Quantification of River Nile/Quaternary Aquifer Exchanges

Quantification of River Nile/Quaternary aquifer exchanges via riverbank filtration by hydrochemical and biological indicators, Assiut, Egypt Fathy Abdalla1,2,∗ and Mohamed Shamrukh3 1King Saud University, Riyadh, Saudi Arabia. 2Geology Department, South Valley University, Qena, Egypt. 3Civil Engineering Department, Minia University, Minia, Egypt. ∗Corresponding author. e-mail: [email protected] This study approach seeks to characterize the hydraulic interactions between the Nile and the Qua- ternary aquifer via riverbank filtration (RBF) in Abu Tieg area, Assuit Governorate. The substantial removal/reduction of the most problematic substances during percolation of Nile water into abstraction wells was investigated using physico-chemical and biological indicators. Four sites with 11 municipal wells (20–750 m from the Nile) tapping the alluvial aquifer that is fed by the riverbank infiltrate were monitored. Bank-filtrated water was compared with those of the Nile and groundwater. Results showed that infiltrated Nile water ratio into the wells ranged from 39 to 80% reflecting the effect of distance from the Nile. Removal efficiency of total algal, total and faecal coliforms in bank-filtered water was 99.9%, while turbidity removal ranged from 93 to 98%. Fe, Mn and Zn in the bank-filtered water were relatively higher than those in the Nile, but were still under the allowable standards except those of Mn. LSI and WQI for the bank-filtered water indicated that the water was ranked as non-corrosive and of excellent quality. Comparison of physico-chemical and microbiological characteristics of the bank-filtered water with those of the Nile and groundwater showed the high efficiency of RBF as a treatment technology with minimal cost compared to conventional methods. 1. Introduction domestic activities. Accordingly, various pollutants could be recorded in surface waters. The fate of The importance of surface water/groundwater these substances is controlled to a large extent by exchanges via RBF which is related to the sup- filtration, dilution, sorption and biological degra- plying of potable water became a valuable tool dation during subsurface passage through river- for the long-term management of water resources. bank sediments which is known as RBF (figure 1). RBF is a natural purification process, using allu- Compared with surface water, groundwater is well vial sediments of the lateral shallow aquifers to protected against most types of pollution, recog- remove contaminants and microbial loads from sur- nized as being free of pathogenic organisms and is face water for drinking water production. Surface of relatively regular quality and temperature. Nev- waters bodies (rivers, lakes and canals) are highly ertheless, underground sewage lines and untreated exposed to pollution from discharging untreated sewage discharges may deteriorate the shallow liquid wastes from industrial, agricultural and groundwater quality especially in areas that are not Keywords. Riverbank filtration; biological indicators; turbidity; water quality index; Nile; groundwater. J. Earth Syst. Sci., DOI 10.1007/s12040-016-0755-1, 125, No. 8, December 2016, pp. 1697–1711 c Indian Academy of Sciences 1697 1698 Fathy Abdalla and Mohamed Shamrukh connected to the public sewerage system. Disposal coliform in drinking water is a strong indication of of domestic wastewater from sewage that may con- recent sewage or animal waste contamination. Coli- tain many types of disease-causing organisms into form bacteria is common in the environment and is the subsurface may introduce contaminants espe- generally not harmful but indicates that the water cially microbes, nitrate and trace elements into the may be contaminated with germs (disease-causing shallow aquifers. organisms). The use of indicator bacteria such as Pathogens are of serious concern because exces- total bacterial count, total and faecal coliforms is sive amounts of faecal coliform bacteria such as of great importance in water quality definition and Escherichia coli (E. coli) in sewage are common health risk assessment (Fleisher et al. 1998; Macler indicators of water contamination with disease and Merkel 2000; Giannoulis et al. 2005). Bacterial causing pathogens in human (diarrhea, abdominal contamination in water resources is probably from cramps and vomiting due to salmonella, cholera). infiltration of domestic or wild animal fecal waste, The presence of E. coli as a subgroup of fecal effluent from leaking septic systems or raw sewage discharges. In case of turbid water, turbidity parti- cles interfere with disinfection and form shields for viruses and bacteria providing a medium for microbial survival and growth (Avvannavar and Shrihari 2008). The presence of algae in water bodies