Hydrolysis - A Good Oxide Handling Of Paper Mill Wastewater Process

The characteristics of paper industry and problems of paper making wastewater treatment are presented in this paper. In order to decrease both investment and operating expenses, the feasibility to treat the alkali straw pulp making intermediate wastewater by biological hydrolysis (acidification) and sequencing batch reactor (SBR) is studied using laboratory-scale reactor. The results show that the stirrers and biological carriers are needed in the reactor of biological hydrolysis when the wastewater is pretreated. Also, Hydraulic retention time (HRT) is beyond 10 hours. The biodegradability and insoluble chemical oxygen carbon (COD) of the wastewater are enhanced to some extent after biological hydrolysis. Thus, sedimentation unit is followed for removing suspended solid in the wastewater. In the system of SBR following biological hydrolysis reactor, the aeration period should exceed 6.5 hours. The wastewater is treated directly by SBR system without pretreatment on condition that the COD of the feed is less than 1,000 mg/l. It should be emphasized that SBR reactor must be followed by useful separation process, such as filtration, coagulant sedimentation and so on. The effluent from SBR system does not meet the requirement of discharge standard as the temperature is below 10C,.The same treatment efficiency are achieved using two different aeration methods in SBR operation, such as the restrained aeration and the unrestrained aeration The idle period of SBR system does not affect the removal efficiency. The value of oxidation-reduction potential (ORP) can be employed to reflect the endpoint of aeration period of SBR system in engineering design. The endpoint characteristic of the aeration period in SBR system is that the value of ORP rises sharply and fluctuates between 30mv and 50mv subsequently.