Removal Of Inorganic Nitrogen And Phosphorus From Mariculture Wastewater By Photosynthetic Bacteria

With the rapid development of mariculture,the treatment of mariculture wastewater is a huge problem.Photosynthetic bacteria(PSB)can use organic material under dark oxygen and light anaerobic conditions,and can be widely used in wastewater treatment.At the same time,photosynthetic bacteria are rich in active substances such as proteins and photosynthetic pigments.So they have a dual advantage which includes mariculture wastewater treatment and bioactive substance recycle in the treatment of non-toxic wastewater,making them more competitive.The effects of different initial pH values conditions of 7.0,7.5,8.0,8.5,9.0,9.5 and 10.0 on the removal efficiencies of ammonia nitrogen,phosphorus and COD by the photosynthetic bacteria in mariculture wastewater are studied.The amount of pigments accumulation and stability are analyzed.The effects of different initial pH values on the nitrogen and phosphorus removal ability of Ectothiorhodospira shaposhnikovii strain P2 are studied.Results show that P2 has strong alkaline resistance ability.The ammonia nitrogen,phosphorus,and COD removal abilities and cell biomass and pigments accumulation under alkaline conditions are significantly higher than those under neutral conditions.At the pH value of 8.0,strain P2 has the highest wastewater treatment ability,biomass(OD660nm.1.9791 ±0.0023)and pigments accumulation.The ammonia nitrogen removal,phosphorus removal,and COD removal are 273.94 ± 2.62 mg/L,20.80 ± 2.84 mg/L,and 2320.00± 20.00 mg/L,respectively.The effects of different NaCl concentrations on the wastewater treatment by strain P2 are studied.Under the condition of 20 g/LNaCl concentration,the strain P2 acquires the highest biomass(OD660nm=1.7128 ± 0.1100),ammonia nitrogen,phosphorus,COD and sulfate removal(244.33 ± 1.51,40.31 ± 0.55,1810.62± 76.64 and 757.53±15.66 mg/L,respectively).Under the condition of 20 g/L NaCl concentration,the accumulation of carotenoids and bacteriochlorophyll a are also the highest.The influence of different inoculation rates on wastewater treatment by strain P2 are studied.The cells growth of strain P2 have no significant differences when inoculation ratio ranges from 10?20%(vbacterial liquid volume/Vwastewater volume),and the strain P2 acquires the highest biomass(OD660nm=0.0666?0.1350).Under ratios 10?20%,The ammonia nitrogen,phosphorus,COD and sulfate removal are 245?253 mg/L,24?30mg/L,920?987 mg/L and 600?647 mg/L,respectively.Under the condition of 10?20%inoculation rates,the accumulation concentrations of carotenoids and bacteriochlorophyll a are also higher than the condition of 5%inoculation rate.The effects of different conditions,including temperature,pH value and the concentration of sodium bicarbonate and sodium benzoate on the stability of carotenoids and bacteriochlorophyll a within 24 h,are studied.At 60 0C,the preservation rate of carotenoids is 133.33 ± 0.58%.At 4?,the preservation rate of bacteriochlorophyll a is 91.89± 0.45%.At pH value of 11.47,the preservation rates of carotenoids and bacteriochlorophyll a are 100.67 ± 0.14%and 91.91±0.03%,respectively.The concentration of 0.0 and 1.5 g/kg sodium bicarbonate and low concentration of sodium benzoate have less effect on carotenoids.The concentration of 0.0 and 2.0 g/kg sodium bicarbonate and the concentration of 0.0 and 1.5 g/kg sodium benzoate have less effect on bacteriochlorophyll a.