Application of high shear ultrafiltration along with other tertiary roots in industrial wastewater treatment

Abstract

ABSTRACT Present world is defined with geminate catastrophe of water dearth and environmental debasement. One of the key components of wastewater is oil. Severe issue of oil contaminated wastewater is the emulsion formation of oil and water. The wastewater drained to cities’ sewerage system, ultimately conveys the water to some river or sea. Thus the drainage of such oily wastewater without proper processing, will finally lead to an accretion in pollution load of water resources. Presence of oil in water hampers the aquatic environment as it restricts the avenue of sunlight through water surface, which finally constrains the aquatic life. Moreover, sustainable water reclamation attributes to the reuse and conservation of usable water for future need. Industries prime contributors in the oil contaminated wastewater generation are petroleum industries and automobile industries. During the extraction of crude petroleum from the reservoirs, large amount of effluent produced water comes out as a by-product of the process, 3:1 in ratio with extracted petroleum. To recycle this produced water in crude wells for enhanced oil recovery might be an option of the produced water management. Effect of surfactant, Sodium dodecyl benzene sulfonate (SDBS) on dynamic surface tension of produced water has been studied at different pH with varied concentration of SDBS concentration below and beyond critical micelles concentration (CMC). The air liquid interface seems to be get affected to a large extent with SDBS concentration lower than the CMC. Automobile industries also cultivate oily wastewater comprising of free oil, dispersed oil and emulsified oil. In the present work the wastewater coming out of automobile shops has tried to ameliorate through demulsification with the aid of electrolytes, high shear ultrafiltration and bioremediation. The assessment was carried out with oil-in-water (o/w) emulsion after being treated with different electrolytes and the results from the treated feed to the membrane were compared with the untreated feed to the membrane. Two high sheared modules, namely, a turbine flow membrane module (TFMM) and a radial flow membrane module (RFMM), were compared to understand the superlative performance in removing oil from its o/w emulsion (either treated or untreated) using a 25 kDa polysulfone (PSf) membrane at different temperatures and pressures. It was observed that the permeate flux is 30–38% higher in all the cases with TFMM, depending on operating temperature and pressure. Furthermore, among the electrolytes used, 15% sodium sulfate (Na2SO4) solution shows a maximum of 26% oil removal from emulsion, while TFMM shows a 45% higher permeate flux compared to RFMM with this pretreated feed compared to the module. In this present study an attempt was made towards the bioremediation of spent oil from waste stream. Oil degrading bacteria isolated from contaminated waterways using enrichment culture technique. Among several isolated strains, two strains named as “A3” and “A4” were found effective in degrading hydrocarbons. Further, in between these two strains, A3 showed 41 % removal of spent oil, at 35°C and pH 8, which was almost 5% more compared to strain called A4. The growth study for both the strains was done at 120 rpm for 30 days in Bushnell-Haas (BH) media. Strain called A3 was further studied towards the remediation of o/w emulsion for 7 days preserving other previous conditions, which showed around 21% removal of oil from emulsion. The result was found comparable to the free oil at the same parametric conditions for strain called A3.