PURIFICATION OF GREYWATER USING REEDBED TECHNOLOGY: EFFECT ON TDS, SO42-, PO42- AND NO3-

The validity of reedbed system using green technologies for greywater treatment was examined for consecutive two years (2013 and 2014) using three reed grass species including reed grass (Phragmites karka), reed mace (Typha elephantina) and large sedge grass (Cyperus iria). The reedbed technology was installed at Residential Colony of Sindh Agriculture University Tandojam. The seasonal effect on removal of total dissolved solids (TDS), sulphate (SO42-), phosphate (PO42-), nitrate (NO3-) was determined. The statistical analysis suggested that the effect of reed grass species on the greywater contents for TDS, SO42-, PO42-, NO3- at inlet and out let as well as on their removal was significant. The two years average removal from greywater passing reed grass species Phragmites karka, Typha elephantina and Cyperus iria was for TDS 43.65±8.48, 31.74±11.84 and 29.52±6.21%; SO42- 42.41±10.96, 34.15±9.75 and 29.50±5.23%; PO42- 80.88±7.44, 71.28 ±5.50 and 46.18±7.20%; NO3- 54.53±9.54, 42.91±8.94 and 24.54±9.32%; respectively. The TDS, SO42-, PO42- and NO32- removal was highest when greywater was treated with Phragmites karka, followed by Typha elephantina and lowest removal for all these parameters in most cases was recorded in greywater passing through Cyperus iria. The variation in removal showed association with the temperature variation during different months of the year. Phragmites karka proved to be more effective grass for maximum removal from greywater and making such waste water useful for agricultural use. The seasonal effect on the removal percentage indicated that highest TDS removal by Phragmites karka was highest in December, Typha elephantina in December and Cyperus iria in July. The sulphate removal in Greywater passing Phragmites karka was highest in December, Typha elephantina and Cyperus iria in November; while highest Phosphate removal by Phragmites karka was in March, Typha elephantina and Cyperus iria in June. Nitrate removal was highest for Phragmites karka in July; and in June for Typha elephantina and Cyperus iria species, respectively.