Rainwater Treatment Research Articles

Flocculation-Magnetic Separation Technology for the Rapid Treatment of First Flush Rain

In order to rapid treatment of first flush rainwater, a new flocculation-magnetic microsphere was prepared. And magnetic microspheres were prepared using the modified Stöber method. Magnetite (Fe3O4)-silica (SiO2) core-shell microspheres have superparamagnetism verified by using XRD, FTIR and VSM analysis. Also, Fe3O4/SiO2 (FS) microspheres have no significant reduction after at least reused five times. The optimal feeding order and conditions were flocculant, magnetic powder and PAM, reaction temperature 25 °C, static sedimentation time 30 min, and pH=7. Under the optimized condition, 62% of COD and 98% of turbidity were removed. Especially, Fe3O4/SiO2 microspheres can effectively adsorb heavy metal ion.

Capture, treatment and reuse of gray and rainwater in single-family residence

The objective of this work is to present a bibliographic review, the subject of which is the reuse of water by rain, as well as the reuse of gray waters in a single-family residence. For this, the methodology constitutes a search for information in books, magazines, articles, master’s dissertations and doctoral theses. To consciously reuse, ways to capture water from a residence, whether from the rain that falls on the gutters or used in the methods of capture in the kitchen sinks and/or tanks of service areas that will receive the necessary treatment and will be reused. These treatments act efficiently and provide the use of this water for less noble purposes which makes consumption more rational and economical, cooperating for the maintenance of environmental resources. Keywords: Water, reuse, capture, treatment, residence.

Discussion on Integrated Design of Emergency Storage Facilities for Dangerous Chemicals Transportation Accidents and Bridge Drainage Run off Treatment Facilities of Expressway

Based on the investigation on the collection and treatment of the runoff from the bridge-deck of some expressways involving sensitive water bodies, this paper proposed an integrated design idea of the emergency storage facility and the bridge-deck rainwater runoff treatment facility for the transportation accident of dangerous chemicals in the expressway. The integrated design idea improves the disadvantages of simultaneous treatment of rainwater and accident-water in the bridge-deck runoff treatment system. The process flow, plane layout, functional unit volume design, conversion device, and control system involved in the integrated design are discussed.

Controlling Disinfection By-Products Formation in Rainwater: Technologies and Trends

With an augmenting lack of pure water, rainwater has been viewed as an invaluable substitutional potable water fountain. The methods implemented for rainwater treatment are in control of the safety of potable water. Researchers examined various disinfection methods to estimate the monitoring of disinfection by-products (DBPs) generation. The tried disinfection techniques involved chlorination and chloramination, pre-oxidation by potassium permanganate (KMnO4) and potassium ferrate (K2FeO4), ultraviolet/hydrogen peroxide (UV/H2O2), and ultraviolet/persulfate (UV/PS) methods. In spite of low contaminants existing in rainwater comparatively with surface water, the same findings are mostly obtained in terms of DBPs production and control procedures using the above-mentioned technologies. Employing granular activated carbon post-treatment could greatly reduce the concentrations and poisonous effects of DBPs. Moreover, secure multi-barrier techniques, like distillation and membrane processes, remain to be suggested, tested and industrially encouraged.

Comparison of different disinfection processes for controlling disinfection by-product formation in rainwater

With increasing shortage of clean water, rainwater has been considered as a precious alternative drinking water source. The processes applied to rainwater treatment are responsible for the safety of drinking water. Therefore, we systematically compared different disinfection processes to evaluate the control of disinfection by-product (DBP) formation and integrated cyto- and genotoxicity of the treated rainwater for the first time. The evaluated disinfection processes included chlorination and chloramination, pre-oxidation by potassium permanganate (KMnO4) and potassium ferrate (K2FeO4), ultraviolet/hydrogen peroxide (UV/H2O2), and ultraviolet/persulfate (UV/PS) processes. The results revealed that chloramination was effective for controlling the formation of carbonaceous DBPs (C-DBPs), but not nitrogenous DBPs (N-DBPs). Compared to KMnO4 pre-oxidation, better reduction of almost all DBPs was observed during K2FeO4 pre-oxidation. According to the calculation of cytotoxicity index (CTI) and genotoxicity index (GTI), cyto- and genotoxicity of the samples decreased obviously at the dosage of ≥ 2.0 mg/L KMnO4 and K2FeO4. The control of the cyto- and genotoxicity of the formed DBPs from the two UV-related AOPs was more effective at the dosage of ≥ 1.0 mM PS and ≥ 5.0 mM H2O2. Moreover, UV/PS was much more powerful to alter the structure of DBP precursors in rainwater.

