Small Treatment Plants Research Articles

농촌 지역에서 유입 유량이 소규모 하수처리장 처리 효율에 미치는 영향

농촌 지역에서 유입 유량이 소규모 하수처리장 처리 효율에 미치는 영향

The INCA-Pathogens model: An application to the Loimijoki River basin in Finland

Good hygienic quality of surface waters is essential for drinking water production, irrigation of crops and recreation. Predictions of how and when microbes are transported by rivers are needed to protect downstream water users. In this study we tested the new process-based INCA-Pathogens model in the agricultural Loimijoki River basin (3138km2) in Finland, and we quantified ecosystem services of water purification and water provisioning for drinking and recreation purposes under different scenarios. INCA is a catchment scale process based model to calculate pollutant transfer from terrestrial environment and point sources to the catchment outlet. A clear gradient was observed in the numbers of faecal coliforms along the River Loimijoki. The highest bacterial counts were detected in the middle part of the main stream immediately after small industries and municipal sewage treatment plants. In terms of model performance, the INCA-Pathogen model was able to produce faecal coliform counts and seasonality both in the low pollution level sampling points and in the high pollution level sampling points. The model was sensitive to the parameters defining light decay in river water and in soil compartment, as well as to the amount of faecal coliforms in the manure spread on the fields. The modeling results showed that the number of faecal coliforms repeatedly exceeded 1000 bacteria 100ml−1. Moreover, results lead to the following conclusions: 1) Climate change does not cause a major threat to hygienic water quality as higher precipitation increases runoff and causes diluting effect in the river, 2) Intensification of agriculture is not a threat as long as animal density remains relatively low and environmental legislation is followed, 3) More intensive agriculture without environmental legislation causes a threat especially in tributaries with high field percentage and animal density, and 4) Hygienic water quality in the River Loimijoki can best be improved by improving sewage treatment. We conclude that this catchment scale model is a useful tool for addressing catchment management and water treatment planning issues.

SEWAGE TREATMENT PLANT SINGLE FAMILY

Currently there is great concern about the lack of drinking water in the world, today Brazil has already suffered the consequences by waste and improper disposal of waste, suffering already with several forced rationing. Improper disposal of sewage is the main cause of soil pollution, groundwater, surface water sources and water courses in Santa Catarina. Among the existing municipalities in the state, only 8% are met with services by the sewage system, while the national average is 19%. More efficient existing sewage treatment systems are extremely large, with this in order to solve the problems with the incorrect disposal of sewage, as well as an efficient and cost-effective treatment, a small health treatment plant was designed, to meet families of up to 4 residents with similar price to the notch filter system, but more efficiently, allowing direct discharge into storm beds, even the reuse of water for irrigation systems. The prototype was installed on 10.8.2014, and performed all tests ordered by law to date. The results were encouraging, given both technical and financial.

Physical Processes Contributing to Localized, Seasonal Hypoxic Conditions in the Bottom Waters of Smithtown Bay, Long Island Sound, New York

ABSTRACT Swanson, R.L.; Bauer, C.L.; Wilson, R.E.; Rose, P.S., and O'Connell, C., 2016. Physical processes contributing to localized, seasonal hypoxic conditions in the bottom waters of Smithtown Bay, Long Island Sound, New York. Summertime hypoxia regularly occurs in the bottom waters of Smithtown Bay, Long Island Sound, New York. Hypoxia is plaguing many coastal estuaries and can be detrimental to aquatic organisms. A generally accepted model for the cause of coastal hypoxia in temperate regions is seen in the introduction of anthropogenic nutrients, which fuels excessive primary production, leading to oxygen depletion exacerbated by seasonal water-column stratification. No major point sources of anthropogenic nitrogen discharge directly into the bay. Groundwater nitrogen discharge is somewhat more than double that of a small sewage treatment plant. Despite great efforts to reduce nitrogen loading into Long Island Sound, summertime hypoxia is a continuing occurrence in Smithtown Bay. Hydrographic cruise...

Resource recycling with algal cultivation: environmental and social perspectives

Efficient use and recycling of resources by utilizing nutrients of waste water and CO2 from flue gases are considered through comparing two conceptual systems: a conventional small scale waste water treatment plant (base case) and a waste water treatment plant combined with algae cultivation unit (algae case). The used algae case concept is based on interviews of experts working with algae cultivation in Finland. Hotspots related to the algae case are assessed from environmental perspectives. According to model calculations, in high latitudes effective algae production may be achieved, although the areal production rates are very low in winter. In the algae case concept nutrients of waste water can be more effectively recycled using bio-based chitosan as flocculant. Also energy is produced in the biogas production plant, which increases the resource recycling of the algae case. When considering the energy balance, a positive net energy ratio (NER) >1 is possible to achieve with maximum methane production potential of algal biomass.

