Effect of Sewage Sludge Alkalization and Acidification on Keratinolytic and Keratinophilic Fungi
نویسنده
چکیده
This study aimed to determine the influence of sewage sludge alkalization and acidification on the qualitative and quantitative composition of keratinolytic and keratinophilic fungi in a model experiment. The sludge was alkalized to pH 9 with 0.5N NaOH, 0.5N KOH, 0.5N NH 4 OH or with 2% burnt lime mixed with powdered limestone (20g CaO + 5g CaCO 3 ), and acidified to pH 4 with 0.5N HCl, 0.5N HNO 3 or 0.5N H 2 SO 4 . The sludge with unmodified pH (6.5) served as control. The hair baiting method with four incubation temperatures (23, 29, 33, and 37°C) was used to examine fungi. The sludge alkalization with KOH, NaOH or CaO+CaCO 3 increased the number of keratinolytic fungi but decreased the number of keratinophilic fungi. The inhibition of the growth of keratinolytic fungi was observed due to the sludge acidification with H 2 SO 4 or HCl. The sludge acidification with HNO 3 or HCl stimulated keratinophilic fungi to grow. Sludge acidification with HNO 3 eliminated keratinolytic fungi, while acidification with H 2 SO 4 eliminated keratinophilic fungi. Results are discussed from ecological and epidemiological points
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