Method for comprehensive treatment of wastewater and sludge gas utilization of cane sugar factory

The invention discloses a method for treating cane sugar factory wastewater comprehensively and using methane, which comprises the following steps: removing fibers and depositing coarse dregs in pretreated bagasse spray water, bagasse washing water, lime sludge filtered water, part of cooling water, papermaking alkaline wastewater, alkali reclaiming vaporization condensation water, and part of paper machine wastewater after reclaiming white slime of a cane sugar factory; mixing and properly heating all the water and delivering the mixture into an anaerobic reactor to perform anaerobic reaction; desulfurizing, decarburizing, purifying, filtering and compressing the obtained methane, and using the methane for heating a paper machine; and performing aerobic biochemical treatment on the sewage generated by the reaction in the anaerobic reactor so that the sewage reaches the discharge standard and is discharged, wherein sludge can be applied to preparing an organic compound fertilizer. The method can treat the sewage of the cane sugar factory comprehensively, can reclaim part of energy generated in the process of the wastewater treatment and apply the energy to production, thereby greatly reducing the production cost and bringing about better economic benefits and social benefits.