Abstract:The anaerobically digested piggery slurry (ADPS) is a kind of organic wastewater with high suspended solids (SS) concentration and pollutant load discharged from large-scale pig farm biogas project. The complete solid-liquid separation through bioleaching conditioning followed by diaphragm pressure filter is of significance in ADPS biological purification. The bioleaching conditioning of ADPS with addition of different concentrations of microbial nutrient were performed through the flask-shaking experiment. Acidic already-bioleached ADPS was taken as an inoculum for next batch bioleaching experiment with the recycling ratio of 1∶1, and the corresponding recycling was conducted for successive six batches. The pH, specific resistance to filtration (SRF), heavy metal content in bioleached cake, and water quality indexes were measured. The results showed that when the concentration of microbial nutrient was ≥15 g·L?1, and good and stable bioleaching effect was achieved as following: the pH value and the SRF of bioleached ADPS could drop below 3.5 and about 5.0×1011 m·kg?1, respectively, and their dewaterability could increase by 86.1%. Under such a condition, the leaching percentages of Cu and Zn of the sludge-borne heavy metals were above 49.5% and 72.7%, respectively. After bioleaching treatment, the ADPS volume decreased by 40%~50%. The chemical oxygen demand (COD) content, ammonia nitrogen (NH3) content, total phosphorus (TP) content and SS of the filtered water could decrease to 423.8~499.3, 671.4~704, 0.7~1.1 and 0 mg·L?1 from the initial 27 669.8, 1 014.8, 582.1 and 27 857.1 mg·L?1, and the corresponding highest removal rates could reach 98.5%, 33.8%, 99.8% and 100%, respectively, which greatly reduced the difficulty in subsequent biochemical treatment. Therefore, bioleaching conditioning for ADPS has a good application prospect. Key words:anaerobically digested piggery slurry/ microbial nutrient concentration/ bioleaching/ dewaterability/ heavy metal.
图1营养剂浓度对生物沥浸处理猪场沼液过程中pH的影响 Figure1.Nutrient concentration effect on pH of bioleached ADPS in successive multi-batch trials
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1.College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China 2.Nanjing Bact Environmental Solutions Co. Ltd., Nanjing 211505, China Received Date: 2018-12-24 Accepted Date: 2019-03-22 Available Online: 2019-09-17 Keywords:anaerobically digested piggery slurry/ microbial nutrient concentration/ bioleaching/ dewaterability/ heavy metal Abstract:The anaerobically digested piggery slurry (ADPS) is a kind of organic wastewater with high suspended solids (SS) concentration and pollutant load discharged from large-scale pig farm biogas project. The complete solid-liquid separation through bioleaching conditioning followed by diaphragm pressure filter is of significance in ADPS biological purification. The bioleaching conditioning of ADPS with addition of different concentrations of microbial nutrient were performed through the flask-shaking experiment. Acidic already-bioleached ADPS was taken as an inoculum for next batch bioleaching experiment with the recycling ratio of 1∶1, and the corresponding recycling was conducted for successive six batches. The pH, specific resistance to filtration (SRF), heavy metal content in bioleached cake, and water quality indexes were measured. The results showed that when the concentration of microbial nutrient was ≥15 g·L?1, and good and stable bioleaching effect was achieved as following: the pH value and the SRF of bioleached ADPS could drop below 3.5 and about 5.0×1011 m·kg?1, respectively, and their dewaterability could increase by 86.1%. Under such a condition, the leaching percentages of Cu and Zn of the sludge-borne heavy metals were above 49.5% and 72.7%, respectively. After bioleaching treatment, the ADPS volume decreased by 40%~50%. The chemical oxygen demand (COD) content, ammonia nitrogen (NH3) content, total phosphorus (TP) content and SS of the filtered water could decrease to 423.8~499.3, 671.4~704, 0.7~1.1 and 0 mg·L?1 from the initial 27 669.8, 1 014.8, 582.1 and 27 857.1 mg·L?1, and the corresponding highest removal rates could reach 98.5%, 33.8%, 99.8% and 100%, respectively, which greatly reduced the difficulty in subsequent biochemical treatment. Therefore, bioleaching conditioning for ADPS has a good application prospect.
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