Pilot Scale Study on Pressure Filtration System for Evaluation of Filtralite Filter Media

Abstract

Filtration is one of the principal unit operation used for the supplemental removal of suspended solids (including particulate BOD) and even for the removal of pathogens from water and wastewater. Conventionally, sand and occasionally anthracite have been used as a filter media. But these days many other synthetic filter media available in the market for use in place of the conventionally used sand. Suppliers claim many more things in addition to the removal suspended solids. Removal of pathogens, BOD, odours and smells, heavy metals are among these claims even in the rapid gravity filtration modes. However wide spread use of these synthetic media will depend on demonstrating the filtration process and proving the claims. Filtralite one such synthetic medium claimed to have the capabilities beyond that of sand and/or anthracite. Supplier of this medium in India has shown interest in evaluating this medium and developed specifications and design parameters for the rapid gravity filters and the pressure filter alternatives. Consequent this pilot scale evaluation of the filtration process using filtralite as medium on synthetic water/wastewater has been planned. Modular pilot scale filtration systems with all the provisions for necessary experimentation and monitoring have been designed and articulated. The articulated systems were supposed to be used for the evaluation of 8 different types of filtralite media vis-à-vis the conventional media, sand and anthracite. In the present study two pilot scale filtration systems was designed and articulated. Test runs were carried out for making the filtration, the filter backwashing, and the filtration process monitoring and analysis standardized. To begin with all the types of filtralite media, conventional sand and anthracite media were characterized. The filtration system was assembled using one of the filtralite media, MC 0.8-1.6, and three filter runs were carried out, the filtration process was monitored and the monitored data was analysed. The results obtained are presented in this report. Filtration was carried out at a required rate of 20m/hr. Raw water modified through dosing bentonite clay for the desired turbidity was filtered. Results showed that the backwashing needs to be done after 12 hours of run as the turbidity and overall pressure increases at that time.