Treatment of Oily Waters Using Peat

Abstract

Abstract Peat offers itself as an effective medium in the treatment of oily waters, due to its known capacity to remove oil and its abundant availability in Canada. Horticultural peat produced by the Saskatchewan Minerals was used in this study to assess its potential for the removal of oil from various oil-in-water emulsions. The representative oil-in-water emulsions included the following: (1) Medium viscous (130 cP) standard mineral oil (SMO), (2) low viscous (50 cP) Midale crude oil (MCO), cutting oil (CO) and (4) refinery effluent (RE). Batch kinetic studies were conducted to identify equilibrium time and isotherm patterns. The adsorption of oil by peat was well represented by the BET isotherm compared to the Langmuir and the Freundlich equations. Column studies were conducted using a 100 mm diameter, 600 mm long acrylic pipe with 300 mm depth peat bed. Initially eight-hour tests were run for three different flow rates of 12, 48 and 300 mL/min (2.13, 8.52 and 53.28 m/d). These column studies showed that removal of oil varied between 34 and 99 percent depending upon the influent oil concentration, the type of emulsion, and the flow rate. Breakthrough studies were undertaken for an optimum flow rate of 50 mL/min (8.88 m/d) for SMO and MCO and 25 mL/min (4.44 m/d) for CO and RE to assess the ultimate capacity of peat under dynamic conditions. The data obtained from breakthrough studies were applied to scale-up and kinetic models to estimate the amount of peat required to remove oil from a flow rate of 150 m3/d of oily waters.