A COMPARATIVE STUDY OF WASTEWATER TREATMENT WITH DIFFERENT VARIANTS OF CONSTRUCTED HYBRID WETLANDS by Simranjit Singh
Abstract
The demand of water is increasing, with rise in population. To tackle it, the government agencies are taking various steps to recycle wastewater and put this treated wastewater into various uses. Constructed wetlands or man-made wetlands are one of the leading wastewater treatment systems. It is very sustainable, cost effective and simple. In present study, the kitchen wastewater and domestic wastewater is treated in four different variants of hybrid wetlands (combination of vertical beds and horizontal beds as subsurface type flow constructed wetlands) and the removal efficiency of wastewater characteristics i.e. BOD, COD, TSS, Total nitrogen (nitrates, ammoniacal and organic nitrogen) and Total Phosphorus were compared with these different variants and a previous study in which single VFCW is used to treat same wastewater in same conditions using same plant. The detention period was 3hrs for hybrid systems. Phragmitesaustraliswas used as vegetation on both cells of hybrid system. Study period was February to April (25˚C to 44˚C), 10% of water is lost through evapotranspiration at 3hours HRT whereas it is almost 39% in case of 24hour HRT. The testing in hybrid system was conducted in vertical to horizontal flow type system, connected in series
and vice versa, in which the substrate in horizontal bed was local alluvial soil in first phase and sand in second phase of study. The vertical units were provided with aeration pipe of 2.5cm diameter from top to bottom of the bed and the upper layer is of local alluvial soil whereas in previous study of VFCW, no aeration pipe is provided and the upper sub substrate is of fine clay. Out of the four designs of hybrid setup, the system with horizontal to vertical flow type that too with sand bed as substrate in horizontal, gives maximum efficiency for all the parameters except for total phosphorus. For TP the efficiency for all the systems more or less remains same. All the hybrid systems as well as single VFCW are very effective in stabilizing the pH of wastewater in the range of 7.45-7.57.
