Abstract: Dissolved and colloidal substance (DCS) accumulates gradually with the reduction of freshwater consumption in the pulp and paper industry. Too much DCS, which needs effective measures to deal with, harms the stability of paper machine operation and the quality of products. The aerobic and anaerobic biodegradability of water samples accumulated with DCS was comparatively researched through laboratory simulation. The results show that the aerobic disposal ratio of chemical oxygen demand (COD_Cr) from DCS can be increased 15.3% by adding nutrient substances. Aerobic biodegradation of lignin and its derivatives in DCS need co-metabolism substances. Therefore, engineering projects should add moderate nutrient substances to improve lignin's degradation. However, DCS was removed obviously by anaerobic microbes. The results of the experiment indicate that the removal percentage of DCS, COD_Cr and UV₂₈₀ are more than 40.5%, 55% and 68% respectively after one day, after which the degradation of DCS will be at a standstill, because the fatty acids with long chains and lignin polymers are syntrophism substrates, and their anaerobic biodegradation might be inhibited by the accumulation of acetic acid and hydrogen. Therefore, we should domesticate the anaerobic microbes and enhance the hydraulic retention time to increase their sustainable decomposition ability.