Control of membrane fouling by Hydrogen Sulfide (H2S) diffusion ...

Soluble Microbial Products (SMP)SMP is soluble EPS in feed water. It ismainly composed of protein, carbohydrateand total organic carbon. In our experiment,four samples were used to determine theconcentration protein and carbohydrate andfive samples for total organic carbon.Obtained results are given below:ProteinTable 1: Protein conc. (mg/l) in SMPRun C D F GNo H 2 S 38.8 8.3 0 025 ppm H 2 S 25.3 4.3 1.5 4.250 ppm H 2 S 46.3 0 0 0100 ppm H 2 S 33.8 0 14.1 0Concentration of protein in SMP has beendetermined after sparing of H 2 S in fourdifferent concentrations. Most results showthat protein concentration is very low and itdoes not vary with H 2 S concentration.CarbohydrateTable 2: Carbohydrate conc. (mg/l) in SMPRun C D F GNo H 2 S 0 7.3 6.2 23.625 ppm H 2 S 10.8 11.0 4.8 14.450 ppm H 2 S 8.3 10.9 10.3 14.8100 ppm H 2 S 12.2 13.9 13.9 16.2After diffusion of H 2 S it was not found asignificant variation of carbohydrateconcentration in SMP sample and accordingto obtained result, effect of H 2 S onconcentration of carbohydrate in SMP is notcountable.Total Organic CarbonTOC, mg/l180160140120100806040200Effect of H 2 S on TOCD F G H ISampleNo H2S sparging25 ppm H2Ssparging50 ppm H2Ssparging100 ppm H2SspargingTOC has been measured for five set ofsamples and in two test results, TOC wasnot vary significantly when applied H 2 S insludge but other three set of results showthat TOC decreases with the increase of H 2 Sdiffusion. As total organic carbon play animportant role of in fouling resistance,application of H 2 S in feed water deduce theTOC and consequently help to increase thefilterability of membrane in MBRs.ConclusionThis research works have focused on theimpact of H 2 S diffusion on membranefouling in MBR operation. ZP, pH, SMP,eEPS have been used to investigate theeffect of H 2 S application on membranefouling behavior. From the obtained result,following specific conclusions could bedrawn out:1. Application of H 2 S in feed waterassisted significantly to decrease theconcentration of eEPS and SMP TOCin sludge. It was found other studiesthat eEPS and SMP have a vital roleto enlarge the fouling resistance(Liang et al., 2007). Therefore,diffusion of H 2 S enhancedpermeability of membrane in MBRoperation by limiting foulingresistance as it reduced theconcentration of eEPS and SMPcompounds.2. It is quite clear from obtained resultsthat pH of biomass increased withthe increase of H 2 S concentration.This elevated pH value facilitates theactivities of the livingmicroorganisms which couldimprove the whole treatmentperformance.3. ZP of virgin membrane is lower thanthe fouling membrane but the effectof H 2 S application on zeta potentialis dubious because it unevenlyvaried with different concentrationof H 2 S.Fig 9: TOC of SMP at different H 2 S conc6