Tolerance to Ammonia of Thulinius ruffoi (Bertolani, 1981), a Tardigrade Isolated from a Sewage Treatment Plant.

The acute toxicity of ammonia on Thulinius ruffoi (Bertolani, 1981), a eutardigrade isolated from a small waste water treatment plant (WWTP) in Poland, was estimated. Our results show that no active individuals survived a 24 h exposure to solutions equal to or higher than 125 mg/L of total ammonia nitrogen (NH3–N + NH4+–N), which, under the conditions in our experiment, was equivalent to 1.17 mg/L of un-ionised ammonia (NH3). The LC50 concentration of total ammonia nitrogen was equal to 52 mg/L (or 0.65 mg/L un-ionised ammonia). Given that the norms for the concentration of ammonia in treated waters leaving WWTPs are usually several times lower than the LC50 for T. ruffoi, this species does not seem to be a good bioindicator candidate for WWTPs. In this paper we also note that various ecotoxicological studies use different methodological approaches and we suggest that a more uniform methodology may aid interspecific comparisons of LC50 values.

Presence of antibiotic resistance genes in a sewage treatment plant in Thibodaux, Louisiana, USA

Increasing uses and disposals of antibiotics to the environment have increased emergence of various antibiotic resistance. One of the sources for the spread of antibiotic resistance is wastewater treatment plant, where bacteria and antibiotics can come in contact and can acquire antibiotics resistance. There are very few studies on this subject from a small town sewage treatment plant. Therefore, this study was conducted using raw sewage as well as treated sewage from a sewage treatment plant in Thibodaux in rural southeast Louisiana in USA. Samples were collected monthly from the Thibodaux sewage treatment plant and the presence of antibiotic resistance genes was monitored. The study showed the presence of antibiotic resistance genes in both raw and treated sewage in every month of the study period. The genetic transformation assay showed the successful transformation of methicillin resistant gene, mecA to an antibiotic sensitive Staphylococcus aureus, which became antibiotic resistant within 24h.

Evaluating air-blown gasification for energy recovery from wastewater solids: Impact of biological treatment and point of generation on energy recovery

Decentralized water reclamation is emerging as a new paradigm that pairs local wastewater resources with local users; however, one of the challenges that must be addressed to advance its implementation is the low energy efficiency associated with small treatment plants and the lack of available small-scale energy recovery technologies. Gasification is a technology that could be used to convert wastewater solids to energy at small wastewater resource recovery facilities (WRRF). A model developed for air-blown gasification coupled with internal combustion engine for energy production demonstrated that gasification of wastewater solids could produce up to one third of the electrical demand at a small WRRF. Results based on samples collected from local wastewater treatment plants show that the energy embedded in wastewater solids does not vary substantially with treatment processes implemented or point of solids generation, and thus gasification is feasible for a wide variety of WRRF sizes and processes. Further modeling revealed that feedstocks generated by three different processes have similar power output for one metric ton per day of solids gasified (∼20kW), but the net power produced by a 19ML/dWRRF varies more substantially (110–140kW) because the mass of solids produced vary with each treatment scheme.

Research on Operation Mechanism and Application in Engineering of UNITANK Process

UNITANK is a new wastewater treatment technology combining the advantages of Sequencing Batch Reactor, normal aeration tank and 3-ditch oxidation treatment systems. It has been considered as an attractive pathway to be applied in small or middle wastewater treatment plants. It was chosen as the main process in Xingtai Wastewater Treatment Plant, Hebei Province, PR China. In this paper, the operation process, operation mechanism and features of UNITANK process were discussed in detail on the basis of the basic structure and the application in engineering.

소규모하수처리시설의 이차침전조 내통길이 변화를 통한 탈수여액의 처리

The purpose of this study is to evaluate a de-watering filtrate treatment and the possibility of securing biological treatment capacity by changing the structure of the secondary clarifier. Accordingly, the column test was conducted to determine the effect of polymer in the de-watering filtrate on sludge sedimentation. Also, the characteristics of de-watering filtrate processing was evaluated through batch test and continuous processing operation. The results showed that sludge settling velocity increased with higher polymer concentration, and that effluent SS concentration was found to decrease. Regarding processing characteristics of de-watering filtrate, the removal efficiency of TSS and TBOD5 increased as the length of secondary clarifier was longer. Also, comparing injections into anoxic tank and secondary clarifier, de-watering filtrate by continuous infusion treatment process showed stability in both conditions. Therefore, by modifying the structure of secondary clarifier, efficient processing of de-watering filtrate is expected to be possible and processing capacity of small sewage treatment plants is considered to be improved.

