| Dicarboxylic acid is an important fine chemical raw material,which is widely used in manufacturing,agriculture,medicine,materials,and aerospace industries.Biological fermentation is currently the main process for the production of dicarboxylic acids,and a large amount of dicarboxylic acid fermentation wastewater(hereinafter referred to as "dicarboxylic acid wastewater ")will be generated during the production processes.The high concentrations of COD,SO42-and TP in dicarboxylic acid wastewater tends to impact the wastewater treatment system.Aerobic granular sludge technology has the advantages of compact sludge structure,good settleability,high treatment load,and strong impact resistance,which shows wide application prospects in treating high salt and high COD wastewater.In this paper,the dicarboxylic acid wastewater was targeted as the research object,and the physicochemical pretreatment agents were selected in terms of bioreactor operational performance and activated sludge characteristics.The effects of SO42concentration on the cultivation of aerobic granular sludge,pollutant removal,and microbial community structure in a sequencing batch reactor(SBR)were investigated.The pollutant removal efficiency,granular sludge characteristics,microbial community and phosphorus removal mechanism in aerobic granular sludge system were investigated for the treatment of dicarboxylic acid wastewater.The results showed that the use of Ca(OH)2 as a physicochemical pretreatment agent had little effect on COD removal,EPS secretion,dehydrogenase activity,and catalase activity of activated sludge,while the agent of polymerized aluminum chloride(APC)+CaCl2 inhibited the growth and metabolism of microorganisms.The TP removal rate decreased significantly with the increase of SO42-concentration,the removal rates of COD,TN,and NH4+-N could be maintained above 96.0%,79.0%,and 95.0%respectively under the concentration of SO42-less than 2000 mg/L,but decreased at SO42-concentration of 3000 mg/L.High salinity resulted in promoting sludge granulation and affecting pollutant removal performance.Aerobic granular sludge technology is efficient in the treatment of dicarboxylic wastewater efficiently.The percentage of sludge granular reached over 95.2%and the granules>0.9 mm was up to 77.4%.The average removal efficiency of COD and TP was 95.1%and 69.9%,respectively.The TP removal was achieved by the adsorption of EPS and the growth of PAOs in large particles.However,the removal capacity of TN and NH4+-N was limited,with an average removal rate of only 39.4%and 36.6%,respectively.The dominant microorganisms were enriched in the granular sludge with ability of dicarboxylic acid degradation,reducing microbial community diversity and abundance.The dominant phyla were Proteobacteria and Bacteroidota,which played an important role in promoting sludge aggregation and pollutant degradation.The dominant bacterial genera were unclassified_f_Comamonadacea and Ottowia,which were the main functional bacterial genera for organic matter degradation. |
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