may affect the quality of drinking water because of their production of odor and color- and taste-causing compounds. They also may interfere with some disinfectant substances used in treatment plant (Shehata et al. 2008). Nitrate as a representative of agricultural contaminant is known as a highly mobile and stable anion in shallow aerobic groundwater. Thus, it is a contaminant of concern with respect to drinking water quality and surface water eutrophication (Robertson et al. 1991; Wilhelm et al. 1994b; Valiela et al. 1997). In Egypt from Aswan to Cairo, the Nile receives Figure 1. Definition scheme for Nile and groundwater wastewater discharge from more than 124 point interaction via RBF. sources (figure 2) along the Nile banks, 67 points are Figure 2. Main sources of contamination to the River Nile; (a) Kima fertilizer factory, Aswan, (b) Qus sugar factory, Qena, (c) Oil tanker accident, Aswan, 2010, (d) Agricultural drainage discharge, Aboshosha village. Quantification of River Nile/Quaternary aquifer exchanges via RBF, Assiut, Egypt 1699 agricultural, while the rest are industrial drains. treatment more safer. Worldwide, RBF has been These discharge more than 50,00,000 m3 of water recognized (Doussan et al. 1997; Schmidt et al. 2003), that contains untreated or partially treated waste- it is widely applied in many European countries, water into Nile (Abdalla and Shamrukh 2011). especially Netherlands, Germany, France and the Accordingly, various pollutants might be recorded United States (van der Kooij et al. 1985; Stuyfzand in the river water. Source water with high dis- 1998; Kuehn and Mueller 2000; Ray et al. 2002; solved organic carbon (DOC) and bromide concen- Kim et al. 2003). In Egypt, pictures on temple trations requires special and additional treatment walls dating back to 15th century BC showed that steps. Organic contaminants may move into the the Egyptians used BF to improve the Nile water Nile water from the surrounding cultivated lands, quality (when the Nile water turned into blood wastewater discharge from villages and towns. In colour due to algal bloom) by digging around the the water treatment process, all chemical disinfec- Nile to drink (Deininger et al. 2002). tants are poisons to some extent, and the most In spite of these advantages, the RBF system common are oxidizers such as ozone and chlorine. has some limitations; the most common are plug- In Egypt, chlorine (Cl2) is the most important dis- ging/clogging of the bank filter interface which infectant used against waterborne diseases, while cause gradual reduction in production capacity and organic compounds are the most common oxidiz- remobilization of heavy metals (i.e., Fe and Mn). able contaminants. The World Health Organiza- Although, iron and manganese are not particularly tion (WHO) (2008) has established a guideline toxic, they can impair the taste of water and cause value of 5 mg/l for chlorine in drinking water. problems in pipelines, water heaters, laundry and Disinfectant by-products (DBPs) are chemicals water softeners if they are present in concentrations that result from the reaction of chlorine as a water greater than the standards. The presence of heavy disinfectant with organic substances in raw water. metals such as lead, zinc, cadmium, copper and Trihalomethanes (THMs) is the major class of chromium in drinking water are receiving increased halogenated DBPs found in nearly every chlori- attention from water treatment authorities due to nated public water supply (IARC 1991). Chlorine their poisoning effects on human. Their known combines with naturally-occurring bromide in the fatal effects include adverse impacts on mental and water, forming bromine. Like Cl2, bromine can central nervous functions. The long-term exposure react with naturally-occurring organic matter in of these metals result in physical and neurologi- water (total organic carbon – TOC) to form bromi- cal degenerative processes that cause Alzheimer’s nated organic byproducts (THMs). Complex mix- disease (ATSDR 1992; Mohod and Dhote 2013). tures of DBPs are formed when natural source In the past 10 years, few studies have been water is disinfected with oxidants, such as chlo- carried out in certain locations along the Nile val- rine and recognized their carcinogenic potential ley; they evaluate and describe the ability of RBF (Pressman et al. 2010). to remove/reduce water contaminants particularly Some epidemiological investigations have found turbidity and micro-organisms before reaching the that people who drink chlorinated surface water production well. These include Abdel-Lah and have a higher risk of developing cancer of the Shamrukh (2006); Shamrukh and Abdel-Wahab bladder, rectum and colon (Richardson et al. (2008, 2009, 2011); Abdalla and Shamrukh (2011); 2007), and adverse

Load more