| Abstract:Anaerobic treatment of acid-precipitated black liquor was studied in an up-flow anaerobic sludge bed (UASB) reactor. The anaerobic biodegradability (BD) of the black liquor was tested. Changes of the removal efficiency of chemical oxygen demand (COD) and sulfate, the pH and oxidation reduction potential (ORP), methane production rate, contents of protein and polysaccharide in extracellular polymeric substances(EPS) of sludge, Zeta potential on the surface of the sludge and surface characteristics of sludge in different COD and sulfate volume loading conditions with investigated . Results showed that the anaerobic biodegradability of the black liquor was good and the BD was 85.07%.With the increase of influent organic loading rate, removal efficiency of COD rose first and fell afterwards, but sulfate removal rate kept increasing gradually. When CODCr organic loading rate was 2.00 kg/(m3·d), the CODCr removal rate came to the maximum value of 49%. When sulfate loading rate was 12.91 kg/(m3·d), the mean sulfate removal rate rose to about 42%. In the treatment process, pH fell gradually, ORP reduced to -430 mV slowly, methane production rate increased to 0.225 L/d at first and then decreased. The increase of COD loading of the influent contributed to higher content of protein and polysaccharide in EPS, lower Zeta potential on the surface of the sludge, and the surface of granular sludge surface became clean and dense. |
