Initial Rainwater Research Articles

Small-Intensity Rainfall Triggers Greater Contamination of Rubber-Derived Chemicals in Road Stormwater Runoff from Various Functional Areas in Megalopolis Cities.

Rubber-derived chemicals (RDCs) originating from tire and road wear particles are transported into road stormwater runoff, potentially threatening organisms in receiving watersheds. However, there is a lack of knowledge on time variation of novel RDCs in runoff, limiting initial rainwater treatment and subsequent rainwater resource utilization. In this study, we investigated the levels and time-concentration profiles of 35 target RDCs in road stormwater runoff from eight functional areas in the Greater Bay Area, South China. The results showed that the total concentrations of RDCs were the highest on the expressway compared with other seven functional areas. N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), 6PPD-quinone, benzothiazole, and 1,3-diphenylguanidine were the top four highlighted RDCs (ND-228840 ng/L). Seasonal and spatial differences revealed higher RDC concentrations in the dry season as well as in less-developed regions. A lag effect of reaching RDC peak concentrations in road stormwater runoff was revealed, with a lag time of 10-90 min on expressways. Small-intensity rainfall triggers greater contamination of rubber-derived chemicals in road stormwater runoff. Environmental risk assessment indicated that 35% of the RDCs posed a high risk, especially PPD-quinones (risk quotient up to 2663). Our findings contribute to a better understanding of managing road stormwater runoff for RDC pollution.

Operational effect of green roof systems with a modified substrate adding soda residue soil

ABSTRACT To investigate whether soda residue soil could be used as a green roof substrate, this paper setup six green roof systems with four materials (peat soil, coconut bran, perlite, and soda residue soil) mixed in different volume proportions. The effect of soda residue soil content on Sedum lineare growth and pollutant removal from the stormwater runoff was analyzed and the runoff quality index (RQI) was calculated. Results showed that the relative growth rate of S. lineare height in system B with 10% soda residue soil was about 21.5–53.2% higher than the other systems. The outflow of system B with 10% soda residue soil had the lowest mass concentration of NH4+-N and TN, which were 2.2 and 3.2 mg/L, respectively. The average repetitive rainfall retention rate of system A without soda residue soil was the lowest at 82.6%. System B had the highest RQI at about 0.71. It confirmed that soda residue soil can be a material with practical application value, and when the volume ratio of peat soil, coconut bran, perlite, and soda residue soil was 4:3:2:1, the green roof would have the best performance in regulating and purifying the initial rainwater runoff.

The Application of an Electrocoagulation Process to the Sustainable Treatment of Initial Rainwater and the Simulation of a Flow Pattern in an Experimental Device

The pollutant content in initial rainwater is very high, so the treatment and research of initial rainwater has become an engagement issue in controlling non-point source pollution and realizing sustainable development in Chinese cities. This study explores the best flow pattern suitable for treating initial rainwater by electrocoagulation (EC), and a pilot-scale experiment is conducted to analyze the effect of the EC process on the treatment of initial rainwater. The findings indicate that the latter enhances the turbulent flow effect and the EC process treatment effect better under the two flow modes of parallel perforation flow and dislocation perforation flow. For the dislocation perforated flow pattern, the removal rates of suspended matter (SS), chemical oxygen demand (COD), and phosphorus (TP) are 94.00%, 81.95%, and 98.97%, respectively, which reach the expected treatment targets. Using the electrocoagulation–filtration (ECF) process to treat initial rainwater, the final effluent exhibits high quality and could be used as urban circulating cooling water. Specifically, SS, COD, and TP concentrations are 15.00 mg/L, 21.06 mg/L, and 0.11 mg/L, respectively. The hydraulic retention time of the process is short, only 30 min, and the energy consumption is low, 0.57 kWh. This study provides a reference for the sustainable treatment of early urban rainwater and the design of the flow pattern of the EC process.

