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抗生素被大量地用于人和动物的疾病治疗,高达85%以上抗生素以原形或代谢物形式排入环境,严重威胁人类的健康[1]。四环素类抗生素是环境介质中抗生素残留的主要来源,相当高比例的四环素通过城市污水管网进入污水处理系统,继而在污泥中积聚。在污泥资源化处理过程中,有效降低四环素含量具有重要意义。
蚯蚓过腹处理城市生活污泥是一种已被广泛认可的处理技术[2],能够显著提升污泥中脱氢酶的活性和放线菌、细菌与根瘤菌的丰度,加速有机物的降解,促进蚯蚓粪的腐殖质化,同时显著降低污泥中四环素和氟喹诺酮的抗性基因[3]。抗生素与蚯蚓有明显的互作效应,物料中阿苯达唑浓度达到5 mg·kg−1时显著影响蚯蚓的繁殖,当其浓度达10 mg·kg−1时,53%的蚯蚓死亡[4]。金霉素浓度的增加及暴露时间的延长导致蚯蚓体重下降,而可溶性蛋白含量显著上升[5]。
现有研究重点关注蚯蚓处理过程改变污泥性质特征以及抗生素对蚯蚓生长的影响,而蚯蚓对污泥中抗生素的消解效率、污泥中抗生素含量对蚯蚓处理污泥效果的影响鲜有报道。本研究以环境中广泛存在的四环素为研究对象,采用微宇宙实验法探究了蚯蚓吞食过腹污泥过程中对四环素的降解效果以及对污泥中大量营养元素赋存的影响特征,为蚯蚓处理污泥的产业化发展提供参考。
蚯蚓过腹处理对污泥中四环素降解及大量营养元素赋存的影响
Effect of earthworm swallowing on the tetracycline degradation and accumulation of macro-mineral element in sewage sludge
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摘要: 针对污泥中大量抗生素残留对环境的威胁和污泥资源化利用的瓶颈等问题,采用微宇宙实验手段研究了蚯蚓过腹处理污泥过程中四环素的降解特征和污泥蚓粪中大量营养元素的赋存特征。结果表明,污泥中的四环素降解率与处理时间呈正相关关系;室温静置32 d后,污泥中9%~11%的四环素发生降解。蚯蚓过腹处理下,污泥中四环素浓度与四环素降解率呈负相关关系,随着污泥中四环素浓度的增加,四环素降解率逐渐降低,蚯蚓过腹处理32 d后,污泥中四环素的降解率提升了45%~64%。蚯蚓过腹形成的污泥蚓粪中总氮和有机质含量显著减低,而铵态氮、硝态氮、速效磷、速效钾和总钾含量以及pH和电导率均显著升高;随着污泥中四环素浓度的增加,污泥蚓粪中总氮和氨氮含量以及pH和电导率呈显著降低趋势;污泥蚓粪中铵态氮和硝态氮含量、pH和电导率与四环素降解率均呈正相关关系。蚯蚓过腹处理能够显著提升污泥中四环素的降解率及污泥蚓粪中速效氮磷钾的含量。Abstract: In order to solve the environmental pollution problem that caused by large amount of residual antibiotics in the sludge and sludge resource utilization, the laboratory-controlled sludge microcosms was used to study the effect of earthworm swallowing on the tetracycline degradation and accumulation of macro-mineral element in sewage sludge. The results showed that the degradation rate of tetracycline in sludge was positively correlated with treatment time. After 32 days static treatment (no adding earthworms to sludge) at indoor temperature, only 9%~11% tetracycline was degraded. Under the earthworms digestion treatment (adding earthworms to sludge), the tetracycline concentration was negatively correlated with its degradation rate. With the increase of the concentration of tetracycline in sludge, its degradation rate decreased. The degradation rate of tetracycline under the earthworm digestion treatment increased by 45%~64%. The total nitrogen and organic matter content in the vermicompost significantly decreased, while the ammonium nitrogen, nitrate nitrogen, available phosphorus, available potassium and total potassium content, pH and EC significantly increased. With the increase of tetracycline concentration in sludge, the total nitrogen and ammonia nitrogen content, pH and EC significantly decreased. The ammonium nitrogen, nitrate nitrogen, pH and EC value in the vermicompost were positively correlated with the degradation rate of tetracycline. In summary, the treatment of adding earthworms to sludge can significantly improve the degradation rate of tetracycline in sludge and the available nutrients in vermicompost.
