Investigation and ranking antiscalants and biocides in a new monitoring system for reverse osmosis desalination and benchmarking results to the conventional system

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.advisor Hesampour, Mehrdad
dc.contributor.advisor Olmos, Elsa Refaat, Mohammed 2017-05-30T05:48:03Z 2017-05-30T05:48:03Z 2017-04-24
dc.description.abstract Reverse osmosis (RO) membranes are growing to be the dominant technology for water purification applications. However, fouling is the primary obstacle affecting the RO technologies, and it forces the operator to apply higher operating pressure and use more cleaning chemicals. Therefore, the membrane research major objective is to develop complementary approaches to control fouling based on the development of effective antiscalants and biocides to control fouling and biofouling. Moreover, useful tools for quantitative online monitoring of fouling at early stages and evaluation of cleaning steps. The three experimental research chapters in this thesis are covering the two approaches. Three antiscalants were assessed in Chapter 7 to investigate the promotion of the RO recovery percentage despite the high saturation indices of feed water. The study was carried out on a model reject brine solution. Two cross-flow RO membrane units were utilised in the test. The scaling experiments were carried by circulating the feed solution through membrane modules for 90 hours in a total recycle mode at a flow rate of 48 L/h, the temperature was kept between 20 to 25 oC, and the operating pressure was controlled at 10 bars. The assessment was based on the normalised permeate flux decline and the normalised pressure drop in the absence of antiscalant dose and (2, 10 and 20 mg/L antiscalant doses). Additionally, at the end of each scaling run, membrane autopsies were carried out on a fouled membrane to provide a quantitative and quantified analysis. Two biocides were evaluated in chapter 8. The study was focusing on simulating biofouling accumulation in the cross-flow RO filtration units by utilising fresh bacterial inoculum and nutrients and exposing the system to biocide dose for cleaning. The feed water was recirculated through the system at flow rate 18 L/h in a total recycle mode for two weeks. The tank temperature was kept at 40 oC to keep the bacteria growing. The operating pressure was controlled at 10 bars. The biocide was added stepwise when the permeate flux dropped by 10-15 % of initial values. The permeate flux and normalised pressure drop were continuously monitored to verify the ability of biocide to control biofouling on RO membrane. At the end of the test, the membrane coupons were examined to determine the effect of biocide on the biofilm accumulation. The research objective of chapter 9 was to develop a prototype for real-time monitoring membrane fouling. The primary aims were to verify the device accuracy for detecting fouling of the spacer grids and membrane surface in the early phase, the device response to chemical addition (Biocide and Antiscalants), and its capability to classify and distinguish between biofouling and fouling. en
dc.format.extent 79 + 8
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.title Investigation and ranking antiscalants and biocides in a new monitoring system for reverse osmosis desalination and benchmarking results to the conventional system en
dc.type G2 Pro gradu, diplomityö fi Kemian tekniikan korkeakoulu fi
dc.subject.keyword reverse osmosis en
dc.subject.keyword desalination en
dc.subject.keyword (bio)fouling en
dc.subject.keyword antiscalants en
dc.subject.keyword biocides en
dc.subject.keyword membrane fouling simulator en
dc.identifier.urn URN:NBN:fi:aalto-201705305002
dc.programme.major Chemistry fi
dc.programme.mcode KE3001 fi
dc.type.ontasot Master's thesis en
dc.type.ontasot Diplomityö fi
dc.contributor.supervisor Alopaeus, Ville
dc.programme Master's Programme in Chemical, Biochemical and Materials Engineering fi
dc.ethesisid Aalto 8979
dc.location P1 fi

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