Variation of rainwater quality in Visakhapatnam

The electrical conductance (EC) of rain waters at Visakhapatnam is studied for a three year period of 1991-93. Lower amounts of rainfall (RF) record higher conductivity values and vice-versa due to dilution process of the amount of rain. EC/RF ratios decrease from summer months to monsoon as the accumulation of salts during dry periods is drained off with the progress of monsoon rains. Visakhapatnam records higher ionic contents than other stations in India due to highly polluted industrial atmosphere. The ionic contents for Ca, Na, K and a are possibly increasing with time at Visakhapatnam.

The role of the mahogany tree (Swietenia macrophylla King) on quantity and quality of water that fall below the canopy

Mahogany trees (Swietenia macrophylla) are often planted in urban forests area. This shady-crowned tree has a role in controlling the quantity and quality of rainwater that falls to the ground. Mahogany trees also affect the quality of rainwater through interception, fall, and stemflow. The purpose of this research was to determine the impact of the interception process, such as throughfall and stemflow, on changes in rainwater quality of the mahogany tree. The Data that needed to be measured were tree dimension, rainfall interception, and rainwater quality. Interception measurement was performed by calculating the number of throughfall and stemflow in one month-measurement. While the measurement of rainwater quality was measured once in the laboratory. These water quality measurements include Electrical Conductivity (EC), hardness, the content of Elements Ca, Mg, Na and K, and pH concentrations. The results based on the total area of the crown showed that mahogany had an interception value of 18.088%. In the throughfall measurement, the mahogany has a throughfall of 81.799%, while the amount of the stemflow is only 0.113%. The correlation of interception values, throughfall, and stemflow with rainfall are in general positively correlated. That means the higher rainfall water will increase the number of interception, throughfall, and stemflow. The results on water quality measurement explain that Ec value in rainwater interception was increased compared to water produced from rainfall in mahogany trees. It also has the same condition in hardness measurement. In pH measurements, the interception of rainwater has less pH when compared to direct rainfall water. In addition, the content of Elements Ca, Mg, K, and Na in Stemflow and Throughfall water have more numbers than rainfall itself.

Evaluation of Rainwater Quality in Different Areas of Dhaka City

Since rainwater harvesting system was assessed to be potential in residential, industrial, educational and other institutions so the study was focused on the rainwater quality of samples collected from rooftop surface runoff of different locations of Dhaka city which is the 2nd most polluted city of the world. Locations were based upon residential, commercial, industrial zone within the area, motorized vehicles use, population, construction works etc. The rooftops were taken mainly of concrete made rooftops and within a single area 03 locations were chosen and a sample of rainwater was collected from a tin made rooftop within that area. The main purpose of this assessment was to compare the rainwater quality of different locations with the drinking water quality standards of Bangladesh and World Health Organization (WHO) in order to observe whether the water needs of further treatment or not for potable use. The samples were checked of physical (Turbidity) and chemical (pH, Electric Conductivity, Total Dissolved Solids, Nitrate, Nitrite, Sulfate, Chloride & Fluoride) characteristics of water quality. In terms of pH, Nitrate and Fluoride values, there were significant imbalance with the standards and thus required treatment for potable use. And other parameters were within the standards.

Reusable rainwater quality at the Ikorodu area of Lagos, Nigeria: impact of first-flush and household treatment techniques

Water scarcity is a huge problem in Africa, and hence rainwater becomes a crucial water source for fulfilling basic human needs. However, less attention has been given by African countries to the effectiveness of common rainwater treatments to ensure the population's health. This study investigates the impact of different household treatment techniques (HHTTs), i.e. treatments by chlorine, boiling, alum, and combination of alum and chlorine, on its storage system using a case study at the Ikorodu area of Lagos state, which is a rural area in Nigeria. The first-flush quality has been particularly studied here, where the microbial reduction through its practice has been examined from five different roofs. One of the investigated roofs was from a residential building, and four were constructed for the purpose of this study. In this study, the physical parameters (i.e. total suspended solids and turbidity) and the microbial parameters (i.e. total coliform and Escherichia coli) of the collected rainwater have been investigated. From the results, it has been observed that: (1) the water quality at the free phase zone is better than that at the tank's bottom; (2) the combination of chlorine and alum gives the best rainwater quality after comparing the application of different HHTTs; and (3) a reduction of about 40% from the original contaminant load occurs in every 1 mm diversion.

Study on Acidity and Neutralizing Ability of Ions in the Chemical Composition of Rainwater

The acidity in rainwater is mainly controlled by the presence of H2SO4, HNO3 in combination with the ability to neutralize cations in rainwater. pH is an important value in the evaluation of acidity in rainwater. The research used a series of rainwater quality monitoring data from 2005 to 2018 in Vietnam. The research showed that the average pH distribution at 23 stations ranged from 5.83 ± 0.62. The rains with pH <5.6 appear in all years at the research stations. Considering the ability of acid neutralizing to various ions shows that Ca2+ is the main contributor to acid neutralization processes in rainwater, followed by Mg2 +, NH4+, and K+. While Ca2+ always play the highest acid neutralizing role at all stations; Depending on each station, Mg2+ and NH4+ ions play a role in neutralizing acidity in rainwater. The research also shows a match between the trend of H+ concentration and the tendency of cations to contribute to acid neutralization in rainwater.

