Development of a cost-effective activated carbon incorporated sand gravel filter for rainwater treatment

Authors

  • P.H. Ashanka National Building Research Organization
  • M.A.A. Prasasthi Center for Water Quality and Algae Research, Department of Zoology, University of Sri Jayewardenepura
  • R.R.P.N. Ratnayake Planning and Design Division, National Water Supplies and Drainage Board of Sri Lanka
  • M.M. Pathmalal Center for Water Quality and Algae Research, Department of Zoology, University of Sri Jayewardenepura
  • F.S. Idroos Center for Water Quality and Algae Research, Department of Zoology, University of Sri Jayewardenepura

Abstract

Drought-related water stress conditions are prevailing in the country due to the rainfall variability and pollution of water sources by agrochemicals. Roof Rainwater Harvesting Systems (RRHS) are promising solutions to address the increasing demand for drinking water, especially in drought-stricken areas. However, RRHS is not popularized among most communities mainly due to suspicion of rainwater quality. Thus, the present study focuses on assessing the efficiency of a simple, slow sand filtration system integrated with an activated carbon layer for rainwater treatment. The sand gravel filter was developed cooperating with a Corn cob-based activated carbon layer. The filter includes fine sand, activated charcoal, coarse sand, and gravel from top to bottom. Rainwater samples were collected from five locations using the storage vessels of RRHS in the Medawachchiya area in the Anuradhapura district. Harvested rainwater was analyzed using the standards methods (APHA). Physio-chemical and microbiological parameters of water were measured before and after the treatment through the activated carbon incorporated sand-gravel filter. The results showed that the filter removed 99.9% and 95.5 % of faecal and total coliform in rainwater samples.  Turbidity, nitrate, and nitrite concentrations were reduced by 83.1%, 82.9%, and 90.7%. pH, Total Dissolved Solids (TDS), Electrical Conductivity (EC), Chloride, Sulphate, Total Hardness (TH), Total alkalinity (TA) and free Ammonia have been reduced by 7.6%, 34.5%, 34.9%, 49.1%, 12.5%, 51.1%, 57.2%, and 33.7% respectively after passing through the filter. Color, free iron, and residual chlorine of stored rainwater were under the Sri Lanka Standard Institute (SLSI) accepted range before passing through the filter. Therefore, the present study results showed that the activated carbon incorporated sand filters to the RRHS could be recommended as a sustainable solution to upgrade the drinking water quality of harvested rainwater.

 

KEYWORDS: Sand gravel filter, Activated carbon, Roof Rainwater Harvesting Systems (RRHS), Water quality

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Published

2022-07-15

Issue

Vol. 9 No. 2 (2022): International Journal of Multidisciplinary Studies

Section

Articles