Construction Of Bacterial Agent For Kenaf Rettting And Wastewater Treatment，and Their Processes Exploration

Retting, which included water retting, chemical retting, biological retting,chemical-biological retting, is a very important process for obtaining kenaf fiber.However, these methods are only a settlement for retting problem. Without taking theenvironmental problems coursed pollutants and chemical residues into consideration. In thisstudy, the bacterial agent retting technology was established basing on thecomposition characteristics of kenaf bast, screening the strains which contain highenzyme activity. A_nd then the bacterial agent were prepared by biometricsmethod-Uniform Design. The bacterial agent process parameters were optimized.A_ndcharacteristics of the retting fibre were tested. Wastewater which from kenaf rettingwas treated by activated sludge process. The main results of this research were asfollows:1. Screening and identification of retting strainsThe twenty-four strains, which contain pectinase activity, xylanase activity,cellulase and lignin peroxidase, were screened from collected samples. By analyzingtheir enzyme activity, A₁and A₄was selected as the pectin enzyme produced strains,A₅and A₆were selected as xylanase produced strains, A₃and A₁0were selected ascellulose produced strains, E1and A₁4were selected as lignin peroxidase producedstrains. The eight bacteria strains were identified as bacillus through morphological,physiological and biochemical characteristics. Sequence analysis of16SrDNA_showed that A₁, A₃, A₄and A₁0were Paenibacillus, A₆and E1were Klebsiella, A₅was A_cinetobacter, A₁4was Enterobacter.2. Preparation of bacterial agent, optimization of retting conditionsThe combination of the bacterial agent was optimized by Uniform Design U8（88）.The residual gum content was considered as the only index to test the retting of everycombination. The best combination of the strains was A₁: A₄: A₁4: E1: A₅: A₆: A₃:A₁0=15:12:14:4:6:2:2:12. Through single factor experiments and orthogonal test, theoptimal kenaf retting parameters were as follows: retting temperature37℃, pH8.5, liquor ratio1:25, inoculation size20%, retting time48h. After retting in the optimalcondition, the residual gum rate was15.2%, and the fiber separability and flexibilitywere better.Using the optimized bacterial agent, the kenaf retting was carried on outdoorsunder the optimal retting conditions. Add the bacterial agent to kenaf solution whichpH was adjusted to8.5by limewater, and retted by aeration rate300ml/min. Theexperimental results showed that the kenaf retting could be finished in four days bythis retting method. Analysis of fibers indicated that its residual gum content was15.8%, feel, color and softness was superior to natural method.3. Retting wastewater by activated sludge processActivated sludge which collected from sewage treatment plant was acclimatedby gradually increasing the load method. After acclimating for a month, performanceof activated sludge including effluent chemical oxygen demand （COD） and activityhad improved, and maintained the influent COD between1000mg/L and1500mg/L.The effects of feeding mode, aeration time, aeration rate and settling time on theretting wastewater treatment were investigated. The optimal conditions were asfollows: batch water filling（two influent3h apart）, aeration time24h, aeration rate150ml/min, settling time120min. The quality indexes of the treated water wereeffluent COD289mg/L, pH7.66, color40, and fully meted national dischargestandard of sewage.