The effects of temperature and pH bacterial degradation of latex paint in humid environment

Abstract

The goal of this study was to integrate the activities of paint deterioration of microbial communities (microcosms) on the basis of environmental factors. The effect of temperature and pH on bacterial degradation of latex paint under humid condition by bacterial isolates was studied. Results obtained revealed that paint industrial waste (PIW) and paint film scrap (PFS) contained approximately 28.2% to 37.3% of dry organic content (DOC), pH 6.6 to 8.3, optical density (OD) 2.5 to 3.9 and undetermined amount of Ca²⁺, Na⁺, K⁺, SO₄ ^2- and NO₃^-. Thirteen (13) isolates were obtained from PIW and fifty two (52) from PFS. The main heterotrophic count ranged from 8.7 to 9.4 × 10⁸ cfuml^-1 for PIW and 3.4 to 6.8 × 10⁶ cfuml^-1 for PFS. The bacterial genera and their percentage occurance for PIW and PFS were: Pseudomonas (40:32%), Bacillus (26:44%), Norcadia (9:6%), Streptomyces (0:6%), Alcaligenes (11:3%), Micrococcus (14:7%) and Flavobacterium (0:27%) respectively. The organisms exhibited various degree of paint degradation under different temperature and pH points. Pseudomonas demonstrated the highest rate of degradation at pH 7.4 and the lowest at pH 4.2. Bacillus had its highest rate at pH 6.3 and lowest at pH 3.5 while that of Micrococcus occurred at pH 4.2 and 8.1 respectively. Equally, Pseudomonas and Bacillus had double peaks of degradation at 28^oc and 40^oc while that of Micrococcus occurred only at 40^oc. However, 28^oc and 40^oc are considered optimal and maximal temperature for biodegradation of paint. Also, the effect of pH and temperature was independent and insignificance at P < 0.05. The study therefore, indicated that paint and painted surfaces (objects) can be preserved from bacterial contamination, deterioration and degradation by controlling the storing pH and temperature.

KEYWORDS: Paint, temperature, pH, biodegradation, significance.