Acta Agriculturae Zhejiangensis ›› 2023, Vol. 35 ›› Issue (6): 1407-1415.DOI: 10.3969/j.issn.1004-1524.2023.06.18

• Environmental Science • Previous Articles     Next Articles

Effect of struvite precipitation pretreatment on membrane concentration process of piggery biogas slurry

XIAO Hua1(), XU Xing1, XIE Chuanqi1, ZHOU Xin1, ZHOU Weidong1,*(), TANG Wensheng2,*()   

  1. 1. Institute of Animal Husbandry and Veterinary Science, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
    2. Institute of Animal Husbandry and Veterinary Science, Huangyan Bureau of Agriculture and Rural Affairs, Taizhou 318020, Zhejiang, China
  • Received:2022-06-21 Online:2023-06-25 Published:2023-07-04

Abstract:

Biogas slurry contains a large amount of suspended solids, organic matters and inorganic salts, which would cause serious membrane pollution and rapid decline of membrane flux during membrane concentration. In the present study, struvite precipitation was used as the pretreatment, to explore its effect on slowing down membrane fouling rate and improving the filtration efficiency of membrane. It is proved that after struvite precipitation, the turbidity, electrical conductivity and ammonia nitrogen concentration of biogas slurry are greatly reduced. The struvite precipitation increases the membrane flux and volume reduction factor of subsequent ultra filtration (UF) and reverse osmosis (RO). The turbidity removal efficiency of biogas slurry by UF is more than 99%, and the turbidity of UF permeate is less than 2.0 NTU. The struvite precipitation improves CODCr (chemical oxygen demand) removal rate of biogas slurry by UF, and enhances the removal efficiency of CODCr and salinity by RO. The CODCr, ammonia nitrogen concentration and electrical conductivity of the final effluent are 135 mg·L-1, 21 mg·L-1, 0.16 mS·cm-1. All these quality parameters are better than those of the effluent without struvite precipitation, and satisfiy the limit of national standards of GB 5084—2021 Standard for irrigation water quality and GB 18596—2001 Discharge standard of pollutants for livestock and poultry breeding. It is confirmed that struvite precipitation is an efficient pretreatment for membrane concentration of biogas slurry.

Key words: biogas slurry, struvite precipitation, membrane concentration, ultrafiltration, reverse osmosis

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