Assessment of the Drinking Water Quality in Some Wells in Al-Butana Region of Sudan

Abstract

ASSESSMENT OF DRINKING WATER QUALITY IN SOME WELLS IN AL-BUTANA REGION OF SUDAN ABDELMONEM MOHAMMED ABDELLAH AHMED ABSTRACT The groundwater availability is of necessity for human and animal life in Al-Butana region of Central Sudan. The objective of this study was to assess the quality of drinking groundwater, mainly with respect to fluoride (F-), nitrate (NO3-), electric conductivity (EC) and total dissolved solids (TDS) levels and their spatial distribution. The study also tested total hardness (TH), pH and the major cations (Ca+2, Mg+2, Na+and K+) and anions (Cl-and HCO3-) and coliform bacteria, as an indicator of faecal contamination, beside using the GIS programm to investigate the spatial distribution of the static water level (SWL), productivity, F-, NO3- and TDS. Moreover, the study investigated the effect of addition of Cymbopogon proximus (CP) (“maharaib” herb), used by the local community, on drinking water levels of F-, NO3- and TDS. The results indicated that F- concentration levels varied in different adjacent boreholes even in the same community area. About 94% of the well water samples in the construction analysis (CA) revealed F- concentrations below the maximum recommended limit of 1.5 mg/l, adopted by the Sudanese Standards and Metrology Organization (SSMO) while in the current study analysis (SA) the percentage was 88%. In spite of compliance of most of the CA and SA analyses to the local standards dental fluorosis prevalence, associated with groundwater F- concentration was observed among most of children. This study revealed that F- concentration decreased during water-pumping time in most of wells drinking water. Generally, the decrease in F- concentration was not entirely consistent with pumping rate. In both of the CA (8%) and SA (2.5%) of the investigated boreholes were completely devoid of any F-. Nitrate concentration has shown similar levels in boreholes situated in the same community area. About 79% in the CA and 50% in the SA of the investigated boreholes were devoid of any NO3- contamination. Generally, the nitrate level in the investigated SA-boreholes was well below the maximum permissible level of 50 mg/l, adopted by the SSMO, while in the CA-analysis only 2% of the boreholes fell above this level. The nitrate contamination trends indicated that NO3- concentration is continuously and variably increasing in most aquifers of the study area. The TDS concentration tended to decrease by long-term excessive pumping in the investigated boreholes of the study area. Almost all of the examined boreholes (with the exception of 6% CA and 2% SA) revealed TDS concentrations well below the maximum permissible level of 1000 mg/l adopted by the SSMO. Treating groundwater with CP at the rate of 3.3 g/l for 48 hours reduced NO3-, and at the same time increased both F- and TDS levels. Generally, the measurements of pH, EC, TH, cations and anions of the investigated well water samples comply with the recommended levels of the local, regional and international standards. Results of microbial analyses revealed that bacterial contamination of sources and sinks of well drinking water was variable, depending on the hygienic behavior. None of the well water samples taken from direct well source showed positive coliform test, while 35% of those taken from “Sabeel” (charity water stand) were positive. The tests for faecal streptococci were negative. The study suggested several recommendations for drinking groundwater quality traits that warrant further investigation