果壳种类对生物膜特性及废水处理效果的影响

为促进植物果壳的资源化利用，选择花生壳、核桃壳和夏威夷果壳3种果壳，使用SEM和FTIR表征其表面微观特征与化学基团，探索植物果壳作为SBBR反应器填料的可行性，考察果壳类型对生物膜特性和废水处理效果的影响。结果表明：3种果壳表面粗糙多孔且富有OH、COOH等亲水性基团，有利于微生物附着生长。花生壳上生物膜量呈现“先增后降”变化，试验前期从6.80 mg·cm^-3上升至24.66 mg·cm^-3。后期花生壳软化分解，生物膜量不断降低，与试验前期基本持平，生物膜中夹杂过多腐烂的代谢产物，导致EPS含量最低（49.90 mg·g^-1），DHA低，生物膜活性差，对COD、NH₄⁺-N长期去除效果不理想，仅能达到约65%；核桃壳、夏威夷果壳上生物膜量含量高，试验前期分别从7.98 mg·cm^-3和8.45 mg·cm^-3快速上升至26.75 mg·cm^-3和25.96 mg·cm^-3，之后缓慢上升。悬浮于反应器中的核桃壳受到强烈水力剪切作用，污染物传质效果的增强促进微生物EPS分泌，EPS含量最高达66.44 mg·g^-1；2种果壳生物膜DHA均呈现“先增后稳”变化，最高达到81.72 mg·g^-1·h^-1，生物膜活性高，对COD、NH₄⁺-N去除率不断增长，最高均达到90%左右。因此，除花生壳外，核桃壳和夏威夷果壳结构稳定，生物膜特性良好、污染物去除效果较好，可作为填料长期使用。

Influence of types of plant husk carriers on biofilm characteristics and wastewater treatment

This study aimed to improve the utilization of plant husks by investigating the potential of three waste plant husks from Arachis hypogaea Linn., Juglans regia, and Macadamia ternifolia F. Muell. The surface microstructures of these husks were characterized via scanning electron microscopy(SEM), and their chemical groups were analyzed via Fourier transform infrared spectroscopy(FTIR), to explore their feasibility as carriers to be used in sequencing batch biofilm reactors. The results showed that the surfaces of the husks were rough, porous, and rich in hydrophilic chemical groups such as OH and COOH. These characteristics are favorable for microbial attachment. The biofilm biomass of peanut husks quickly increased from 6.80 mg·cm^-3 to 24.66 mg·cm^-3 in the early test stage and then slowly decreased. Due to softening and decomposition, the biofilm biomass of peanut husks was continuously decreasing, until it reached the same level as the early test stage. Too many decaying metabolites accumulating in the biofilm gave rise to peanut husks producing the lowest extracellular polymeric substance(EPS)content(49.90 mg·g^-1)and lower docosahexaenoic acid(DHA)content in the biofilm, with poor and high removal rate of chemical oxygen demand(COD)and NH₄⁺-N(about 65%). Walnut and macadamia husks showed higher biofilm biomass, and the biomass increased rapidly from 7.98 mg·cm^-3 to 26.75 mg·cm^-3 and from 8.45 mg·cm^-3 to 25.96 mg·cm^-3, respectively, in the early test stage, followed by slower increases. Suspended in the reactor wastewater, walnut husks were subjected to strong hydraulic shear action, which enhanced the mass transfer effect of pollutants in the biofilm and promoted the microbial secretion of EPS, resulting in the highest EPS content of the tested husks(66.44 mg·g^-1). The DHA contents of the two biofilms first increased and then stabilized, and the highest DHA content measured was 81.72 mg·g^-1·h^-1, indicating high biofilm activity. The two kinds of plant husks exhibited increasing removal rates of COD and NH₄⁺-N, with the highest measured rate being around 90%. Walnut and macadamia husks were therefore suitable long-term carriers, as their structures were stable, their biofilm characteristics were optimal, and their pollutant removal effects were sufficient.