Biotransformation kinetics of benzalkonium chlorides by Pseudomonas sp. BIOMIG1 under different conditions

Active ingredients of disinfectants are very common pollutants in urban and industrial wastewater. Removal of these contaminants is very difficult in biological treatment systems. As a result; these pollutants, which are also frequently detected in surface waters, threaten both nature and human health. The objective of this study is to determine the optimum conditions that will provide the most efficient removal of benzalkonium chlorides (BACs), one of the most common contaminants in wastewater, in biological treatment systems. For this purpose, BAC biotransformation kinetics were determined under different conditions using Pseudomanas sp. BIOMIG1, a bacterium that is the key BAC degrader in the environment. Using the data collected and the Michaelis-Menten growth model, BAC biotransformation kinetic parameters were calculated and the effect of the applied conditions on kinetics was determined. BIOMIG1 can transform BACs at a rate of 1.4 mg/L-hour and converts these pollutants into ammonia and carbon dioxide. BAC mineralization can be achieved even at low bacterial densities such as 105 cells/mL after a short delay. When biotransformation rate of BAC homologs was compared, BAC with 14 carbon alkyl chain length had the fastest and BAC with 16 carbons had the slowest rate of biotransformation. The temperature at which the BAC biotransformation rate was the highest was 35 oC.. BAC was converted to benzyldimethylamine which was accumulated in the medium or was not transformed at all at temperatures above 35 oC since BIOMIG1 does not survive above this temperature. The outcomes presented in this study would be used for the design and operation of advanced treatment systems targetting the removal of micropollutants like BACs.

Benzalkonyum klorürlerin Pseudomonas sp. BIOMIG1 tarafýndan farklý koþullar altýnda biyotransformasyon kinetiði

Dezenfektan aktif maddeleri kentsel ve endüstriyel atýksularda oldukça sýk rastlanan kirleticilerdir. Bu kirleticilerin biyolojik sistemlerde giderimi oldukça zordur. Yüzeysel sularda da sýkça karþýlaþýlan bu kirleticiler hem doðal hayatý hem de insan saðlýðýný tehdit etmektedir. Bu çalýþmanýn amacý, atýksuda en çok karþýlaþýlan kirleticilerden biri olan benzalkonyum klorürlerin (BAK’lar) biyolojik sistemlerde en verimli þekilde giderimini saðlayacak koþullarýn belirlenmesidir. Bu amaçla, atýksudan izole edilmiþ BAK gideren bir bakteri olan Pseudomanas sp. BIOMIG1’in farklý koþullarda BAK biyotransformasyon kinetiði belirlenmiþtir. Elde edilen veriler ve Michaelis-Menten modeli kullanýlarak, bu mikroorganizmanýn BAK biotransformasyon kinetiði parametreleri hesaplanmýþ ve uygulanan koþullarýn kinetiðe etkisi belirlenmiþtir. BIOMIG1, BAK’larý 1.4 mg/L-saat hýzýnda giderebilmekte ve bu kirleticileri amonyak ve karbon dioksite dönüþtürmektedir. 105 adet/mL bakteri yoðunluðu gibi düþük bakteri yoðunluklarýnda bile BAK gecikmeli de olsa yüksek hýzda giderilebilmektedir. BAK homologlarýnýn biyotransformasyon hýzý karþýlaþtýrýldýðýnda, 14 karbon alkil zincir uzunluðuna sahip BAK en hýzlý, 16 karbonlu BAK ise en yavaþ biyotransformasyon hýzýna sahiptir. BAK giderim hýzýnýn en yüksek olduðu sýcaklýk 35 oC’dir, bu sýcaklýk üstündeki sýcaklýklarda BIOMIG1 yaþayamamaktadýr. Dolayýsýyla yüksek sýcaklýklarda BAK parçalanmasý ya benzildimetilamin birikmesiyle sonlanmýþ ya da hiç gerçekleþmemiþtir. Bu çalýþmanýn sonuçlarý, özellikle BAK gibi mikrokirleticilerin arýtýmýný hedefleyen ileri arýtma sistemlerinin tasarlanmasý ve iþletilmesinde faydalý olacaktýr.