수처리장치는 실제 농촌 전원독립가구에서 간헐적으로 발생되는 하수에 그대로 적용하더라도 현행 방류수 수질기준인 BOD 20 mg/L, COD 40 mg/L, SS 20 mg/L, T-N 60 mg/L 및 T-P 8 mg/L을 만족할 뿐만 아니라, 방류수 수질기준이 앞으로 BOD 10 mg/L, T-N 20 mg/L 및 T-P 2 mg/L로 강화되더라도 안정적으로 처리될 수 있을 것으로 판단된다. 이상의 결과에서 농촌 전원 독립가구 하수처리공법으로 개발한 호기-무산소-혐기조건인 소형 하수처리장치는 BOD 99%, COD 95%, SS 99%, T-N 83% 및 T-P 96%초 질소 처리효율을 호기성조와 혐기성조가 분리된 소형 하수처리장치에 비해 17%정도 향상시켰으며, 모든 조가 일체형이므로 부지면적을 최소화할 수 있다. 따라서 본 공법은 자연정화공법의 단점을 보완할 수 있으므로 농촌 전원 독립가구에 적합할 것으로 사료된다. To develop small-scale sewage treatment apparatus for detached house of agricultural village, a small-scale sewage treatment apparatus by natural purification method that consisted of packaged form of aerobic, anoxic and anaerobic bed was constructed. The efficiency of sewage treatment according to the sewage treatment method, sewage loading, and the injection method of sewage were investigated for small-scale sewage treatment apparatus of packaged form of aerobic, anoxic and anaerobic bed. The removal rate of pollutants according to the sewage treatment method for small-scale sewage treatment apparatus was high in the order of aerobic-anoxic-anoxic bed < aerobic-anoxic-anaerobic bed. The optimum filter media in small-scale sewage treatment apparatus was a broken stone. The removal rate of pollutants according to sewage loading in small-scale sewage treatment apparatus was high in the order of <TEX>$1,200L/m^2{\cdot}day\fallingdotseq900L/m^2{\cdot}day\fallingdotseq600L/m^2{\cdot}day$</TEX>. The removal rate of pollutants according to injection method of sewage in small-scale sewage treatment apparatus was high in the order of continuous injection <TEX>$\fallingdotseq$</TEX> intermittent injection. When loaded under the optimum conditions, removal rate of BOD, COD, SS, T-N and T-P were 99, 95, 99, 83 and 96%, respectively, through this 3-stepped small-scale treatment apparatus arrayed with the order of aerobic, anoxic and anaerobic bed.

Development of Soil-covered SBR Process for Small Scale Sewage Treatment

Nitrogen and phosphorus compounds, mainly from the households in residential areas are responsible for eutrophication occurring in lakes or estuaries. In Korea, there is a growing trend for villages in the countryside, rest areas of express ways, military unit bases, etc. to use small scale sewage treatment plants (SSTPs). However, the technological developments have mainly focused on medium or large scale sewage treatment plants, leaving a gap in the development of technologies for SSTPs without a residing operator. In this study, a soil-covered sequencing batch reactor (SBR) process for SSTPs in combination with a natural purification technology is developed to remove nitrogen and phosphorus as well as organic contamination (BOD), and the results are as follows: (1) the removal rates of BOD, total nitrogen (T-N), total phosphorus (T-P) and suspended solids (SS) are 93%, 74%, 80% and 95%, respectively, (2) the soil-covered SBR process without the decanter used for effluent discharge is similar to other SBR processes in suspended solids removal rate, and (3) the performance of the field pilot plant was monitored by remote sensing system in real time, and the results show that this system can be applied to SSTPs with no residing operators.

