A column design for groundwater hardness removal using cashew nut shells activated carbon with potential application in low-income communities

A Dissertation Submitted in Partial Fulfilment of the Requirements for the Degree of Master’s in Hydrology and Water Resources Engineering of the Nelson Mandela African Institution of Science and TechnologyWater hardness has been associated with various human health problems. In many developing countries, groundwater is the main source of drinking water. Water hardness has a significant impact on groundwater quality, especially in arid and semi-arid regions, leading to wasted financial investments in borehole drilling and worsening community accessibility to potable water.In this study, relatively cheap and readily available raw materials were used to remove total hardness from groundwater in a laboratory scale column setting. In thisstudy, design parameters for a filter to remove total hardness from groundwater were investigated. The optimal design parameters for the packed column were as follows: area (A) of 265.0 cm2 and diameter (d) of 18.4 cm, at a flowrate (Q) of 75.0 cm3 /min. For the field hard water flowrate of 2.0 mL/min, the optimal empty bed contact time was 70.7 min whereas the breakthrough time was about 430 min. Also, for the field hard water, the results showed that competing ions from other contaminants in groundwater lowered the materials adsorption capacity. Results from this study indicated that Cashew-nut Shell Activated Carbon may be used to adequately remove total hardness from groundwater.Using these results, a pilot filter was designed. The designed water hardness filter may provide the much-needed solution to many potable water problems facing communities in most developing countries. Keywords:Activated carbon; Cashew-nut shells; Column design; Groundwater; Hardness removal;Water filte