Water quality improvement project for initial rainwater pollution and its performance evaluation

Efficiently addressing initial rainwater pollution is crucial for mitigating urban water pollution. However, the performance evaluation of initial rainwater pollution control project is rarely introduced. In this study, the architecture of effective comprehensive engineering measures for improving the water quality of initial rainwater in Anhui Province, China, was described. Three water quality indicators, ammonia nitrogen (NH3–N), chemical oxygen demand (COD), and total phosphorus (TP), were selected to explore the severity of urban pollution caused by initial rainwater under various rainfall scenarios. A single-factor evaluation method was used to contrast and assess the benefits of the initial rainfall interception project in terms of water quality enhancement. Results showed that initial rainfall pollution was gentler under light rainfall conditions but more prominent under moderate and heavy conditions. The percentages of NH3–N, COD, and TP in Lotus Pond that met the tertiary drinking water standard were 100%, 74.91%, and 100% with great improvement, and the average concentrations of NH3–N, COD, and TP in Fushan Road Drainage have decreased by 91.43%, 10.49%, and 57.33% respectively, after the construction of the interception project. These indicated that the nitrogen and phosphorus pollution were successfully controlled by the control techniques in both locations, but COD concentration has to be addressed with more specialized strategies. Overall, the water quality improvement project for initial rainwater pollution plays a great role in effectively governing initial rainwater pollution and improving river water quality, and provides an effective technical reference for urban water ecological environment management.

Evaluation of the comprehensive efficiency of the interception pipeline in the urban rainwater pipe network for the initial rainwater collection and storage

Urban runoff pollution has become one of the important limiting factors hindering the continuous improvement of water environment. In the process of drainage system reconstruction, the evaluation of interception pipeline for the collection and storage efficiency of initial rainwater is an important work. Therefore, this study uses the analytic hierarchy process to establish an evaluation system and method containing 4 first-level indicators and 10 second-level indicators to evaluate the comprehensive efficiency of the interception pipeline for initial rainwater collection and storage. Taking the interception pipeline in a drainage system in Shanghai as a case study, the established evaluation method was adopted to evaluate it, and the comprehensive indexes under the rainfall return periods of 0.5 year, 1 year, 3 years and 5 years were calculated. The results indicated that the evaluation method could be well applied to the effectiveness evaluation of intercepting pipelines in drainage systems, and could provide technical support for the planning and design of urban runoff pollution control projects in the future.

Physicochemical and Microbiological Quality of Roof-harvested Rainwater in Urban Areas: A Review

This work proposes to consider the quality of roof-collected rainwater. There are three main stages. In the first stage, rainfall washes out the urban atmosphere with contaminants from aerosols and gases. The second stage refers to the catchment, where there is contamination due to the wash-off of particles settled on the roof’s surface roofing materials. The third stage refers to the first-flush, storage and plumbing system. In each stage, different processes take place and add specific contaminants to the initial precipitation. Only in the third stage, after the discard of the high-polluted initial rainwater, some physical processes (for example sedimentation and correction of pH) can also improve the quality of the rainwater harvest. This approach offers a clear view of the overall contamination processes that take place in a rainwater harvesting system.The most common microbiological and physicochemical contaminants that can be found in rainwater harvesting system were considered, together with the eventual presence of waterborne pathogens and emerging chemical contaminants, according to an extensive review of previous scientific works. Keywords: Rainwater, Physicochemical, Microbiological, Contaminants, waterborne DOI: 10.7176/JEES/12-10-05 Publication date: October 31 st 2022

Design Strategy of Emergency Pools at Source Water Protection Areas

The pollution problem arising from the flushing of initial rainwater and wastewater from accidents while transporting dangerous goods to source water protection areas needs to be solved as soon as possible. Therefore, the design of corresponding environmental protection measures should be considered in the engineering design stage. It is necessary to analyze the specific work in combination with engineering examples. Under this background, this paper first briefly expounds the precautions in accident risk analysis and the design of tank capacity and tank body. Finally, by analyzing actual cases, this paper systematically studies the design strategy of emergency pool in source water protection area, hoping to provide new development ideas for the upgrading of relevant work.

High-Performance Capacitive Deionization and Killing Microorganism in Surface-Water by ZIF-9 Derived Carbon Composites.

The protection and regeneration of the water environment is currently one of the most critical concerns for the sustainable development of human society. To solve the water crisis, the use of capacitive deionization (CDI) technology to extract fresh-water that is suitable for human consumption from abundant surface-water is a feasible solution. In this work, a cobalt benzimidazole frameworks (ZIF-9) derived carbon composites with a unique quasi-microcubic morphology is synthesized and used the as-prepared materials as an electrode material for the CDI. Interestingly, the ZIF-9 derived carbon composites exhibit an impressive desalination capacity of 55.4mgg-1 and can be reused. Measurements in surface-water (Beijing-Hangzhou Grand Canal, Slender West Lake, Initial rainwater, Rain water) show that this CDI technology based on ZIF-9 derived carbon composites not only has a strong adsorption effect on metal ions but also can remarkably kill microorganisms. The results show that the technology can effectively kill bacteria (Escherichia coli and Bacillus) and algae with 95% and 91.7% inhibition rates, respectively. This work provides a valuable example for the use of metal-organic framework-derived carbon composites as high-performance electrode materials of CDI and opens a new direction for promoting the application of CDI in surface-water.

