Management of grey water with bio-beds using phytotechnology

Abstract

The waste water treatment trial has been carried out at Department of Environmental Management, Bharathidasan University, Tiruchirappalli, Tamil Nadu, India. The aim of the trial was to evolve a suitable user friendly treatment system, for handling the domestic liquid waste at the point of generation; subsequent reuse in flushing the toilets, irrigating gardens, etc. To achieve these objectives, four different bio beds were designed and filled with pea gravel, sand, clay, red soil and charcoal in different ratios. All the bio-beds (excluding bio-bed 4), were planted with plant species viz., Lipia nodiflora (bio-beds 1 and 2) and Vettiver Zizanoides (bio-bed 3). Physico-chemical properties of the water at both before and after the treatment were compared and reductions percentages were calculated for major parameters. The test results gave concrete evidence for a reduction in the biological oxygen demand (89 %), chemical oxygen demand (81 %), carbonate (100 %), sulphate (77 %), sodium (77 %) and potassium (74 %). It is found that continuous vertical flow based constructed wetland system can be used for decentralized management of grey water in institutions. This filter bed method is natural, simple and cost-effective.