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表 1 污泥碳、氮、磷、钾全量变化特征
Table 1. Variation characteristics of organic carbon, total nitrogen, phosphorus and potassium contents in sludge
g·kg−1 项目 处理方式 总氮 总磷 总钾 有机碳 实验结果 处理组S 23.406a 12.290a 3.832b 166.821a 处理组E 20.051b 12.551a 4.039a 146.781b 处理时间14 d 23.199a 12.078a 3.550b 163.503a 处理时间32 d 20.157b 12.763b 4.321a 150.092b 四环素浓度0 mg·kg−1 25.296a 12.796a 3.750b 159.108a 四环素浓度5 mg·kg−1 21.629b 12.117a 4.040ab 161.769a 四环素浓度25 mg·kg−1 20.202b 12.220a 3.840ab 155.574a 四环素浓度125 mg·kg−1 19.808b 12.548a 4.170a 150.783a 数据分析 处理组 ** NS ** ** 处理时间 ** * ** ** 四环素浓度 ** NS NS NS 处理组-处理时间 ** NS ** NS 处理组-四环素浓度 NS NS ** NS 处理时间-四环素浓度 NS NS * NS 处理组-处理时间-四环素浓度 NS NS NS NS 注:表中同一列相同影响因子后的不同小写字母表示同一影响因子下不同处理间差异显著(P<0.05);NS表示无显著差异;*表示P<0.05;**表示P<0.01。 表 2 污泥氮、磷、钾元素有效态含量、pH及电导率的变化特征
Table 2. Variation characteristics of available nitrogen, phosphorus and potassium contents, pH and EC in sludge
项目 处理方式 铵态氮/
(g·kg−1)硝态氮/
(g·kg−1)速效磷/
(g·kg−1)速效钾/
(g·kg−1)pH 电导率/
(mS·cm−1)实验结果 处理组S 0.575b 0.718b 0.778b 0.616a 7.377a 1.696b 处理组E 2.384a 2.063a 1.047a 0.650a 6.390b 4.243a 处理时间14 d 0.208b 1.226b 0.802b 0.654a 6.737b 2.793b 处理时间32 d 2.750a 1.555a 1.023a 0.612a 7.031a 3.148a 四环素浓度0 mg·kg−1 1.586a 1.417a 0.877a 0.653a 6.959a 3.216a 四环素浓度5 mg·kg−1 1.348a 1.372b 0.849a 0.592a 6.922a 2.892b 四环素浓度25 mg·kg−1 1.449a 1.370b 0.951a 0.645a 6.866a 2.893b 四环素浓度125 mg·kg−1 1.535a 1.402b 0.972a 0.641a 6.787b 2.880b 数据分析 处理组 ** ** ** * ** ** 处理时间 ** ** ** NS ** ** 四环素浓度 ** NS NS NS ** ** 处理组-处理时间 ** ** NS NS NS ** 处理组-四环素浓度 ** NS NS NS ** ** 处理时间-四环素浓度 NS ** NS NS NS NS 处理组-处理时间-四环素浓度 ** ** NS NS NS NS 注:表中同一列相同影响因子后的不同小写字母表示同一影响因子下不同处理间差异显著(P<0.05);NS表示无显著差异;*表示P<0.05;**表示P<0.01。 表 3 蚯蚓消解污泥过程中四环素降解率和污泥理化性质相关系数
Table 3. Correlation coefficients between tetracycline degradation rate and sludge physical and chemical properties during the earthworm digestion process
处理组 TN TP TK OC ${\rm{NH}}_4^ + $ -N${\rm{NO}}_3^ - $ -NAP AK pH EC S 0.078 0.277 0.211 −0.049 0.501* −0.580* 0.151 −0.325 0.662** 0.300 E −0.34 0.117 0.431 −0.298 0.798** 0.599** 0.294 0.417 0.573** 0.515* 注:*表示P<0.05;**表示P<0.01。 -
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