The Initial Rain Water Storage Tank Volume Determination and Pollution Interception Efficiency Based on the Swmm Model and Computer Software Analysis

At present, many cities in China have both severe water shortages and waste of large amounts of rainwater resources during heavy rains caused by urbanization. Turning rainwater resources into cities can reduce urban runoff and reduce peak floods. At the same time, it can increase urban water supply, beautify and clean the urban environment, improve urban microclimate, reduce ground subsidence, control rain and flood processes and reduce urban flood control. Drainage infrastructure investment greatly reduces urban flood disasters, which will bring considerable economic, social and environmental benefits. Therefore, as one of the hot topics in the preparation of special plans for drainage engineering in the new period, urban rainwater should be carried out using the SWMM model and computer software. The plan provides the possibility for further compiling special plans for rainwater utilization and guides the utilization of urban rainwater resources.

Simulation of interception capacity of Nanhe initial rain storage tanks

River pollution sources are generally divided into point source, non-point source and internal source, non-point source pollution is mainly urban surface runoff. In this paper, the non-point source pollution model of SWMM in Nanhe region is constructed, and the water quantity and quality are verified by the measured data, and the verification results are in good agreement with the measured data. On this basis, the detention time and the interception amount of initial rain are analyzed. The results show that after intercepting the initial rainwater, the pollutants into the river are significantly reduced, and the lower the frequency is, the better the interception effect of the storage tank on the initial rainwater is. Comprehensive analysis shows that the overall removal rate of pollutants in each frequency of the four outlets of the storage tank can reach 37~39%.

Spectral Characteristics and Sources of Dissolved Organic Matter from Landscape River During Flood Season in Suzhou Based on EEMs and UV-vis

Based on excitation emission matrix spectroscopy (EEMs) technology combined with the parallel factor analysis (PARAFAC) and UV-vis spectra, the spectral characteristics and sources of dissolved organic matter (DOM) from a landscape river were analyzed during different periods of the flood season in Suzou. Four fluorescent components were identified using the PARAFAC model, including two humus-like components (C1, C4) and two protein-like components (C2, C3), with a significant correlation coefficient (P<0.01) in C2 and C3/C4 and C3 and C4, respectively. During the early flood season, the total fluorescence intensity of the DOM in the river was relatively higher due to the influence of initial rainwater but reduced significantly towards the middle and late flood season. The fluorescence characteristic parameters indicated that the autochthonous contribution of DOM were substantial during the early stages of the flood season. On the contrary, there were increased levels of DOM largely from terrestrial origins during the middle flooding period. During the entire flood season, SUVA254, SUVA260, and E2/E3 exhibited the same trend, that is, decreasing first and then increasing. As a result of the continuous heavy rainfall during the flood season, the nitrogen and phosphorus nutrient content in the channel increased. The algae population did not proliferate in large quantities because of the strong hydrodynamic conditions experienced throughout the flood season. The fluorescence components C2, C3, and C4 exhibited a significant correlation coefficient (P<0.01) with the characteristic parameters (FI, HIX, BIX, and β:α). All the fluorescence components had a high correlation (P<0.05) with DOC. There was a considerable correlation between fluorescence component C1 and Chla. The principal component analysis revealed that the DOM components in the landscape river during different periods of the flood season exhibited notable differences, and the continuous heavy rainfall during the flood season has a substantial influence on the content of C2, C3, and C4 components in the water body.

Research On the Change of Rainwater Quality in the Early Stage of River Discharge

The primary rainwater non-point source pollution is one of the main pollution reasons affecting river water quality. Based on the comprehensive analysis of the rainfall data, initial rainwater quality data and catchment area data, this paper obtains the variation rules and pollution characteristics of the initial rainwater quality at different catchment ranges of river outfall, and provides suggestions for the control of primary rainwater non-point source pollution of the target river outfalls. In the target River outlet of this study, the commercial area is the first to reach the peak of COD and ammonia nitrogen in the initial rainwater quality, and the living area is the highest in the initial rainwater COD and ammonia nitrogen concentration. Thus the control measures can be taken for the initial rainwater in the commercial area, and the key prevention and control measures can be taken for the higher concentration initial rainwater in the living area.

