Biodiesel wastewater COD reduction by ceramic nanofiltration

JUAN J. TORRES; PAGLIERO, CECILIA L.; NELIO ARIEL OCHOA; MACARENA CUELLO

Santander

Congreso; 3rd ANQUE-ICCE International Congress of Chemical Engineering; 2019

ANQUE

The by-products of the industrial transesterification reaction to obtain biodiesel (BD) are mono, di and triglycerides,sodium soaps, methanol and glycerol. After several washing processes, (estimated values are in the order of 0.3-10 Lof water/L of BD) and gravimetric separations of crude BD, glycerol is the most difficult byproduct to eliminate.Previous research of our group was focus on the use of a series of polymeric nanofiltration and ultrafiltrationmembranes for purify crude biodiesel avoiding water washing [1]-[3]. However, in this work, a study was made of thetreatment of the waste generated after the wet cleaning of crude BD by using membranes technology. The permeationexperiments were carried out with a multistage centrifugal pump (grundfos CRN 2-150), a feed thermostated tank (20L), a coriollis type flowmeter (Rheonik RHE8), and a stainless steel crossflow cell for an Inopor® ceramic membrane(TiO2, 0.9 nm pore size, 10 mm OD, 7 mm ID, and a specific area of 0.024 m2/m), Fig. 1-a. A sample simulatingwastewater was made by mixing know amounts of glycerol, methanol, tribasic phosphate, sodium oleate and distilledwater to a chemical oxygen demand of ~10000 ppm, a pH = 7.7 and a conductivity value of 1500 μS/cm. Theoperating condition were: T = 30 °C, transmembrane pressure (ΔP) = 5, 10 and 15 bar, feed cross flow v = 2.3 m/s.The separation performance was evaluated from permeate flux data and the pollutants retention. The preliminaryresults (Table 1) indicate a satisfactory reduction of the effluent pollutant load. Figure 1-b shows that the fouling dueto the polarization concentration is small, while the permanent fouling is significant, as can be seen in the reductionof almost 40% of the hydraulic permeability between the clean or neat membrane and after its use, Fig. 1-c.