微生物固定化生物炭对水体铵态氮去除效果的研究

为探究微生物固定化生物炭对水体铵态氮(NH_4~+-N)去除效果的影响,以花生壳生物炭(BC)为载体,通过吸附和包埋两种方法将脱氮副球菌(Paracoccus denitrificans)、假单胞菌(Pseudomonas)和拉乌尔菌(Raoultella)固定在生物炭上,然后将该微生物固定化生物炭投加到NH_4~+-N模拟废水中,结合表面微观结构表征,研究其对水体NH_4~+-N的去除性能。结果表明:吸附和包埋法均能将微生物固定到生物炭表面,并在生物炭表面呈饼状、杆状和粒状分布。吸附法固定脱氮副球菌和假单胞菌,分别缩小生物炭比表面积和孔容积5.5%～17.2%和5.4%～25.8%。吸附法固定拉乌尔菌,分别增大生物炭比表面积和微孔容积45%和43%,缩小介孔和大孔容积。包埋法引入—CH_2、C—H和C=O键等新的官能团,但由于带入包埋材料,使固定微生物生物炭比表面积减少87.3%～96.3%,孔容急剧缩小,其中介孔缩小84.1%～98.2%,微孔几乎全部被封堵。因此,吸附法制得的固定化微生物生物炭对水体NH_4~+-N去除速率较包埋法高1.16～3.44倍。研究表明,吸附法和包埋法均能将微生物固定在生物炭表面,包埋法对生物炭的孔隙结构和表面官能团影响更大,吸附法对水中NH_4~+-N的去除效率更高。

Synthesis of microbial immobilized biochar for the removal of ammonia nitrogen from aqueous solutions

To explore the effects of immobilized microbial biochar on the removal of ammonium nitrogen(NH₄⁺-N) in water, a comparative experiment was conducted. Paracoccus denitrificans(T), Pseudomonas(J), and Raoultella(L) were immobilized on peanut shell biochar (BC) through adsorption and embedding methods. After adding the three microorganisms and their immobilized biochars into waste water containing ammonia nitrogen, the performance of these treatments on NH₄⁺-N removal were assessed, as well as surface structure, functional groups, and pore structure parameters were evaluated. The results showed that both adsorption and embedding methods immobilized microorganisms on the surface of biochar as evident from the distribution of round, rod, and granular forms. The specific surface area and pore volume of immobilized Paracoccus denitrificans and Pseudomonas biochar reduced by 5.5%~17.2% and 5.4%~25.8% by the adsorption method, respectively. Regarding immobilized Raoultella biochar by adsorption, the specific surface area and micropore volume of biochar increased by 45% and 43% times, respectively, and the mesoporous and macroporous volumes also reduced. Although new functional groups, such as -CH₂, C-H, and C=O bonds, were introduced via embedding, the specific surface area of embedded microorganisms on biochar reduced rapidly by 87.3%~96.3% in comparison with that of biochar and adsorbed microorganisms biochars. Moreover, the mesoporous pore volume decreased 84.1%~98.2% and the micropores were almost completely blocked by the embedded materials, such as polyvinyl alcohol hydrogel(PAH) and sodium alginate(SA). Therefore, the NH₄⁺-N removal rate of immobilized microbial biochar prepared by the adsorption method was 1.16~3.44 times higher than that of the embedding method. Our results indicated that both adsorption and embedding methods fixed bacteria on the surface of biochar, and the effects of the embedding method on the pore structure and functional groups of biochar was significantly greater than that of the adsorption method. In comparison, adsorbed microorganisms biochars showed a higher efficiency in removing NH₄⁺-N from the waste water than the embedded microorganisms biochars.