Study on the Immobilization of Photosynthetic Bacteria (Rhodos Pirillaceae) for Wastewater Treatment
|Keywords||Immobilization Photosynthetic bacteria RhodosPirillaceae wastewater Optimize Oil Nitrogen removal Phosphorus removal Heavy metal|
In this paper,RhodosPirillaceae complex were identified to determine the dominant strains by using SEM electron microscope.The orthogonal experiment was designed to optimize medium for domesticating bacteria RhodosPirillaceae growth conditions and to determine ratio of the strains in RhodosPirillaceae complex.The morphological characteristics of four strains separated from RhodosPirillaceae complex were observed in the scanning electron microscopy（SEM）,it was found that Rp.palustris m-01 presented in the rosette-shaped morphology,Rp.capsulate m-02 in the chain-arranged morphology,Rp.sphaeroides m-03 in the spherical shape and Rm.Vannielii m-04 in lemon-shaped filaments.Bacteria growth rateμreached to 0.038 h-1 under the optimum conditions with inoculum of 8%and culture time of 54h based on the results from orthogonal experiment.Strains initial ratios for Rp.sphaeroides, Rp.palustris,Rp.capsulate and Rm.Vannielii in RhodosPirillaceae complex were percentage of 90.2:6.3:2.4:1.1,respectively.Effect of different composite carriers for RhodosPirillaceae complex on the immobilizing way,morphology,mechanical strength and stability of particles and optimal conditions for RhodosPirillaceae complex immobilization were investigated.The results show that, comparison with PVA and gelatin immobilized particles,the mechanical strength,toughness and permeability of the immobilized particles were increased by addition of zeolite according to comparison of three fixed-embedded materials properties within 10%PVA + 2%sodium alginate（CA）,2%sodium alginate + 1.5%gelatin,2%sodium alginate + 2%zeolite used for bacteria RhodosPirillaceae complex fixation.Degradation rate of ammonia-nitrogen in wastewater from Ming lake by immobilized RhodosPirillaceae complex attained 76.08%when the conditions for fixed strains were optimized as 2%CaCl2 solution saturated boric acid, temperature at 4℃for 24 h immobilization.Wastewater with high nitrogen-phosphorus origin from fish cultivation were treated by means of immobilized Rhodospirillum technique.Two different embedding materials were compared for the ammonia and phosphate removal effect of the immobilized RhodosPirillaceae. The process for removing ammonia and phosphate was optimized and the aquaculture water quality after the bioreactor for treatment was also analyzed.Through changing the conditions tests of immobilizing parameters,co-immobilization technique with zeolite and sodium alginate was determined,where the immobilizing gel was made from 2%zeolite,2%Na·Alg,which was much higher than the removal rate by free bacterium.Results of tests showed that the best operating condition was anaerobic light,4 mm grain diamete,1:5 of embedding proportion,5 g quantity of inoculation immobilization bacteria in every 1000 mL aquaculture wastewater. Experimental results revealed that RhodosPirillaceae immobilized in such a way are able to remove74.4%,84.26%,and 78.92%of ammonia,phosphate and CODMn in aquaculture wastewater after 4 day.In addition,through the long-term test,ammonia and phosphate were also largely removed by immobilized RhodosPirillaceae.This work is superiority for efficient treatment of aquaculture wastewater.Rp.sphaeroides was immobilized to treat high fatty acid-rich food oily wastewater.Three different embedding materials were compared for the oil removal effect of the immobilized Rp.sphaeroides.The process for removing oil was optimized and the degradation of fatty acids in oily wastewater was also analyzed.The gel complex with 2%zeolite and 2%sodium alginate was selected after comparison for co-immobilization,with a diameter of 4 mm of the immobilized granule and an embedding ratio of 1:2.After 6 days treatment with 10 g·L-1 granules under aerobic conditions in the darkness,the oil,NH4+-N,and PO43- in the wastewater were removed by 80.1%,87.4%and 96.3%.The amount of oil removed by immobilized PSBRS was 50%higher than that by the same bacteria without immobilization.Fatty acids were also largely removed by immobilized Rp.sphaeroides.This work is beneficial to the screening and immobilization of microorganisms for efficient treatment of oily wastewater.Wastewater containing cadmium（Cd）,chromium（Cr） were investigated by means of immobilized photosynthetic bacteria Rp.sphaeroides technique.Gel complex with 2%of Zeolite and 2%of sodium alginate（CA） were determined within four kinds of different embedding materials for photosynthetic bacteria Rp.sphaeroides immobilization after comparisons of removal efficacy of heavy metals（Cd,Cr） in wastewater.It is found that removal efficacy of heavy metals（Cd,Cr） treated by immobilized Rp.sphaeroides technique was higher than processing by free bacteria suspension.The technological conditions for processing wastewater containing heavy metals（Cd,Cr） with immobilized photosynthetic bacteria were also optimized.The experimental results showed that heavy metals could be efficiently accumulated by the immobilized bacteria with removal efficiencies of 96.7%for wastewater containing 40 mg·L-1 Cd at optimal pH 6 and adding strain dose of 15 g·L-1 Immobilized bacteria regeneration studies were carried out over four sorption-desorption cycles. Removal efficiencies of Cd in 51.2%for wastewater with concentration of 40 mg·L-1 Cd was still attained in the third cycle.In the bioreactor,immobilized Rp.sphaeroides technique was used to treated industrial electroplating wastewater for 3 h.Removal efficiencies of Cd in 98.8%and other concentrations of heavy metals in 90.0%were achieved,respectively.