University of Maribor, Faculty of Chemistry and Chemical Engineering, Smetanova ul. 17, 2000, Maribor, Slovenia.
University of Maribor, Faculty of Chemistry and Chemical Engineering, Smetanova ul. 17, 2000, Maribor, Slovenia.
J Environ Manage. 2021 Jul 15;290:112593. doi: 10.1016/j.jenvman.2021.112593. Epub 2021 Apr 21.
The aim of this study was to recover nutrients (NPK and other) from the liquid fraction of digestate obtained by rumen fluid enhanced anaerobic co-digestion of sewage sludge and cattail (Typha latifolia grass). Firstly, anaerobic digestion (AD) studies were performed to examine the biogas potential of selected substrates. The liquid fraction of digestate was then used in nutrient recovery experiments. Four methods were applied to recover nutrients: i) conventional struvite precipitation by MgCl, ii) simultaneous precipitation and ion exchange by Na-zeolite, and iii) two-step recovery using precipitation, followed by ion exchange with powdered or iv) granulated Na-zeolite. The products of nutrient recovery were characterised using different chemical methods and the cress seed germination test was performed to evaluate their fertility potential. The results show that co-digestion of sewage sludge with cattail enhanced biogas production by almost 50 vol%. The addition of rumen fluid positively contributed to the degradation of lignocellulosic materials and to biogas production. In all of the recovery methods tested, phosphorus was successfully recovered with efficiency of more than 99 wt%. Nitrogen recovery was less efficient than phosphorus recovery, 85-92 wt%. Simultaneous precipitation and ion exchange lowered nitrogen recovery efficiency compared to classical struvite precipitation, while sequential precipitation and ion exchange resulted in improvement. The most efficient method was two-step recovery using granulated zeolite. The precipitates consisted of different Mg and K-phosphates in quite irregular shapes. The struvite and K-struvite were detected in low quantities. The precipitates contained more than 25 wt% of macronutrients (NPK), exhibited effective utilization of nutrients by plants, and showed good fertility potential. Precipitate mixed with powdered Na-zeolite promises to be interesting for further agricultural use, as zeolite offers several potential improvements for soil. Both zeolites exhibited good performance in the recovery of K ions.
本研究旨在从经瘤胃液强化的厌氧共消化污水污泥和香蒲（香蒲草）获得的消化液的液体部分回收养分（NPK 和其他）。首先，进行了厌氧消化（AD）研究，以检查所选底物的生物气潜力。然后将消化液的液体部分用于养分回收实验。应用了四种方法来回收养分：i）用 MgCl2 进行常规鸟粪石沉淀，ii）用 Na-沸石同时进行沉淀和离子交换，以及 iii）使用沉淀进行两步回收，然后用粉末状或 iv）粒状 Na-沸石进行离子交换。使用不同的化学方法对养分回收产物进行了表征，并进行了荠种子发芽试验以评估其肥力潜力。结果表明，与香蒲共消化污水污泥使沼气产量增加了近 50%。瘤胃液的添加对木质纤维素材料的降解和沼气的产生有积极贡献。在所测试的所有回收方法中，磷的回收率都超过 99%。氮的回收率不如磷的回收率有效，为 85-92%。与经典的鸟粪石沉淀相比，同时沉淀和离子交换降低了氮的回收率效率，而顺序沉淀和离子交换则提高了回收率。最有效的方法是使用粒状沸石进行两步回收。沉淀物以不规则形状包含不同的 Mg 和 K 磷酸盐。检测到少量的鸟粪石和 K 鸟粪石。沉淀物含有超过 25%的大量营养素（NPK），对植物的养分有效利用，并表现出良好的肥力潜力。沉淀与粉末状 Na-沸石混合有望在农业中进一步使用，因为沸石为土壤提供了几种潜在的改进。两种沸石在回收 K 离子方面均表现出良好的性能。
