source:LASEN Environmental Protection release date:2025-12-12 Number of reads:73
Polyacrylamide is a water-soluble polymer with polar amide groups, which can easily adsorb onto the surface of sediment particles through hydrogen bonding. It also possesses long molecular chains that provide an immense adsorption surface area in water, resulting in excellent flocculation effects. These long chains form bridges between particles, creating large flocculent aggregates with functions such as flocculation and thickening. Polyacrylamide is commonly used in key industries including textiles, petroleum production, agriculture, and animal husbandry. In wastewater treatment, cationic polyacrylamide and polyaluminum chloride are frequently employed as coagulants. The biological granulation fluidized bed enhances coagulation and granulation through the addition of PAM, while simultaneously utilizing the biochemical degradation effects of granular sludge to optimize the quality of the effluent water. The microorganisms in activated sludge are primarily composed of fungi, bacteria, protozoa, and metazoa. The living characteristics of microbial populations within the sludge are of critical importance to the effectiveness of wastewater treatment.
Currently, there are numerous methods available for analyzing microbial populations; for example, traditional selective culture media and denaturing gradient gel electrophoresis (DGGE) are both effective approaches for examining microbial communities. Since the 1980s, molecular biology...
techniques have been widely applied to the analysis of microbial community structure. Fluorescence in situ hybridization (FISH) has gained prominence because it enables rapid and accurate qualitative and quantitative identification of microorganisms, revealing their species composition and diversity.
It has become an effective tool for environmental microbiological analysis. Currently, there are few studies on microbial utilization of PAM, and even less is known about its impact on microbial communities. Therefore, this study investigates the effects of long-term PAM dosing on pollutant degradation and employs fluorescence in situ hybridization (FISH) technology to examine the microorganisms within the reactor, thereby revealing changes in the microbial community structure.
The conclusions are as follows:
(1) Using raw wastewater with a self-prepared organic load as influent and activated sludge from an oxidation ditch as seed sludge, the system was operated long-term under conditions of 25 °C, an aerobic/anoxic ratio of 3:1, and no sludge recirculation. The results showed that polyacrylamide (PAM) promoted the growth of microorganisms in the activated sludge.
(2) A certain concentration of polyacrylamide (PAM) enhanced the settleability of the sludge and improved the removal of both COD and ammonium nitrogen (NH₄⁺-N) from the wastewater.
(3) When the influent COD loading remained stable, the microbial community was relatively stable, with ammonia-oxidizing bacteria (AOB) significantly outnumbering nitrite-oxidizing bacteria (NOB), making AOB the dominant population. Upon addition of polyacrylamide (PAM), the total bacterial count as well as the abundances of both nitrite-oxidizing and ammonia-oxidizing bacteria increased, indicating that PAM promoted the enrichment and growth of nitrifying and ammonia-oxidizing bacteria.
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