Humic Acid removal and fouling using tubular ceramic micro filtration Essay

Humic Acid removal and fouling using tubular ceramic micro filtration membranes combined with coagulation and adsorption - Essay Example result in either increased flux (for operation at constant pressure) or decreased feed pressure requirements (for operation at constant flux); the converse effect results from colder feedwater.† (Cheryan, 1998) Consequently, temperature is an important consideration in the conceptual design phase, because changes in feedwater temperature over the year may necessitate additional membrane area to maintain the required system capacity, depending on the maximum TMP of the membranes, seasonal water demand, and other site-specific factors. When considering temperature effects on MF/UF membranes, the flux is typically normalized to a reference temperature of 20 °C. (Cho et al., 283-298, 2000) Typical units for flux are gallons of water per square foot of membrane area per day or litters of water per square meter of membrane area per hour. The pore density (P^sub pore^) is the number of pores per unit of membrane area, r is the pore radius, Ï„ is the tortuosity factor, and Δz is the pore length. Thus, the resistance to pure water transport across a clean membrane is expected to increase with increasing tortuosity and thickness and with decreasing pore density and pore radius (with a strongly influencing inverse 4th power relationship). An important operational factor that can strongly influence the flux is the foulants that accumulate over a filtration cycle (reversible fouling), between cleaning intervals (reversible fouling), and over the life of a membrane module (irreversible fouling). This fouling can take several forms: particulate/colloidal fouling, organic fouling, and/or bio fouling. Fouling results in the gradual reduction in flux (for constant pressure operation) or increase in TMP (for constant flux operation) because of adsorption or deposition of contaminants either within the pores or on the surface of the membrane. (Hicke, 187–196, 2002) In Eq 1, fouling is incorporated by expanding the resistance term to include additive factors to account for the