Using Activated-Carbon Column for Treating Dyeing Wastewater

[[abstract]]現今染整廠逐漸走向數量少、式樣多、且多數合纖染色，其所用染助劑偏多元且生物降解效率偏低。如加上節水及空間限制，常導致廢水強度增加，使活性污泥法負荷加重，效率變低。本計畫配合某染整廢水處理場亦有類似問題。目前該廢水場進流化學需氧量(ChemicalOxygenDemand,COD)約2,500mg/L，經生物及混凝沉降後，出流COD約在200mg/L左右，常無法達到法規值140mg/L的要求，而需其它處理手段。本研究以空白及控制等兩管柱模槽，測試實場廢水COD去除效率，並尋求可行處理操作條件，以解決活性污泥池負荷過重，或出流超標等問題。故本論文研究目的包括:(1)確認活性碳(Activecarbon,AC)吸附管柱操作因子及操作條件、(2)決定管柱活性碳最適再生工法、及(3)測試管柱在實場處理進出流水COD吸附效率等。研究初期將首先監測廢水場主要單元COD去除效率，並探討吸附及再生技術。實驗結果首先確認模槽管柱處理進出流水活性碳量分為2,800及1,400克，流速定為120mL/min。如以袋裝(40克-活性碳/袋)方式填充管柱，則活性碳吸附量僅為無袋裝填充管柱的一半，具推論應是袋裝易產生短流現象所導致。另管柱在處理進流COD(~2,500mg/L)時，可維持近50%COD去除約4小時;在處理出流COD(~185mg/L)時，約可維持處理效果在140mg/L以下約50小時。而在懸浮固體移除效率上，管柱處理懸浮固體去除效率約為88%及50%。再生實驗顯示，以初始雙氧水濃度5.6%及EDTA-Fe濃度4mM，反應一小時，是可行再生操作模式。經再生後，活性碳吸附量可保持較長久穩定;但如以水再生活性碳，則活性碳較原吸附量下降33%，並將快速飽和而無法再吸附COD。最後，經評估單位活性碳吸附量、所需槽體體積、及處理所需活性碳及藥劑成本等因素可知，以管柱活性碳處理該廠廢水出流相對可行。目前已選定一座兩噸管柱進行安裝及測試。[[abstract]]ThetrendofcurrentdyeingindustryinTaiwantendstobemorediverseonproductsanddyemostlytheartificialfibers.Bydoingso,theuseofdyesandtheirauxiliarychemicalsalsovaryandhavelowbiodegradabilityinnature.Theproblemcomplicatedwiththewater-savingmovementandthelimitofspaceinplantleadstotheincreaseofwastewaterstrengthandoftenoverloadstheactivatedsludgeprocess.Thecompanyworkedwiththisstudyencountersasimilarproblemasmentionedabove.CurrentlytheinfluetCODoftheplantwasabout2,500mg/L.Followedbyactivatedsludgeandcoagulationprocess,theplanteffluentCODwasabout185mg/L,whichtakesanothertreatmentalternative,oftenoxidativemean,tomeettheregulatorystandardof140mg/L.Inthisstudywefocusedontheuseoftwopilotactivatedcarbon-(AC-)filledcolumnstotreattheplantinfluentandeffluentseparativelyinordertoresolvethesituationsofAStankoverloadand/ortheexceedofeffluentregulatorylimits.Thus,thepurposeofthisstudyincluded:(1)toconfirmedtheoperationalfactorsandtheiroperatingconditionsofthetwopilotcolumns,(2)todeterminethemostapplicablemeaninACregeneration,and(3)toexaminetheefficienciesoftreatingtheinfluentandeffluentCODinplant.Atfirst,along-termmonitoringofthemainunitsperformanceofthewastewaterplantwasconducted,andtheadsorptionandregenerationofACwasstudied.CODanalysiswasdonebydichromateoxidationfollowedbyaUVspectrophotometerforquantification.Theresultsindicatedthattheflowrateofthepilotcolumnwasfixedat120mL/min,andtheamountsofACusedintreatinginfluentandeffluentwastewaterwere2,800and1,400,respectively.IfthecolumnfilledwithACbagsthatcontained40gramsofACeach,itsadsorptioncapacitywasonlyanhalfoftheACun-bagged.ItappearedthatbaggingtheACresultedintheshort-circulationoftheflowandreducedtheadsorptionefficiency.WhenthepilotcolumnwasusedtoadsorbtheinfluentCOD,a50%CODremovallastedfor4hours;yetiftreatingtheeffluent,thecolumneffluentmaintainedbelow140mg/Lformorethan50hours.Intermsofsuspendedsolidsremoval,about88and50%ofSSwereremovedwhentreatingtheplantinfluentandeffluent,repectively.Moreover,theresultsofregenerationtestsshowedthattheuseof5.55%peroxideand4mMofEDTA-FeandreactingforonehourwassufficientforACregeneration.Regenrationinsuchmanner,theACadsorptioncapacityshowedmaintainingatstablevalues,yetifregeneratedbyonlywater,theACadosorptioncapacitydroppednearly33%andwouldhavebeenrapidsaturatedandloseitsfunctionshortly.AfterevaluationonspecificACadsorptioncapacity,thenessarytankvolume,andtheneededamountofACandregagentcosts,theuseoftheACcolumntotreatplanteffluentisratherfeasible.Atwo-toncolumnissetupandgoingtobeoperatedtoverifytheresultsinlargescale