The application research of rainwater wetland based on the Sponge City

In order to promote the construction of the Sponge City and strengthen the utilization of rainwater resources, this paper attempts to design a wetland that can effectively purify the rainwater. The rainwater quality of Zhengzhou was monitored to provide actual data for follow-up studies. A variety of wetlands with different plants and substrates were constructed to analyze the purification of wetlands on rainwater. The wetland with optimal parameters was selected to ensure the effluent can be reused. The average concentrations of Chemical Oxygen Demand (COD), Total Nitrogen (TN), Nitrate Nitrogen (NO3−-N) and Ammonium Nitrogen(NH3-N) in the initial rainwater were 140.25 mg/L, 13.31 mg/L, 5.77 mg/L and 6.82 mg/L, respectively. The experimental results show that the efficiency of COD purification in each wetland is great, and the differences between wetland are small. Compared with other substrates (gravel, activated carbon, vermiculite), zeolite effectively enhanced the purification effect of wetland on ammonia nitrogen. The purification efficiency of wetland with reed and zeolite is the best, and the removal efficiency of COD, TN, NO3−-N and NH3-N is 86.54%, 89.46%, 95.87% and 80.88%, the nitrogen removal efficiency of this wetland is greatly improved. Based on various reuse standards in china, wetland with reed and zeolite can effectively purify initial rainwater, and the effluent can be used to urban miscellaneous water, landscape water and industrial water. This study has important reference significance and practical value for the construction of rainwater wetland in the process promoting the Sponge City.

Research on the Pollution Characteristics of Pavement Runoff of the Expressway Project in Qiandao Lake District

This research focuses on the Expressway Project of Qiandao Lake District, investigates the meteorological conditions, traffic volume, as well as the relationship between the quality of runoff at drainage facilities and the asphalt concrete pavement and sewage discharge rules through artificial rainwater and natural rainwater, studies and determines the time scale of the initial rainwater flow on the expressway and the spatial scale that needs to be collected and processed.

Evaluation of a Pilot Scale Combined Constructed Wetlands and Stabilization Ponds for Initial Rainwater Treatment

For the storage rainwater quality maintenance and purification and the ecological water replenishment in the rain source river of industrial park, a combined process of “plant stabilization ponds and vertical flow constructed wetlands” was developed. The scale of pilot plant was 20 m3/h. The research showed that the combined process of constructed wetlands and stabilization ponds had a significant removal rate of COD, NH4+-N, TN, TP, SS of 14.13% ∼ 31.99%,33.64% ∼ 77.42%,24.72% ∼ 48.04%,61.29% ∼ 67.20%,45.44% ∼ 76.90%, with better treatment effect on N, P and SS in medium and low concentration. The circulation time has a relatively large impact on the removal rate of COD and SS, and a relatively small impact on NH4+-N, TN, TP, TN and TP.

Nebulization dielectric barrier discharge ionization mass spectrometry: Rapid and sensitive analysis of acenaphthene

A rapid, simple and sensitive method was proposed for low-polar acenaphthene analysis by coupling nebulization with dielectric barrier discharge ionization (N-DBDI). The sample solution was nebulized followed by heating and converted to be gas-phase analyte molecules prior to DBDI. This boosts the collision efficiency of analyte molecules with reactive species and thus the sensitivity, and the high-velocity gas from nebulization guides ions directed to the MS inlet without deflection. The dependence of sensitivity on the operation parameters was systematically investigated. The LOD and LOQ of acenaphthene were determined to be 0.61 ng/L and 2.05 ng/L, respectively, which were superior approximately 30 folds compared to those obtained by other methods. Parameters, including accuracy, precision, reproducibility and utility, were tested to further evaluate the performance of N-DBDI. Real environmental samples, including river water, initial rainwater and mineral water, were analyzed with good accuracy (93.61–103.50%) and satisfactory precision (RSD ≤ 8.92%). These findings suggest that the N-DBDI allows the determination of non/low-polar species at sub-pg/mL possible, and would benefit for the non/low-polar species analysis in real environmental samples.