Predatory bacteria in combination with solar disinfection and solar photocatalysis for the treatment of rainwater

The predatory bacterium, Bdellovibrio bacteriovorus, was applied as a biological pre-treatment to solar disinfection and solar photocatalytic disinfection for rainwater treatment. The photocatalyst used was immobilised titanium-dioxide reduced graphene oxide. The pre-treatment followed by solar photocatalysis for 120 min under natural sunlight reduced the viable counts of Klebsiella pneumoniae from 2.00 × 109 colony forming units (CFU)/mL to below the detection limit (BDL) (<1 CFU/100 μL). Correspondingly, ethidium monoazide bromide quantitative PCR analysis indicated a high total log reduction in K. pneumoniae gene copies (GC)/mL (5.85 logs after solar photocatalysis for 240 min). In contrast, solar disinfection and solar photocatalysis without the biological pre-treatment were more effective for Enterococcus faecium disinfection as the viable counts of E. faecium were reduced by 8.00 logs (from 1.00 × 108 CFU/mL to BDL) and the gene copies were reduced by ∼3.39 logs (from 2.09 × 106 GC/mL to ∼9.00 × 102 GC/mL) after 240 min of treatment. Predatory bacteria can be applied as a pre-treatment to solar disinfection and solar photocatalytic treatment to enhance the removal efficiency of Gram-negative bacteria, which is crucial for the development of a targeted water treatment approach.

Effects of Continuous Extreme Rainfall on Water Quality of the Dongjiang River Basin

In order to research the impact of continuous extreme rainfall on the water quality of the Dongjiang River, which is a drinking water source, the characteristics of extreme rainfall events in the basin were analyzed for last 38 years. The impacts of these events on water quality are discussed by considering both hydrological data and water quality data. Using SWAT2012 software, a high-precision basin model was established for the flux of major pollutants during extreme rainfall and water quality. The results indicate that there were 173 extreme rainfall events in the Dongjiang River basin over the past 38 years. The annual frequency of extreme rainfall events in high-flow years was higher than in other years. During the year, rainfall was mainly affected by climate, particularly from March to September (80%), with the peak rainfall usually occurring in June. Spatially, the Zengcheng-Bolo-Huizhou-Longmen area had the highest frequency of extreme events. During the study period, rainfall was significantly positively correlated with the concentrations of cyanide, Pb, Fe, Mn, TP, and with turbidity, and the correlation coefficients for the concentrations of TP and turbidity with rainfall were relatively high. Rainfall was significantly negatively correlated with pH, conductivity, the concentration of Zn, as well as some other indicators. These observations show that water quality is affected by rainfall to some extent. Turbidity, TN, ammonia nitrogen, and TP concentrations all showed increasing trends, to different degrees, during rainstorm runoff periods. Turbidity and TP concentrations showed a significant and consistent relationship with flow rate, peaking earlier than the flow rate peak (by approximately 1 d), showing a significant initial flushing effect. The pH curve showed an opposite trend to the flow rate, forming a "V" shape, which may be affected by the rainfall, soil acidity, and confluence conditions in the upstream mountains. Ammonia nitrogen was subject to initial flushing in the early stages of extreme rainfall but was diluted by the clean rainwater; initially, ammonia nitrogen showed high values that declined during the middle and late stages. The variations in pollutant loads were consistent with that of runoff flux, and the peaks in TN, ammonia nitrogen, and TP flux appeared later than the flow peak (by approximately 1 d), thus differing from the pollutant concentration peak. The pollutant load mainly showed a significant increase during storm runoff periods. The proportion of pollutant COD, ammonia nitrogen, and TP transported by 59.48% of the runoff reached 68.42%, 54.68%, and 70.20%, respectively, demonstrating the characteristics of rapid and high-impact pollutant loads. These characteristics have a great influence on the quality of Dongjiang River drinking water and it is suggested that initial rainwater treatment should be strengthened to reduce the negative impact of rainstorm runoff periods on water quality.