자연정화공법에 의한 소형 하수처리장치 개발을 위한 최적 깊이 및 호기.혐기 비율

자연정화공법에 의한 농촌 전원 독립가구 하수처리장치의 적정 설치방법을 결정하기 위하여 호기성조와 혐기성조로 구성된 소형 하수처리장치를 설계 및 시공하였다. 소형 하수처리장치에서 여재 깊이에 따른 수처리 효율을 조사한 결과 호기성조와 혐기성조 모두 여재의 깊이가 깊어질수록 수처리 효율이 증가함으로 여재의 깊이를 90 cm이상으로 하는 것이 좋을 것으로 판단된다. 소형 하수처리장치의 최적 깊이인 90 cm하에서 호기성조 대 혐기성조 비율에 따른 수처리 효율을 조사한 결과 모든 여재에서 1 : 2 및 1 : 3의 호기 혐기 비율이 1 : 1에 비해 약간 높은 경향이었다. 따라서 소형 하수처리장치에서의 최적조건은 여재의 깊이는 90 cm이었고, 호기 혐기 비율은 1 : 2의 비율이었으며, 최적 여재는 왕사와 쇄석이었으며, 최적조건하에서 수처리효율은 BOD가 <TEX>$97{\sim}99%$</TEX>, COD가 <TEX>$87{\sim}97%$</TEX>, SS가 <TEX>$88{\sim}99%$</TEX>, T-N이 <TEX>$57{\sim}68%$</TEX> 및 T-P가 <TEX>$96{\sim}99%$</TEX>이었다. 따라서 이러한 조건을 자연정화공법을 이용한 하수처리장치에 적용하면 하수처리장치의 부지면적을 최대한 줄이면서 높은 하수처리효율을 유지할 수 있을 것으로 판단된다. To develop small-scale sewage treatment apparatus for detached house of agricultural village, a small-scale sewage treatment apparatus by natural purification method that consisted of aerobic and anaerobic bed was constructed. To reduce the area of a sewage treatment apparatus, four different fitter media were used and each filter medium was coarse sand, broken stone, steel slag, and mixed fitter media (coarse sand : broken stone : steel slag = 1:1:1). The efficiency of sewage treatment according to the depth of aerobic and anaerobic bed and the volume ratio of aerobic to anaerobic bed were investigated in small-scale sewage treatment apparatus. The removal rate of pollutants according to the depth of aerobic and anaerobic bed in small-scale sewage treatment apparatus was high in the order of 50 cm < 70 cm < 90 cm. The removal rate of pollutants according to the ratio of aerobic to anaerobic bed in small-scale sewage treatment apparatus was high in the order of 1:1 < 1:2 <TEX>$\fallingdotseq$</TEX> 1:3. Under the optimum conditions, removal rate of BOD, COD, SS, T-N and T-P were <TEX>$98{\sim}99,\;95{\sim}97,\;99,\;65{\sim}66\;and\;96{\sim}99%$</TEX> respectively, in small-scale sewage treatment apparatus.

Moving bed biofilm reactors: a small-scale treatment solution

The design and operational suitability of the moving bed process for small-scale sewage treatment systems were evaluated. A prototype plant was installed at a new housing development near Winchester, UK, and operated under different conditions over an eight-month period. During normal operation, the MBBR plant produced a good quality effluent with average values for BOD5, COD, SS and NH4-N of 15.6 mg l(-1), 65.9 mg l(-1), 21 mg l(-1) and 4.7 mg l(-1), respectively. The plant was further subjected to organic and hydraulic shock loads. The treatment performance remained high over the organic shock period, however, hydraulic surges of up to 10 times the design flow caused a loss of solids from the final settlement stage. While organic carbon removal resumed to over 80% within a single week after a prolonged power failure, effluent NH4-N values remained high for a period of three weeks. Besides producing a good quality effluent, the MBBR plant proved to be simple and reliable to operate, thus providing a viable treatment solution for small-scale applications.

자연정화공법에 의한 하수처리장에서 최적 여재 선정

An investigation was carried out to evaluate the effects of pebble size on the small-scale sewage treatment apparatus by natural purification method that consisted of aerobic and anaerobic plot. pH and EC in both plots varied minimally regardless of pebble size. DO in aerobic plot increased as the pebble size decreased. That in the anaerobic plot was slightly less in comparison with that of the aerobic plot but varied minimally, regardless of pebble size. Under all experimental conditions, removals of BOD, COD and turbidity in anaerobic plot were more than 98, 91 and 98, 98% respectively. Removals of T-N and T-P increased as pebble size decreased. Under all experimental conditions, removals of T-N and T-P in anaerobic plot were about and , respectively. Judging from the above results, it should be considered that the optimum pebble size and pebble permeability in both plot was and , respectively.

Small-scale sewage treatment plant

Small-scale sewage treatment plant