Optimization Design of a Rain-Power Utilization System Based on a Siphon and Its Application in a High-Rise Building

Rain falling from the sky is viewed as a clean energy source with a great potential, owing to the large amount of it and its zero pollution nature, the fact that it has scattered raindrops, and its characteristic rainfall concentration that promotes extensive research on harvesting and utilization. Here, we introduce a new approach to harvest rainwater on rooftops called the Rain-Power Utilization System, which is composed of an initial rainwater disposal system and multistage energy conversion system. Initial rainwater is discharged into a split-flow pipe due to its poor quality and impurities. Additionally, clean rainwater is accumulated in a storage pipe until the water level reaches a specified height, triggering siphonage for energy conversion. The same process is repeated in other storage pipes connected in series. Function relations among physical and dimension parameters have been established for further studies. A kind of simplified optimization algorithm has been proposed considering the maximum instantaneous power under the constraint of a permitted vacuum and maximum energy generation per unit length to find the model with an optimal height combination (hu, hd). The experimental prototype developed in proportion is used to verify theoretical research and conduct error analysis to establish an equation of annual energy generation for a high-rise building. Without building extra tanks, this paper presents an innovative approach to maximizing the use of energy in rain for high-rise buildings based on a siphon.

Evaluation of Combined Satellite and Radar Data Assimilation with POD-4DEnVar Method on Rainfall Forecast

Satellite and radar observations represent two fundamentally different remote sensing observation types, providing independent information for numerical weather prediction (NWP). Because the individual impact on improving forecast has previously been examined, combining these two resources of data potentially enhances the performance of weather forecast. In this study, satellite radiance, radar radial velocity and reflectivity are simultaneously assimilated with the Proper Orthogonal Decomposition (POD)-based ensemble four-dimensional variational (4DVar) assimilation method (referred to as POD-4DEnVar). The impact is evaluated on continuous severe rainfall processes occurred from June to July in 2016 and 2017. Results show that combined assimilation of satellite and radar data with POD-4DEnVar has the potential to improve weather forecast. Averaged over 22 forecasts, RMSEs indicate that though the forecast results are sensitive to different variables, generally the improvement is found in different pressure levels with assimilation. The precipitation skill scores are generally increased when assimilation is carried out. A case study is also examined to figure out the contributions to forecast improvement. Better intensity and distribution of precipitation forecast is found in the accumulated rainfall evolution with POD-4DEnVar assimilation. These improvements are attributed to the local changes in moisture, temperature and wind field. In addition, with radar data assimilation, the initial rainwater and cloud water conditions are changed directly. Both experiments can simulate the strong hydrometeor in the precipitation area, but assimilation spins up faster, strengthening the initial intensity of the heavy rainfall. Generally, the combined assimilation of satellite and radar data results in better rainfall forecast than without data assimilation.

An optimal design strategy of decentralized storage tank locations for multi-objective control of initial rainwater quality

Abstract In recent years, frequent non-point source pollution has raised serious challenges for urban water environmental management. The efficiency and cost of water quality storage tanks, which can prevent and control urban pollution effectively, are significantly affected by their locations. However, few studies have determined the location of decentralized storage tanks with consideration of the characteristics of initial rainwater quality, which has led to unsatisfactory or extravagant design. Therefore, a new design strategy is proposed to optimize the locations of water quality storage tanks using the InfoWorks ICM model in this study. It includes two basic steps. Firstly, the pollution severity of each node in the corresponding subcatchment is evaluated and ranked through the matter element analysis method and analytic hierarchy process. Secondly, all the nodes are precisely sorted by their excessive multiples using the single factor index method. Its application in the design of the decentralized storage tank locations in Fuzhou, China, proved that the proposed strategy can reduce the total volume of decentralized storage tanks to 0.38 times that of a terminal tank. The strategy presented in this study may also be useful in other research on storage tank design in urban pollution prevention and control systems.

Turbidity in Combined Sewer Sewage: An Identification of Stormwater Detention Tanks.

Combined sewer overflow remains a major threat to surface water quality. A stormwater detention tank is an effective facility to control combined sewer overflow. In this study, a new method for the selective collection of combined sewer sewage during wet weather based on real-time turbidity control is established to reduce the load of pollutants entering a river using a stormwater detention tank with a limited volume. There was a good correlation found between turbidity and the concentrations of total suspended solids (TSS) (R2 = 0.864, p < 0.05), total phosphorus (TP) (R2 = 0.661, p < 0.01), and chemical oxygen demand (COD) (R2 = 0.619, p < 0.01). This study shows that turbidity can be used to indicate the concentration of TSS, TP, and COD in the sewage of the combined sewer systems in wet weather. Based on the adopted first flush detection approach, total nitrogen (TN) and TP showed the first flush effect, whereas the first flush effect of TSS and COD was not obvious. The results show that it is impossible to effectively control combined sewer overflow by only treating the initial rainwater.