Comparison of carbon footprints and eutrophication impacts of rural on-site wastewater treatment plants in Finland

In many sparsely populated areas, such as the Finnish countryside, most houses are not connected to centralized sewers due to excessive distances. On-site wastewater treatment plants are therefore necessary to reduce local emissions to meet the legislatory limits. Dozens of on-site wastewater treatment applications are marketed to households, with varying operating costs and pollution reduction potentials. The installation and use of these systems will cause environmental impacts outside the site, through their supply chains. The aim of this study is to analyze the potential tradeoff between the reduction of local emissions and the increase in life cycle impacts. Six alternatives were chosen for comparison, including the energy-demanding small sewage treatment plants and the various types of soil systems (including source separation systems). The results show that the dry toilet in combination with gray-water treatment had the least impact and the package plants the greatest. However, which is the optimal on-site system solution for a certain property is strongly dependent on the local conditions and, therefore, appropriate guidance is definitely needed.

소규모 수도시설의 역삼투(RO), 나노여과(NF), 전기흡착(EA), 전기응집(EC) 공정의 질산성 질소 및 불소 이온 제거 성능 비교

소규모수도시설에서 수질기준을 자주 초과하는 질산성질소(NO3-N)와 불소(F-)를 제거하기 위해 역삼투(RO), 나노여과(NF), 전기흡착(EA), 전기응집(EC) 공정을 비교평가 하였다. RO는 질산성질소 72~92%, 불소 74~85%의 제거율을 나타내었고 NF는 질산성질소 5~15%, 불소는 1%의 제거율을 나타내었다. MWCNT를 코팅한 전극을 이용한 EA의 질산성질소는 99%, 불소는 44% 제거율을 보였다. 구리와 MWCNT 복합물 소결전극을 이용한 EA의 질산성질소는 82%, 불소는 77%의 제거율을 보였으나 구리가 용출되는 문제점이 발견되었다. EC의 질산성질소는 11~46%, 불소는 69~99%을 보였다. 결론적으로 RO는 질산성질소와 불소의 높은 제거율이 가능하나 에너지 비용이 부담된다. EC는 질산성질소와 불소의 효과적인 제거가 가능하나 슬러지 발생 부담이 있다. 반면 MWCNT를 활용한 EA는 전극 제조방법에 따라 제거율에 큰 차이를 보였으며 전극의 지속적 사용을 위한 안전성 확보가 시급한 개선점으로 나타났다. Comparison of removal performance between reverse osmosis(RO), nanofiltration(NF), electrocoagulation(EC) and electroadsorption(EA) for removal of nitrate and fluoride often exceeded the limits of water quality in small water treatment plants. Removals of nitrate and fluoride were 72-92% and 74-85% in RO, 5-15% and 1% in NF, 99% and 44% in EA equipped with MWCNT coated electrodes, 82% and 77% in EA equipped with Cu-MWCNT electrodes, and 11-46% and 69-99% in EC. Consequently, high removals of both ions were anticipated in RO. Effective removal of both ions are possible for EC, but great production of sludge is a big burden. EA equipped with the MWCNT electrodes showed a great fluctuation in removal efficiency, and electrode stability should be upgraded.

ASSESSMENT OF POSSIBILITY OF AGRICULTURAL USE OF MUNICIPAL SEWAGE SLUDGE GENERATED IN SELECTED SMALL SEWAGE TREATMENT PLANTS FROM KRAKÓW DISTRICT

The paper presents the findings from research on physical chemical parameters as well as on microbiological-parasitological municipal sewage sludge from one mediumsized and three small municipal sewage treatment plants from the area of Krakow district. The research was conducted in the years 2007-2012 and aimed at estimating the possibility of agricultural use of the studied sludge. The analyzed sludge turned out to be rich in fertilizing elements, i.e. organic substance, nitrogen, phosphorus, calcium and magnesium. Contents of heavy metals in the analyzed sludge were distinctly lower than the permissible contents in sludge used in agriculture. However, due to frequent occurrence of bacteria from Salmonella group in the studied sludge, its agricultural use may be limited. Relatively high variability in the determined parameters makes it necessary to monitor continuously the sludge coming from particular lots and sewage treatment plants.

