The average groundwater extraction from Murunkan well field, Mannar, is around 3.4 MCM/year, and it was triggered by extensive development projects and resettlements that took place in the last decade. Manganese and Iron variations in Murunkan groundwater reported during some periods created various operational and aesthetic issues in the potable water supply. This study is focused on treating iron and manganese in groundwater using chlorination and Rapid Sand Filtration (RSF) techniques. Pebble layers, height of 205 mm with the particle sizes ranging from 2-25 mm, were filled at the bottom of RSF model filter. Filter media, height of 700 mm with 0.45 mm effective size (D10) and a uniformity coefficient (Cu) of 1.33, was placed above the pebble layers. The filter was operated continuously for 15 days, and influent and effluent water samples were collected from 15 trials. Filter backwashing was performed after every two trials to maintain a consistent filtration rate. Raw water pH values ranged from 6.74 – 7.48. Chlorine solution (1.08-1.26 ppm) was added at the inlet point, and a 2.88 m water column was maintained, allowing adequate mixing and oxidation time. The results revealed that average removals of iron and manganese as 60% and 73%, respectively, while maximum removals of 93% and 91% were observed for iron and manganese, respectively.

Home gardening is identified as one of the remedial measures for food security issues caused by the economic downfall in Sri Lanka. Home gardening contributes to household food security by providing direct access to food. Further, it is also an important source of supplementary income for households. The appropriate function of a pressurized agriculture pipe network system is vital to supply sufficient quantity of water to the plants at sufficient pressure through the sprinkler output. Despite this, very few computer simulation techniques studied the optimization for the case of the home gardening agricultural pipe system. In this study, the WaterGEMS V8i software simulator was used and hydraulic analyses were conducted to design an optimal pressurized agriculture pipe network suitable for home gardening in the Vavuniya area. The water flow rate at sprinkler outlet points for chilli and onion were considered 600 L/h and 325 L/h respectively.

The appropriate operation of a water distribution network (WDN) of any water supply scheme is vital to supply sufficient potable water to consumers at sufficient pressure. However, the performance of the WDN may vary from the original design in the long run. In this study, a WDN network model was built using WaterGEMS and WaterCAD computer simulators, and hydraulic analyses were conducted to obtain an optimal WDN for a community water supply scheme of a village in Sri Lanka. A series of steps such as; selection of models, network representation, simulation of network, problem identification, network configuration finalization, and results analysis were carried out in developing the WDN simulation model. The hydraulic parameters such as pressure, flow velocity, and flow rate were analyzed under extended period simulation. The result indicated that the nodal pressure head in the junctions (100%) is above the required pressure level of 10 meters H2O, which is adequate for the effective performance of the water distribution system (WDS) during peak and off-peak demand hours. The elevated water tower was optimized with a 10 m height to supply water at satisfactory pressure. Nodal pressure is negatively correlated with ground elevation. The flow velocity was observed within the range of 0.1-0.4 m/s in 67% of the pipe network, while 17% of the pipe network velocity was below 0.1 m/s. The low daily water demand of the small community could be the reason for the low-velocity scenario, which shall lead to silt deposition in the pipelines; hence frequent line washout to eliminate the silt deposition in the system is recommended. The WDN was designed for optimized pipe sizes with availability in the market.