Efficient Storm Water Management and Rainwater Harvesting System: a Case Study in Swami Vivekananda Airport Raipur

Water is crucial and it has always been considered throughout history as a natural resource for the survival of humanity and other living beings therefore globally the shortage of quality water and its availability is an important issue. Groundwater is the only source of water of the Swami Vivekananda Airport Raipur, and it faces water crisis when the groundwater level decreases. In this scenario, Rain Water Harvesting (RWH) can contribute considerably to tackle these problems. Rainwater treatment systems can be installed at different potential locations in study area based on their physical site conditions such as slope, elevation etc. The airport has 38955.62 Square meters rooftop area out of 2.108 Square Kilometres total area, water collected from the rooftop will fulfil approximately 30% of the total daily demand of the airport. Apart from this airport is properly designed drainage system storm water is collected and separated into three potential zones. Zone I, II and III having area 0.2393, 0.4307 and 1.4382 sq. Kms respectively, which produce a different runoff amount based on maximum daily rainfall. Storm water is treated by Slow Sand Filter (SSF) of rate of 200 litres per hour per square meter and stored under design capacity, size and number of treatment unit depend on the maximum discharge at their respective zones. Treated rainwater is utilized for recharge purpose through the recharge trench when excess water comes from the rainwater tank. The cost-benefit analysis also done for before and after implementation of the project.

Wetland Roofs as an Attractive Option for Decentralized Water Management and Air Conditioning Enhancement in Growing Cities—A Review

While constructed wetlands have become established for the decentralized treatment of wastewater and rainwater, wetland roofs have only been built in isolated cases up to now. The historical development of wetland roofs is described here on the basis of a survey of literature and patents, and the increasing interest in this ecotechnology around the world is presented. In particular, this article describes the potential for using wetland roofs and examines experience with applications in decentralized water management in urban environments and for climate regulation in buildings. Wetland roofs are suitable as a green-blue technology for the future—particularly in cities with an acute shortage of unoccupied ground-level sites—for the decentralized treatment of wastewater streams of various origins. Positive “side effects” such as nearly complete stormwater retention and the improvement of climates in buildings and their surroundings, coupled with an increase in biodiversity, make wetland roofs an ideal multi-functional technology for urban areas.

Feasibility study of rainwater conservation and harvesting for industrial community in North Jakarta

Rainwater harvesting has been adopted in many regions of the world when raw water supplies are insufficient for the community. A multinational company engaged in heavy equipment around North Jakarta has a rainwater pool facility that can be used to anticipate flooding during the rainy season using the Ground Catchment System method. In addition, this water source can be used to meet the company’s clean water needs both for industrial and domestic needs and to reduce the use of municipal supply water (Perusahaan Daerah Air Minum, PDAM). This study aims to meet the needs of clean water, anticipate floods and droughts. This research uses a problem-solving approach to reduce the use of water from PDAM. The variables studied in this research are average water quantity, water quality, and reduction of water consumption from PDAM by replacing it with clean water from rainwater, and then assess them using qualitative and quantitative method for six months. The results concluded that the quantity of water from rainwater treatment produced during six months of research can reduce the consumption of PDAM water as much as 20%. In general, the rainwater harvesting for the needs of the industrial community in the company can be considered as a feasible solution to provide clean water substitute and to reduce PDAM water consumption.

Rainwater as a Source of Drinking Water: Health Impacts and Rainwater Treatment.

Rainwater is the main source of drinking water in tropical communities, especially in West Kalimantan. Air contamination causes rainwater to become acidic and cloudy and adds heavy metals such as Pb into rainwater. In addition to pollution, the way in which the rainwater is collected such as through zinc roofing also exposes the rainwater to heavy metals. The presence of Pb in rainwater will have an impact on the health of the community in the long run. The model of simple water treatment using filtration is needed to overcome this problem with the use of media available in the region. The media used are in the form of mollusk sand and activated carbon. In the end, the mollusk sand filtration model and activated carbon sorption were effectively used to filter polluted rainwater to be safe for consumption.