Typology of Municipal Wastewater Treatment Technologies in Latin America

AbstractThis paper presents an analysis of the wastewater treatment plants in six Latin American and Caribbean countries. Based on a sample of 2734 municipal treatment facilities, the applied processes are classified by sizes (influent flow) and type of technologies. The distribution of the technologies is also presented for each of the six countries. In addition, a representative municipal wastewater characterization, based on influent data from 174 treatment plants, is proposed. Results show that stabilization ponds, activated sludge, and the upflow anaerobic sludge blanket reactors represent 80% of the treatment facilities of the sample, providing treatment to 81% of the total flow considered. Moreover, 67% of the plants in the sample are small (flow <25 L/s) and the very small facilities (influent flow <5 L/s) are extensively applied in the region (34% of the sample), especially in Mexico and Brazil. The use of very small treatment plants may result in low energy efficiency systems and on possible incompliance of the discharge standards. This common practice in several countries in Latin America should be revised in order to improve the environmental performance of such facilities.

Depletion of Cryptosporidium parvum Oocysts from Contaminated Sewage by Using Freshwater Benthic Pearl Clams (Hyriopsis schlegeli)

The freshwater benthic pearl clam, Hyriopsis schlegeli, was experimentally exposed to Cryptosporidium parvum oocysts, and it was verified that the oocysts were eliminated predominantly via the fecal route, retaining their ability to infect cultured cells (HCT-8). The total fecal oocyst elimination rate was more than 90% within 5 days after exposure to the oocysts. H. schlegeli was able to survive in the final settling pond of a sewage plant for long periods, as confirmed by its pearl production. In the light of these findings, the clam was placed in the final settling pond in a trial to test its long-term efficacy in depleting oocysts contaminating the pond water. The number of clams placed was set to ensure a theoretical oocyst removal rate of around 50%, and the turbidity and the density of feed microbes in the overflow trough water of the pond were about 35% and 40 to 60% lower, respectively, than in the control water throughout the year. It was found that the clam feces containing oocysts were sufficiently heavy for them to settle to the bottom of the pond, despite the upward water flow. From these results, we concluded that efficient depletion of oocysts in the sewage water of small or midscale sewage treatment plants can be achieved by appropriate placement of H. schlegeli clams.

HEAT BALANCE COMPONENTS OF A SMALL SEQUENCING BATCH REACTOR APPLIED FOR MUNICIPAL WASTEWATER TREATMENT

In Romania, over 40 % of the population lives in rural areas where wastewater infrastructures are poor or missing. Development of infrastructure in water supply and sewerage is essential for improving living conditions and human health. To solve the problem of domestic wastewater treatment in the areas where only decentralized sewage treatment systems can be implemented, compact installation that operating as a Sequencing Batch Reactor (SBR) process can be used. Unlike the conventional biological mechanical wastewater treatment systems, in which the process is divided into several basins, the treatment system that uses the SBR process segregates the treatment process by working times. Therefore, the compact installation that uses SBR process is among the most effective alternatives to the conventional wastewater treatment with low flow. To ensure a high degree of treatment in small treatment plants which operates by SBR process, it is essential to identify the correlations among some parameters, such as: qualitative and quantitative characteristics of the influent, construction characteristics of the treatment system and operating factors. The main direction of this research aims at identifying the mathematical model able to describe the heat balance for a SBR used in a small municipal wastewater treatment plant. Moreover, the theoretical model was correlated with the numerical values obtained during 30 days of measurements and monitoring of a small wastewater treatment plant used to treat real municipal wastewater. The installation used in this research was used in real condition to obtain the values as close to reality for the component of the heat balance.

Wastewater disposal in rural areas

Abstract In rural areas, the quality of the water bodies will continue to be influenced by the purification performances of small and smaller wastewater treatment plants (WWTPs). In this paper, the different methods of wastewater discharge and treatment currently available for rural areas were presented. Today, both technical and natural methods achieve purification results which are equivalent to, if less stable than those of larger technical pants, provided that dimensioning, design, and operation are optimally cared for. The general question will be to decide for a centralized wastewater system or for local, on-site solution installing small treatment plants. Important criteria for this decision as the distance between the houses and also crucial dimensioning parameters like the amount of wastewater will be given within the report. Several wastewater treatment technologies will be explained and also results from the SBR-System, which are applied in Germany special in smaller communities, are discussed....

