Application of Water Quality Index to Monitor Ground Water Quality: A Case Study in Colombo Catchment of Sri Lanka

Deterioration of groundwater quality directly threatens the livability of a community. Sri Lanka is currently undergoing a rapid increase in the demand for water, particularly for urban/rural water supplies, irrigated agriculture and in the industrial sector, exerting a considerable pressure on the available groundwater resources. This study was carried out to assess the status of groundwater quality around the Parliament Lake, in Colombo catchment, Sri Lanka by employing the Canadian Council of Ministers of the Environment (CCME) Water Quality Index (WQI) from September 2016 to September 2017 (one year). The objective of the study was to assess the suitability of groundwater in the study area as potable water through CCME WQI. Water samples were collected from thirty-four (34) locations including twenty-six (26) domestic shallow wells and eight (08) deep wells. The in-situ measurements of the parameters pH, Temperature, Dissolved Oxygen, Total Dissolved Solids, Electrical Conductivity, Salinity were conducted monthly while the laboratory testing for Ammonia, Nitrate, Phosphate, Chemical Oxygen Demand, Biological Oxygen Demand were conducted twice for fifteen (15) selected wells during the project period. CCME WQI was calculated taking pH, Temperature, Dissolved Oxygen, Total Dissolved Solids, and Electrical Conductivity into account. Results revealed Nitrate, Sulphate and Calcium levels of both shallow and deep wells were within the Maximum Permissible Levels in the SLS 614, 1,983 drinking water standards. The Nitrate levels of both shallow and deep wells were comparatively high in the dry season and in contrast, Phosphate, Calcium, Sulphate and BOD values in most the shallow wells and deep wells were comparatively high in the wet season. High Ammonia levels of five (05) out of fifteen (15) selected shallow wells exceeded the maximum permissible level given in standards. The highest COD levels in dry and wet seasons were recorded 42.0 mg/l and 88.0 mg/l respectively indicating that the water is unsuitable for drinking. According to the CCME WQI, the quality of twenty three (23) out of twenty seven (27) shallow wells were in the “Marginal” level (85.19%) and one in “Poor” condition (3.70%). The water quality of these twenty four (24) shallow wells is frequently endangered or deteriorated. The CCME-WQI values indicated that the water in four Deep Wells is in good quality (57.14%), whereas water in two deep wells is in Marginal level quality. Present study revealed that GW 20, GW 08, GW 09, GW 10 and GW 28 have deteriorating water quality with downgrading parameters of Electrical Conductivity, Salinity, and Total Dissolved Solids. Accordingly, it is proposed to carry out a well-planned groundwater quality management mechanism to avoid further pollution. In addition, detail studies to identify the causes of ground water pollution should be conducted.Keywords: Ground water quality, Pollution, Colombo catchment, Water quality inde

Deflourination of drinking water using layered double Hydroxides

Safe drinking water is one of the prerequisites for a healthy life. In Sri Lanka 70% of the population satisfy their water needs from ground water and as a result majority of them suffer from water related problems. One of the pertaining problems prevailing in the dry zone of Sri Lanka is the presence of elevated levels of fluoride ions in drinking water leading to many health related problems. Many studies have been carried out to address the issue however little success has been reported up to date. This study focuses on suggesting a nanotechnology based solution to deflourinate drinking water in the dry zone, Sri Lanka, for domestic water tanks or as a region water purification solution. Layered double hydroxides (LDHs) which readily undergo anion exchange reactions have been used as a suitable candidate for deflourination. The study further concentrates on the regeneration of the material after removal of fluoride ions without releasing flouride ions back in to the water cycle

Two new plant nutrient nanocomposites based on urea coated hydroxyapatite: Efficacy and plant uptake

Macronutrient delivery to plants, particularly nitrogen, is problematic because of losses occurring during fertilization. Currently, nanotechnology is being considered as a solution to improving nutrient use efficiency. In this study, we report the synthesis and plant uptake of two plant nutrient nanocomposites based on urea coated hydroxyapatite (UHA) and potassium encapsulated into (i) a nanoclay, montmorillonite (MMT) or (ii) cavities present in Gliricidia sepium stem resulting in a wood chip containing macronutrients. Soil leaching behaviour, efficacy and plant uptake of the nutrients were tested in a pot experiment using Festuca arundinacea during a period of 60 weeks. Two nanocomposites displayed slow release behaviour particularly for nitrogen, in soil leaching tests compared to the conventional formulations. Both nanoformulations displayed efficient plant nutrient uptake highlighting the improved nutrient use efficiency. These data clearly revealed that urea fabricated into its nanoscale provide platform for development of efficient fertilizer formulations

Urea–hydroxyapatite-montmorillonite nanohybrid composites as slow release nitrogen compositions

Nanohybrid composite was developed by the encapsulation of urea modified hydroxyapatite nanoparticles into the nanolayers of montmorillonite. The nanohybrid composites were synthesized by two approaches; solution phase synthesis and liquid assisted grinding techniques and were tested for their slow release nitrogen in soil. The characterization results revealed the successful realization of a nanohybrid containing urea modified hydroxyapatite nanoparticles encapsulated in montmorillonite. The release behavior of urea in different pH values indicated a slow and sustained release of nitrogen. The rate of release of N was significantly lower in the nanohybrid composite prepared using solvent assisted grinding techniques. Pot trials conducted using Oryza sativa (rice) demonstrated a significant yield enhancement with the novel plant nutrient system. Montmorillonite nanohybrid composite thus prepared can be used as an environmentally friendly fertilizer formulation which could be extended to solve one of the major problems faced in the global fertilization of low nitrogen use efficiency in agriculture