Izicishamlilo zisebenzisa igwebu le-Film-forming (AFFF) elimanzi ukuze lisize ukucisha imililo okunzima ukulwa nayo, ikakhulukazi imililo ehlanganisa uphethiloli noma olunye uketshezi oluvuthayo ‚ olwaziwa ngokuthi imililo ye-Class B. Kodwa-ke, akuwona wonke amagwebu okucisha umlilo ahlukaniswa njenge-AFFF.

Amanye amafomu e-AFFF aqukethe ikilasi lamakhemikhali aziwa ngokuthii-perfluorochemicals (PFCs)futhi lokhu kuphakamise ukukhathazeka mayelana nokwenzekaukungcoliswa kwamanzi angaphansi komhlabaimithombo evela ekusetshenzisweni kwama-ejenti e-AFFF aqukethe ama-PFC.

Ngo-May 2000, i-3M Inkampaniithe ngeke isakhiqiza i-PFOS (perfluorooctanesulphonate)-based flurosurfactants isebenzisa inqubo ye-electrochemical flouorination. Ngaphambi kwalokhu, ama-PFC ajwayelekile asetshenziswa kumagwebu okucisha umlilo kwakuyi-PFOS kanye nokuphuma kwayo.

I-AFFF iwucisha ngokushesha umlilo kaphethiloli, kodwa iqukethe i-PFAS, emele izinto ze-per- kanye ne-polyfluoroalkyl. Okunye ukungcola kwePFAS kuvela ekusetshenzisweni kwamagwebu okucisha umlilo. (Isithombe/Isizinda Esihlanganyelwe sase-San Antonio)

IZIHLOKO EZIHLOBANE

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Phakathi neminyaka embalwa edlule, imboni yegwebu elicisha umlilo iye yasuka kuPFOS kanye nokuphuma kwayo ngenxa yengcindezi yomthetho. Labo bakhiqizi baye bathuthukisa futhi balethe emakethe amagwebu okucisha umlilo angasebenzisi amakhemikhali e-fluoro, okungukuthi, angenayo i-fluorine.

Abakhiqizi bamagwebu angenayo i-fluorine bathi lawa magwebu anomthelela omncane endaweni ezungezile futhi ahlangabezana nezimvume zamazwe ngamazwe zezidingo zokucisha umlilo kanye nokulindelwe ngabasebenzisi bokugcina. Noma kunjalo, kuyaqhubeka nokukhathazeka kwemvelo mayelana namagwebu okucisha umlilo futhi ucwaningo ngale ndaba luyaqhubeka.

UKHATHAZEKA NGOKUSETSHENZISWA KWE-AFFF?

Ukukhathazeka kugxile kumthelela omubi ongaba khona endaweni ezungezile kusukela ekukhishweni kwezixazululo zegwebu (inhlanganisela yamanzi nokugxila kwegwebu). Izinkinga eziyinhloko ubuthi, ukubola kwezinto eziphilayo, ukuphikelela, ukulapheka ezikhungweni zokuhlanza amanzi angcolile kanye nokulayishwa kwezakhi zomhlabathi. Konke lokhu kuyimbangela yokukhathazeka lapho izixazululo zegwebu zifinyelelaizinhlelo zamanzi zemvelo noma zasekhaya.

Lapho i-PFC equkethe i-AFFF isetshenziswa ngokuphindaphindiwe endaweni eyodwa isikhathi eside, ama-PFC angasuka egwebu angene emhlabathini bese engena emanzini angaphansi komhlaba. Inani le-PFC elingena emanzini angaphansi komhlaba lincike ohlotsheni kanye nenani le-AFFF esetshenzisiwe, lapho isetshenziswe khona, uhlobo lwenhlabathi nezinye izici.

Uma imithombo yangasese noma yomphakathi itholakala eduze, ingase ithintwe ama-PFC asendaweni lapho i-AFFF yayisetshenziswa khona. Nakhu okushicilelwe uMnyango Wezempilo waseMinnesota; ingesinye sezifundazwe ezininganaukuhlola ukungcola.

"Ngo-2008-2011, i-Minnesota Pollution Control Agency (MPCA) yahlola inhlabathi, amanzi angaphezulu, amanzi angaphansi komhlaba, kanye nezinsalela ezindaweni ezingu-13 ze-AFFF ezizungeze isifunda. Bathole amazinga aphezulu e-PFC kwezinye zezindawo, kodwa ezimweni eziningi ukungcola akuzange kuthinte indawo enkulu noma kube yingozi kubantu noma endaweni ezungezile. Iziza ezintathu - i-Duluth Air National Guard Base, i-Bemidji Airport, kanye ne-Western Area Fire Training Academy - zihlonzwe lapho ama-PFC ayesakazeke ngokwanele kangangokuthi uMnyango Wezempilo waseMinnesota kanye ne-MPCA banquma ukuhlola imithombo yokuhlala eseduze.

“Lokhu kungenzeka kakhulu eduze nezindawo lapho i-PFC equkethe i-AFFF isetshenziswe kaningi, njengezindawo zokuqeqesha umlilo, izikhumulo zezindiza, izindawo zokuhluza kanye nezitshalo zamakhemikhali. Mancane amathuba okuthi kwenzeke kusukela ekusetshenzisweni kanye kwe-AFFF ukulwa nomlilo, ngaphandle uma kusetshenziswa imiqulu emikhulu ye-AFFF. Nakuba ezinye izicishamlilo eziphathwayo zingasebenzisa i-PFC-equkethe i-AFFF, ngesinye isikhathi ukusetshenziswa kwenani elincane kangako ngeke kube yingozi emanzini angaphansi komhlaba.”