Artificial neural network modeling for predict performance of pressure filters in a water treatment plant

Abstract Pressure filters are popular in small municipal water treatment plants. One of the principles for designing and using the various units of water treatment plants is the ability of assigning and predicting the performance of those units under different and various conditions that could be verified by making pilot scale tests and could be modeled by means of available programs and software such as artificial neural network. The goals of this study that was conducted to predict pressure filter efficiency are: (1) evaluations of pressure filter efficiency for turbidity removal under different conditions such as turbidity of raw water, filtration rate and filter pressure changes; (2) statistical analysis of results and determination of the minimum and maximum and maximum effluent turbidity from filter; (3) application of Artificial Neural Network as a suitable model of filter efficiency for turbidity removal; and (4) determination of considered model index for the prediction of similar filters efficiencies. For approaching those goals, pilot designation, sampling and analysis were done for 1,300 samples, and the maximum and the minimum effluent turbidity from filter were determined based on statistical analyses. Different structure of Artificial Neural Network were evaluated based on results, and the best structure was selected and its indexes was proposed for future studies; for example the best value for different network schemes like momentum coefficient and training rate were 0.5 and 0.2, respectively.

Performance of small water treatment plants: The case study of Mutshedzi Water Treatment Plant

The performance of small water treatment plants (SWTPs) was evaluated using Mutshedzi WTP as a case study. The majority of SWTPs in South Africa (SA) that supply water to rural villages face problems of cost recovery, water wastages, limited size and semi-skilled labour. The raw and final water quality analyses and their compliance were used to assess the performance of the Mutshedzi WTP. Electrical conductivity (EC), pН and turbidity were measured in the field using a portable multimeter and a turbidity meter respectively. Atomic Absorption Spectrometry and Ion Chromatography were used to analyse metals and non-metals respectively. The results were compared with the Department of Water Affairs (DWA) guidelines for domestic use. The turbidity levels partially exceeded the recommended guidelines for domestic water use of 1NTU. The concentrations of chemical parameters in final water were within the DWA guidelines for domestic water use except for fluoride, which exceeded the maximum allowable guideline of 1.5mg/L in August 2009. Mutshedzi WTP had computed compliance for raw and final water analyses ranging from 79% to 93% and 86% to 93% throughout the sampling period, respectively. The results from earlier studies showed that the microbiological quality of final water in Mutshedzi WTP complied with the recommended guidelines, eliminating the slight chance of adverse aesthetic effects and infectious disease transmission associated with the turbidity values between 1 and 5NTU. The study concluded that Mutshedzi WTP, though moving towards compliance, is still not producing adequate quality of water. Other studies also indicated that the quantity of water produced from Mutshedzi WTP was inadequate. The findings of the study indicate that lack of monitoring of quantity of water supplied to each village, dosage of treatment chemicals, the treatment capacity of the WTP and monitoring the quality of water treated are some of the factors that limit the performance of Mutshedzi WTP. These have been confirmed in literature to be widespread in similar WTPs in SA. It is recommended that water meters be provided and the community be advised to subsidise the cost of water supply. The study recommended that the treatments of turbidity and fluoride should form critical functions of the plant to ensure that final water for domestic use is always safe from any harmful substances or disease causing pathogens. The study concluded that the WTP only needs minor improvement to boost its efficiency with regard to the treatment of raw water. This will also ensure that the plant achieves 100% compliance for final water.

Determination of atrazine in surface waters by combination of POCIS passive sampling and ELISA detection

Polar organic compound integrative samplers (POCIS) in combination with instrumental techniques such as LC-MS-MS were previously used to monitor environmental pollutants but the performance of alternative immunochemical methods such as ELISA (enzyme-linked immunosorbent assay) has been explored less. In the present study, POCIS technology was applied to surface water sampling in the Czech Republic, and ELISA was used as a detection technique for the herbicide atrazine. In the first study, 28 samples from streams around small municipal waste water treatment plants (WWTPs) were collected using two different devices (POCISpest and POCISpharm) over the course of 21 days. Elevated atrazine concentrations (up to 25 ng per POCIS) were found in samples down-stream of WWTPs. This observation was also confirmed in another two year study (4 sampling periods) investigating 7 river sites around a major city of Brno as well as the inlet and outlet of the city's WWTP. High atrazine levels were systematically determined at the outlet from the WWTPs (120-605 ng per POCIS). A decreasing trend in the atrazine concentrations in rivers around the city of Brno has been observed, with the highest levels observed within the first sampling period in spring 2007 (100-600 ng per POCIS, with an extreme value of 2760 ng per POCIS). Results of the atrazine ELISA were closely correlated with LC-MS/MS, which confirmed good applicability of ELISA as a cost-effective screening tool.