Design for Harvesting and Treatment of Rainwater in Naval, Biliran

Design for Harvesting and Treatment of Rainwater in Naval, Biliran

Comparative Analysis of Granular and Membrane Filters for Rainwater Treatment

The objective of this study was to compare the efficiency of rainwater treatment using two types of filters: one with filtration materials (gravel, sand, and anthracite) and the other employing membranes. In both cases, the quality of the rainwater after passing through the filter met the standards required by NBR 15527:2007 (Brazilian Association of Technical Standards (ABNT)) and the United States Environmental Protection Agency (EPA) for non-potable uses according to the parameters pH, temperature, turbidity, ammonia, nitrate, nitrite, alkalinity, and calcium hardness. The results obtained were also compared with Directive 2914/2011 of the Brazilian Ministry of Health, which deals with water potability, and with Resolution 357/2005 of CONAMA (Brazilian National Council for the Environment), which is applied to surface water bodies, especially rivers, and establishes the possibility of direct contact of the water with human skin. It was concluded that the rainwater obtained from both filters could be used for non-potable uses, such as toilet flushing, garden irrigation, and sidewalk cleaning, as well as for direct-contact activities, such as bathing and washing clothes.

San Blas: Del ocaso al renacimiento. Paradigma temprano de gestión del patrimonio en el sur peruano. El caso del barrio histórico de San Blas en la gestión municipal del Cusco 1990-1993

La presente investigación analiza la política de gestión aplicada en las intervenciones realizadas en el Barrio Histórico de San Blas, emplazado en el Centro Histórico de Cusco, durante el periodo 1990-1993, gestión municipal del burgomaestre, abogado y político Daniel Estrada Pérez “Qosqoruna”. Dichas intervenciones, reunidas en el documento Obras de Remodelación Integral de antiguo Barrio de THOQO KACHI (San Blas), comprendieron “trabajos de pavimentación de sus pintorescas calles, iluminación moderna, tratamiento de fachadas y aguas pluviales” (Municipalidad del Qosqo, Mi Nuevo San Blas, 1993 p. 10), el tratamiento de la plaza y la inserción de paqchas(*), hecho que generó la apropiación e identificación del vecino sanblaseño con el espacio público, devenir del impacto sociocultural y económico positivo generado a raíz de la intervención en su traza urbana patrimonial.&#x0D; (*) "Piletas" en quechua.

Assessment of runoff treatment operations with combined rainwater treatment system in the old city zone

Abstract Considering the diversity of pollution degree in different underlying surfaces, and the great difficulty in construction and high economic cost for an existing built community in an older city zone, in order to rationally distribute the load carrying capacity of each treatment facility, a design concept of combined rainwater treatment system was put forward to treat vehicle lane rainwater, square rainwater, and roof rainwater. In this study, one older city zone in Guangming new district, north-western Shenzhen, China was selected to meet the combined treatment of vehicle lane rainwater and roof rainwater, and four typical rainfall events were selected to analyze the water quantity and water quality control effect of this combined rainwater treatment system under different rainfall intensity and rainfall duration. Results showed that under the treatment of initial treatment facility and biological filtration facility, the runoff volume of vehicle lane and roof were all controlled effectively, and the discharge amount of different pollutants was also reduced effectively although initial treatment facility and biological filtration facility could not effectively decrease pollutant concentration. Therefore, this combined treatment of vehicle lane rainwater and roof rainwater can provide reference for the popularization and application of different kinds of combined rainwater treatment systems.

Economic analysis and risk-based assessment of the financial losses of domestic rainwater harvesting systems

The considerable potential for rainwater harvesting (RWH) opens the door for the study of economic viability and risk indicators in this kind of system. The aim of this paper was to present economic and risk analyses of three RWH systems intended for water supply to single-family residences. The systems were analyzed based on water demand, degree of treatment and distribution arrangement. Economic, sensitivity and risk analyses were performed. The system with the basic treatment of rainwater and distribution by pressure (BX Pressure) was the most economically viable. The Net Present Value and the Intern Return Rate of the BX Pressure system was 480.36 USD and 6.85%, respectively. In the sensitivity analysis, both basic treatment systems were viable at any considered discount rate (0.00%–10.00%) and at a water price ranging from 1.58 USD to 2.72 USD for BX Pressure. In the risk analysis, BX Pressure was also the most viable system, presenting a risk probability of viability of 95.9% at current water prices. Water price, demand, lower discount rates and initial investment costs determined the greater economic viability and lower economic risk associated with domestic RWH systems.

