Flax Retting Wastewater Treatment Process Pilot Study

Flax retting is used to adopting retting technique, and this will waste much of water. Waste water of retting flax can be divided one time retting water and two times retting water, these two kind of waste water were emitted at different time, and elements of these two kind of water is different greatly. If it was not be treated or emitted directly by preliminary treatment, it would serious polluted the local water and caused waste of water resources.We analyzed the process of flax retting project, point out the treatment method of organized step by step and recycling usage of waste water to retting waste water. We combined treatment project and production project, achieved the change of final management to control of pollution process. Recycling usage of waste water, usage of methane that produced by anaerobic treatment, improving reviving efficiency of water resources, reducing amount of pollution, and these would achieved cleaner production in flax industry. We studied the recycling usage of the second waste water that treated by mix ion-air flotation-UASB ethnics to retting flax in this paper, specific studied the technical problem of UASB and retting water index, and designed technological processes that agreed with actual condition according to the motion of UASB. Experiment results as follows: the COD consistency of second retting water was 6000 to 7100mg/L, but the COD consistency could reach 1779.50—2198.3 mg/L after consumption by anaerobic microbe in UASB. The remove rate of COD can achieve 66% or more, and water affluently was stable. Retting water which was treated was used to retting again, when COD was about 2000mg/L, the retting time of flax is 90 hours, which matched to natural retting time. When COD is 1000mg/L to 1500mg/L,the retting time is 80, and it was 10 hours shorter than natural retting. But COD was 2500mg/L, the retting time was about 128 hours, which indicated that recycling water could accelerate the retting time when COD waswithin 2000mg/L. the anaerobic methane output of retting water was 52.3% to 74% compared to theory output which removing lkgCOD could produce 0.34～0.38m~3 of methane. And methane content was about 58.8% to 66.7%, indicated that it was rich of methane resource.