?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F19084%2F&rft.title=Control+of+mineral+scaling+in+power+plant+recirculating+cooling+systems+using+treated+municipal+wastewater&rft.creator=Wenshi%2C+Liu&rft.description=The+global+energy+demand+is+projected+to+increase+by+77%25+from+2006+to+2030+along+with+a+projected+38%25+increase+in+freshwater+withdrawal+for+cooling+in+power+industry.+Finding+alternative+sources+of+water+for+cooling+has+become+essential+for+future+energy+generation+in+thermoelectric+power+plants+because+of+water+scarcity+in+many+parts+of+the+US.+Treated+municipal+wastewater+is+considered+as+one+of+the+most+promising+alternative+water+sources+because+of+its+geographic+distribution+and+abundant+quantity.+However%2C+its+impaired+water+quality+makes+the+cooling+tower+management+more+challenging.+Therefore%2C+effective+approaches+are+required+to+prevent+scaling%2C+corrosion%2C+and+biological+growth+to+promote+the+reuse+of+treated+municipal+wastewater+as+cooling+water+in+power+plants.+%0D%0AThis+study+focuses+on+understanding+mineral+scale+formation+and+developing+effective+mitigation+methods+when+using+tertiary+treated+municipal+wastewater+as+power+plant+cooling+makeup.+Two+types+of+tertiary-treated+municipal+wastewater+that+were+evaluated+included+secondary-treated+water+with+pH+adjustment+(MWW_pH)+and+water+from+secondary-treatment+followed+by+nitrification+and+sand+filtration+(MWW_NF).+Laboratory-scale+studies+and+pilot-scale+cooling+systems+were+used+to+evaluate+mineral+scaling+formation+and+inhibition+on+non-heated+surfaces+(e.g.%2C+pipelines%2C+tower+packing%2C+etc.)+under+conditions+relevant+to+full-scale+cooling+systems.+Results+showed+that+pH+adjustment+to+7.8+plus+the+addition+of+5+ppm+polymaleic+acid+(PMA)+could+reduce+the+scaling+significantly+with+MWW_pH.+MWW_NF+exhibited+little+scaling+potential%2C+which+is+related+in+part+to+the+lower+pH+and+alkalinity+in+this+water.+Amorphous+calcium+phosphate+(ACP)+was+the+primary+form+of+mineral+scale+on+non-heated+surface+with+the+above+two-types+of+tertiary-treated+municipal+wastewater.+%0D%0AA+bench-scale+experimental+system+was+designed+to+simulate+the+condenser+surface+to+study+the+impacts+of+mineral+scaling+on+the+heated+surfaces+and+the+effectiveness+of+proposed+scaling+control+strategies+under+these+conditions.+Heated+surface+favored+the+formation+of+hydroxyapatite+(HAP)%2C+the+most+thermodynamically+stable+calcium+phosphate%2C+was+the+main+reason+for+the+crystalline+fouling+with+MWW_pH+at+pH+7.8.+10+ppm+PMA+addition+could+suppress+the+crystalline+fouling+of+MWW_pH+at+7.8+to+a+low+level+by+inhibiting+the+transformation+of+amorphous+calcium+phosphate+to+hydroxyapatite+during+the+test+period.+Significant+crystalline+fouling+was+identified+with+MWW_NF+at+pH+7.2+while+pH+adjustment+to+7.8+resulted+in+negligible+fouling.+%0D%0AThe+impact+of+flow+velocity+on+particle+deposition+was+analyzed+in+a+quantitative+model%2C+showing+positive+deposition+potential+for+bulk+precipitates+at+flow+velocity+of+0.5+and+0.4+m%2Fs+while+little+particulate+fouling+was+theoretically+predicted+at+0.6+m%2Fs+in+the+test+situation.+Bench-scale+studies+were+consistent+the+model+prediction%2C+confirming+that+the+model+could+be+used+to+identify+optimal+hydrodynamic+conditions+to+control+depositions+of+bulk+precipitates.+%0D%0AThe+mechanism+of+calcium+phosphate+scale+control+by+common+antiscalants+included+PMA+and+1-hydroxyethane+1%2C1-diphosphonic+acid+(HEDP)+was+elucidated+to+provide+scientific+background+for+the+effective+scaling+mitigation+when+treated+municipal+wastewater+is+used+as+make-up+in+thermoelectric+power+plant+cooling+systems.+Both+PMA+and+HEDP+inhibited+the+transformation+of+ACP+to+HAP+by+preventing+the+aggregation+of+ACP+particles.+However%2C+PMA+dispersed+the+ACP+particles+mainly+through+electrostatic+repulsive+force+while+hydration+force+was+hypothesized+to+be+the+reason+for+the+function+of+HEDP+in+dispersion.%0D%0AThe+key+findings+of+this+study+indicate+that+it+is+possible+to+control+mineral+scaling+through+direct+chemical+addition+at+proper+operating+conditions+when+treated+municipal+wastewater+is+used+as+makeup+water+in+the+recirculating+cooling+system.+This+study+not+only+evaluated+scaling+control+methods+in+cooling+systems%2C+but+also+revealed+the+fundamentals+of+scaling+formation+and+inhibition.%0D%0A&rft.date=2013-09-25&rft.type=University+of+Pittsburgh+ETD&rft.type=PeerReviewed&rft.format=application%2Fpdf&rft.language=en&rft.identifier=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F19084%2F1%2FLiuWS_ETDPITT2013.pdf&rft.identifier=++Wenshi%2C+Liu++(2013)+Control+of+mineral+scaling+in+power+plant+recirculating+cooling+systems+using+treated+municipal+wastewater.++Doctoral+Dissertation%2C+University+of+Pittsburgh.++++(Unpublished)++