KUCHITHWA Igwebu

Ukukhishwa kwesisombululo segwebu/amanzi kungenzeka kube umphumela wesimo esisodwa noma ngaphezulu kwezilandelayo:

• Ukucima umlilo ngesandla noma imisebenzi yokuvala uphethiloli;
• Ukuqeqeshwa kokuzivocavoca lapho kusetshenziswa igwebu kuzimo;
• Uhlelo lwemishini yegwebu kanye nokuhlolwa kwemoto; noma
• Ukukhishwa kwesistimu elungisiwe.

Izindawo lapho kungenzeka khona umcimbi owodwa noma eminingi ihlanganisa izindawo zezindiza kanye nezindawo zokuqeqesha izicishamlilo. Izinsiza eziyisipesheli eziyingozi, njengezindawo zokugcina impahla ezivuthayo/eziyingozi, inqwaba yezindawo zokugcina uketshezi oluvuthayo kanye nezindawo zokugcina imfucuza eyingozi, nazo zenza uhlu.

Kuyinto efiselekayo kakhulu ukuqoqa izixazululo zegwebu ngemva kokusetshenziswa kwazo emisebenzini yokucima umlilo. Ngaphandle kwengxenye yegwebu ngokwayo, igwebu kungenzeka lingcoliswe uphethiloli noma izinto zokubasa ezibandakanyeka emlilweni. Umcimbi ojwayelekile wezinto eziyingozi usuqhamukile.

Amasu okubamba mathupha asetshenziselwa ukuchithwa okubandakanya uketshezi oluyingozi kufanele asetshenziswe uma izimo nabasebenzi zivuma. Lokhu kufaka phakathi ukuvimba amadreyini eziphepho ukuvimbela igwebu/isixazululo samanzi esingcolile ukuthi singangeni ohlelweni lwamanzi angcolile noma imvelo ingahloliwe.

Amaqhinga okuzivikela afana nokudala amadamu, ukucwiliswa emanzini kanye nokuphambukisa kufanele kusetshenziswe ukuze kuthathwe isisombululo segwebu/amanzi siyiswe endaweni efanelekile ukubamba kuze kube yilapho sikhishwa usonkontileka ohlanza izinto eziyingozi.

UKUQEQESHWA NGEgwebu

Kunamagwebu okuqeqesha aklanywe ngokukhethekile atholakala kubakhiqizi abaningi begwebu abalingisa i-AFFF ngesikhathi sokuqeqeshwa okubukhoma, kodwa angaqukathi ama-floufolosurfactants afana ne-PFC. Lawa magwebu okuqeqeshwa ajwayele ukubola futhi anomthelela omncane kwezemvelo; angaphinda athunyelwe ngokuphepha endaweni yokuhlanza amanzi angcolile ukuze acutshungulwe.

Ukungabi bikho kwama-fluosurfactants ekuqeqesheni igwebu kusho ukuthi lawo magwebu anokuncipha kokumelana nokushiswa emuva. Isibonelo, igwebu lokuqeqesha lizohlinzeka ngokuvimbela umhwamuko wokuqala emlilweni woketshezi oluvuthayo okuholela ekucimeni, kodwa leyo ngubo yegwebu izophuka ngokushesha.

Lokho kuyinto enhle ngokombono womfundisi njengoba kusho ukuthi ungaqhuba ezinye izimo zokuqeqesha ngoba wena nabafundi bakho anilindi isifanisi sokuqeqesha ukuthi sishise futhi silunge.

Ukuzivocavoca umzimba, ikakhulukazi labo abasebenzisa igwebu langempela eliqediwe, kufanele kufake izinhlinzeko zokuqoqwa kwegwebu elisetshenzisiwe. Okungenani, izikhungo zokuqeqesha umlilo kufanele zibe nekhono lokuqoqa isisombululo se-foam esisetshenziswa ezimweni zokuqeqesha zokukhishwa endaweni yokuhlanza amanzi angcolile.

Ngaphambi kwalokho kukhishwa, indawo yokuhlanza amanzi angcolile kufanele yaziswe futhi imvume inikezwe umnyango wezomlilo ukuze i-ejenti ikhishwe ngenani elinqunyiwe.

Impela ukuthuthukiswa kwezinhlelo zokungeniswa kwegwebu Lekilasi A (futhi mhlawumbe nekhemistri ye-ejenti) kuzoqhubeka njengokuthuthuka njengoba kwenzekile kule minyaka eyishumi edlule. Kepha mayelana nokugxilwa kwegwebu le-Class B, imizamo yokuthuthukisa ikhemikhali ye-ejenti ibonakala iqandisiwe ngesikhathi ngokuthembela kubuchwepheshe obukhona obukhona.

Selokhu kwethulwa imithethonqubo yezemvelo phakathi neminyaka eyishumi edlule noma kanjalo kuma-AFFF asekelwe ku-fluorine lapho abakhiqizi begwebu lezicishamlilo beyithathele phezulu inselele yentuthuko. Eminye yale mikhiqizo engenayo i-fluorine ingeyesizukulwane sokuqala kanti eminye isizukulwane sesibili noma sesithathu.

Bazoqhubeka nokuguquka kokubili kwamakhemikhali e-ejenti nokusebenza komlilo ngenhloso yokufeza ukusebenza okuphezulu oketshezini oluvuthayo nokuvutha, ukuthuthukiswa kokumelana nokushisa okuthuthukisiwe kokuphepha komlilo kanye nokuhlinzeka iminyaka eminingi eyengeziwe yokuphila kweshalofu phezu kwamagwebu atholakala kumaprotheni.