Assessing Rainwater Quality Treated via a Green Roof System

The shortage of water worldwide is increasingly worrying. Studies in the field suggest that sustainable water resource management via water recycling is fundamental to alleviate the issue. The use of rainwater is an important alternative source that must be considered, mainly, in the water crisis facing the planet. When integrated with the concept of green roofs, the capturing and treatment of rainwater in these structures becomes an even more ecological and sustainable practice. The water drained by the roof can be used for non-potable uses, such as flushing toilet bowls. One of the main concerns when using rainwater, even for non-potable uses, is the quality of the water available, so as not to put users' health at risk. In this way, the present work proposes to experimentally analyze the quality of rainwater drained in a green roof prototype for reuse purposes. The green roof prototype was installed on an experimental bench. After each rain event (four in total), two water samples were collected in the following situations: rainwater captured directly by a container next to the bench, and rainwater drained by the green roof prototype, captured by a container through existing drains at the base of the prototype. The analyzes of the collected samples were carried out at the Environmental Engineering Laboratory (LEMA / UFRJ) and performed according to the Standard Methods for the Examination of Water and Wastewater. Specifically, the experiments examine physicochemical and biological parameters following a rain event on a green roof prototype for sanitary use. Experimental results that were observed and analyzed include color, turbidity, pH, ammonia nitrogen, nitrite, nitrate, orthophosphate, total coliforms, and thermotolerant coliforms to indicate the rainwater quality from green roofs. The majority of parameters assessed were within the value thresholds indicated by the Brazilian standards, while the results of orthophosphate, fecal coliforms, color, and turbidity were not. The greatest divergence is in the concentration of orthophosphate, where a concentration of 10.88mg/L was obtained in this experimental study while other authors present values ​​of 0.1 and 0.01mg/L. Total coliforms also presented high values, but within the expected range. Comparisons with technical documents and international references related to water quality to identify possibilities of the use of rainwater were also conducted. Results indicate that the water quality has the same order of quantity for turbidity, nitrite, and ammonia nitrogen parameters across the standards. Based on such observations, filtration and disinfection processes are therefore required in the green roof system for the use of rainwater for sanitary. Finally, the experimental study of rainwater quality on the green roof presented similar results comparing with international references. The use of green roofs combined with the use of rainwater demonstrates the potential and benefits as an alternative to face the water crisis.

Spatial-temporal variation and modeling of rainwater quality

Rainwater harvesting (RWH) is an alternative to the problem of water scarcity. However, its quality must be analyzed before its use, so that it does not represent any danger to the consumer. Thus, the objective of this paper was to analyze the spatial-temporal variation of water quality of rainwater in two cities and observe whether its parameters meet the norm related to the subject. In addition, the concentration of total suspended solids (TSS) that flow into the drainage system was also simulated. Rainwater samples were collected at several points in Congonhas and Ouro Branco - MG, over a period of two years. The results showed that there was spatial-temporal variation in water quality. There were points where the quality met the standard in some moments and did not meet in others, due to its temporal variation. It was also observed that the catchment surface influenced the quality of rainwater, so that the water that came into contact with the roof had its quality deteriorated, at first. However, throughout the rainy event, the quality improved, but at certain times, it was not enough to meet the standard. The rainwater quality simulation, carried out at SWMM, showed high concentrations of TSS, which were higher to that allowed for launching into receiving bodies.

Potential for Potable Water Savings Due to Rainwater Use in a Precast Concrete Factory

The objective of this paper was to assess the potential for potable water savings due to rainwater use in a precast concrete factory in southern Brazil. The economic feasibility and the rainwater quality were also assessed. The current water consumption, future water demand, and rainwater demand in the factory were estimated. The future demand considered was two times higher than the current water consumption since there were plans to increase the production. Three scenarios were then simulated using the computer programme Netuno. The ideal rainwater tank capacity, the potential for potable water savings, and the economic feasibility analysis for each scenario were estimated. Samples of rainwater were collected in the factory and tested for quality for manufacturing precast concrete. For a rainwater tank capacity equal to 25,000 L, the potential for potable water savings for the first scenario was 55.4%, but the first scenario was considered economically unfeasible. For the same tank capacity, the second and third scenarios presented viable results regarding potable water savings and payback. As for the rainwater quality, it was proven to be adequate for manufacturing precast concrete. The main conclusion was that rainwater can be used to manufacture precast concrete in the factory studied herein.