The filtering efficiency of iron and salt of city rainwater by sand filtration process

The aim about the study was to improve the filtering efficiency of sand filter in the treatment of urban rainwater in residential area. In the experiment, a better sand filter was designed through changing the filtering materials and measuring the filtering efficiency for the urban rainwater treatment. Because of the weather conditions, not enough rainwater could be collected so that the stimulated rainwater which contained the same concentration of measured pollutants was used in the process of sand filtration. The experiment was divided into two parts, one part was the efficiency of salt removal and another was the efficiency of iron removal. In the salt removal testing, four sand filters were filled with different filtering materials which included 40 cm sand, 30 cm sand with 10 cm activated carbon, 30 cm sand with 10 cm zeolite, and 30 cm sand with 10 cm limestone, through pumping into a certain concentration of salt solutions and then getting the filtering efficiency of the sand filter. The second part of experiment was about iron testing. The iron testing included no salt iron testing which set three different concentration of iron (3 mg/L, 6 mg/L, 9 mg/L) and iron mixed with salt testing. (3 mg/L iron with 200 mg/L concentration or 400 mg/L concentration of salt, 9 mg/L of iron with 200 mg/L concentration or 400 mg/L concentration of salt). Then pumping into four sand filters filled with the same material like salt removal testing and get the efficiency of sand filter. The best filtering material and sand filter improvement would be determined through the two parts of the experiment and compared the filtering efficiency. Through the testing, the filtering material was strength the filter capacity. Otherwise, the zeolite had the best filtering efficiency in the salt testing and the following was limestone, activated carbon and sand. The iron testing was failed because the long stored of the filtering solutions.

The Reference of Australian Water Sensitive Urban Design Practice to Sponge Cities in China

Water Sensitive Urban Design（WSUD）is a spatial design method which integrates urban design and urban hydrological management. Under the current background of sponge city construction, it promotes the collection, treatment and recycling of rainwater by optimizing the urban material space form, reducing the impact of urban development on natural water circulation system. Water-sensitive urban design was introduced in Australia earlier, and remarkable results have been achieved in design methods and planning practice. Taking WSUD in Australia as an example, this paper elaborates the urban design strategy based on water sensitivity, and draws lessons from Australia's experience in integrating water sensitivity design into practical design and construction at various levels, such as policy, concept, space and technology, in order to provide useful ideas for the construction and development of sponge cities in China and related research in the field of urban design.

Recycling rainwater by submerged gravity-driven membrane (GDM) reactors: Effect of hydraulic retention time and periodic backwash

Rainwater recycling has been considered as an alternative cost-effective decentralized water supply. The low cost and effective gravity-driven membrane (GDM) filtration technology has been introduced to treat the rainwater prior use. In this study, we investigated the effects of hydraulic retention time (HRT; 27 h, 51 h, and 156 h) and periodic backwash durations (2 min, 5 min, 10 min, and 30 min per 2–3 days' filtration) on the permeate quality, flux and fouling mechanism in lab-scale submerged GDM reactors. Compared to the performance at HRT of 51 h (40% of DOC removal and ~2.9 L/m2 h), better permeate quality and higher membrane flux were achieved at HRT of 27 h (51% of DOC removal and ~4.2 L/m2 h) and 156 h (48% of DOC removal and ~5.0 L/m2 h). Although the hydraulically reversible resistance was predominant (up to 90% of the total fouling resistance), the permeate flux could not be fully recovered by periodic backwash, regardless of the backwash durations. After several filtration-backwash cycles, the stabilized flux of GDM reactor with backwash was even worse than those without backwash. However, no correlation can be established between the stabilized flux (i.e., cake layer resistance) and the soluble organics and microbial cells in the cake layer of the GDM system during rainwater treatment.

Water Circulation Construction exploration of Sponge City in Weidong-new-city

The sponge city has been transformed from theory into a rainwater harvesting and utilization project being implemented in many cities in our country. Rainfall control and utilization are no longer on the bargain but as an important strategy for the state to guide urban construction. In order to achieve the purpose of controlling rainwater resources and the utilization of rainwater resources, combining rainwater treatment with landscape design is the most direct and effective method. At the same time, the urban water also includes the urban landscape water. If the landscape can solve the problem of rainwater control and rainwater utilization by its own advantages, it not only makes full use of the rainwater resources but also saves the urban water resources. Based on the experience of foreign countries and the reference of the case, we also need to carry out a systematic study of its specific contents. The purpose of this paper is to systematically study the concept of sponge city under the premise of low impact on the development concept, The type of urban greenland related to landscape is analyzed in depth, the role of different types of sponge facilities in stormwater management is summarized, and the concept, construction and related issues of sponge city are briefly analyzed.