Resistance capability of microaerobic granular sludge for pentachlorophenol (PCP) degradation subjected to pH shock

Abstract

The resistance capability to pH shock of microaerobic granular sludge for pentachlorophenol (PCP) degradation was studied. The results show that it had little effect on the system under short-term shock, and the system returned to normal state immediately，while large adverse effect occurred under long-term shock, and the system required long time to recover. The content of extracellular polymers (ECPs) including proteins (PN) and polysaccharides (PS) decreased significantly, as well as the ratio of proteins and polysaccharides for 8 days pH shock, and there was an increase in sludge volumetric index (SVI) values of sludge and a decrease in settling velocity. Compared with the normal pH, it was found that the number of bacillus in microorganisms reduced for pH shock, and recession-type cells occurred by being observed with scanning electron microscope, especially at pH 6.0 and 9.0 there was a more serious decline in the treatment effect and deterioration in the physicochemical properties of granular sludge.

Key words: Resistance capability, microaerobic granular sludge, pentachlorophenol (PCP), pH shock.