Drinking water quality analysis, Literature review
Chapter 1 Literature Review
This chapter presents a review of literature that is significant in answering the research questions. The review is carried out in a systematic manner with references made to empirical research carried out on the subject matter. Evidence presented in the review includes information in research articles in journals, online journals, abstracts, books as well as relevant publications.
Several studies on the physio-chemical parameters were carried out in drinking water in several parts of Nepal.
EI Kholy et al. (1997) proposed an assessment of the national water quality monitoring
program of Egypt. They stated that, the first step towards water quality management was the establishment of a monitoring network. Monitoring in the logical sense, implied watching the ongoing water characteristics and activities in order to ensure that the laws and regulations were properly enforced besides detecting trends for modelling and prediction process. They also emphasized that the design of a network must clearly define the monitoring objectives, and accordingly the necessary simplifying assumptions have to be established. Based on the assumptions made, there were many levels of design that could be applied. Their research presented the process of redesigning the water quality monitoring network of Egypt to produce the national water quality monitoring network using the statistical approach proposed by Sanders and Adrian (1978) which would have the expected confidence interval for the mean value.
Shrestha (2002) analyzed water samples from various sources and reported the physico-chemical parameters of most of the samples are within the WHO guidelines value except for conductivity (42.10%), turbidity (62.10%), and iron (82.10%).
Bajracharya et al., (2007) studied the quality of a total of 114 drinking water of the Kathmandu from different sources. The physic-chemical analysis of the samples showed 14.91%, 24.56%, 26.32%, 31.58% and 22% of water samples exceeding WHO guideline value for pH, conductivity, turbidity, iron and ammonia content respectively.
Gyawali (2007) assessed the water quality of Kathmandu, samples taken from seven different sources. Chemical analysis showed that the pH of all collected samples was found to be within limit of WHO guidelines.
Ramita Bajracharya and Naresh Kazi Tamrakar (2007) studied t
hat river habital quality index of the Manahara Rive has been scored 20–25 for the stretches except for Sano Thimi which fell within intermediate level (18), showing more pollution and environmental deterioration. Dissolved oxygen is low (5 mg/l) in Sano Thimi stretch, but is still sufficient for fishes to survive. BOD, COD, EC and coliform bacteria remarkably increase in this segment. Fish species are rare in the downstream reach of the river from the Jadibuti area most probably due to reduced dissolved oxygen and increased amount of other chemical parameters.
Diwakar et al., (2008) analyzed the drinking water of Bhaktapur Municipality Area in pre-monsoon season. She analyzed 116 water sample from different sources (public tap, well, tube well and stone spout) and the pH values of all water samples were found to lie within Nepal standard. Similarly 57(49.14%), 9 (7.76%), 56 (48.28%) and 1(0.87%) of water samp les were found to exceed Nepal standard value for conductivity, turbidity, iron and chloride content respectively. Hardness content of all water samples were within the standard whereas 6 (5.17%) samples crossed ammonia permissible level. The nitrate and arsenic content of all samples were found within permissible level.
Shuuya. M. K (2008) proposed an assessment of the impacts of pollution on water quality in the Calueque-Oshakati Canal in north-central Namibia. The study revealed that the water was unfit for drinking purposes without treatment, but for various other water uses (irrigation, fisheries and stock watering) it was suitable as it was within the NAMWATER standards and WHO guidelines for drinking water and the water quality was also within the generally accepted ranges for agriculture and fisheries use. The pollution load showed an increasing trend from upstream to down stream. This was attributed to the cumulative effects of pollution entering the Canal from the surrounding villages, grazing areas and urban centers through Overland flow and direct dumping into the Canal.
Jayana et al., (2009) assessed the status of drinking water quality of Madhyapur-Thimi. The Physico-chemical analysis of 105 water samples comprising 50 (47.61%) wells, 45 (42.82%) tap water and 10 (9.52%) stone spouts showed that pH (1.9%), conductivity (34.28%) and turbidity (16.19%) of water samples had crossed the permissible guideline values as prescribed by WHO and national standard. All samples contained nitrate values within the WHO permissible value as 12 well as national standard but hardness (2%), chloride (2.85%), iron (26.66%), ammonia (11.42%), and arsenic content (1.90%) crossed the WHO guideline value but none of the water samples crossed the national standard for arsenic.
Singkran et al. (2010) used Dissolved oxygen, biochemical oxygen demand (BOD), nitrate nitrogen, total phosphorus, faecal coliform bacteria, and suspended solids to evaluate water quality in the 5 north eastern rivers of Thailand viz., Lam Chi, Lam Pao, Lam Seaw, Loei, and Nam Oon. The mean observed values of the six water quality parameters in each river over a 5-year period (2003–2007) were used to compute the present water quality index (WQIpresent) of each river in both the wet and dry seasons. The mean observed values of the study parameters of each river by season over a 14-year period (1994–2007) were used to build a set of time series models for predicting the values of the associated parameters of each river in the following 5-year period (2008–2012). These mean predicted values were used to compute the WQIfuture for every season for each river. According to the results, the water quality at many sampling stations was in good condition. This study also revealed that the time series models with the best predictions among the stations were often not of the same type. Several time series models were used and their prediction accuracy values were compared.
Akkaraboyina and Raju (2012) assembled different water quality parameters into a single number which would lead to an easy interpretation of an index, thus providing an important tool for management and decision making purposes. Water quality was represented as the overall water quality at a specific location and specific time based on several water quality parameters. The purpose of this index was to transform the complex water quality data into information that is easily understandable and usable by general public. Eight important water parameters viz., pH, Dissolved oxygen, Electrical Conductivity, Total Dissolved Solids, Total alkalinity, Total Hardness, Calcium and Magnesium were used to estimate WQI during the study period (2009-2012) and future period (2012-2015).
Mangukiya et al. (2012) re-confirmed that Groundwater is a natural resource for drinking
water. Hence, like other natural resources, it should also be assessed regularly and people
should be made aware of the quality of drinking water. The study was aimed at assessing the water quality index (WQI) for the groundwater of Surat city. For calculating the WQI, the following 13parameters were considered: pH, total hardness, calcium, magnesium, chloride, nitrate, sulphate, total dissolved solids, iron, boron, and fluorides, COD and DO. The calculation of Water Quality Index (WQI) was done by using the Weighted Arithmetic Index method. The statistical analysis in terms of mean, standard deviation (SD), correlation and regression of obtained data were carried out using Microsoft Office Excel 2007. The results of analyses were used to suggest models for predicting water quality. Their analysis revealed that the groundwater of the area needed some degree of treatment before consumption.
A K Shrestha, N Basnet (2018) performed Physicochemical analysis of Ratuwa River with the measurement of the eighteen different parameters and the result shows that all the measured parameters are in the acceptable limit except the turbidity and BOD value that are far beyond the acceptable limit and are responsible to increase the WQI. The WQI of the Ratuwa illustrates that water is unfit for any purpose like domestic, drinking, irrigation and industrial due to its higher value of turbidity and BOD. So, proper treatment is highly needed for low risk of immediate or long-term harm.