Zhan Yuanhang, Yin Fubin, Yue Caide, Zhu Jun, Zhu Zhiping, Zou Mengyuan, Dong Hongmin
Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701, USA.
Membranes (Basel). 2020 Sep 23;10(10):249. doi: 10.3390/membranes10100249.
Nanofiltration (NF) or reverse osmosis (RO) process has been widely applied for concentrating nutrient in biogas digestate. However, efficient pretreatment is key to the sustainable operation of NF or RO. In this study, the combination of NF and RO for concentrating biogas digestate was compared using different pretreatments of hollow fiber ultrafiltration membrane (HFUFM) and ceramic membrane (CUFM). Pilot-scale batch tests were conducted (500 L). CUFM showed a higher membrane flux than HFUFM (100 ~ 180 L·(m·h) vs. 17 ~ 35 L·(m·h)), but they showed little impact on the NF + RO process. Membrane fluxes of NF and RO were 20 ~ 48 L·(m·h) and 16 ~ 40 L·(m·h), respectively. In the RO permeates, the removal rates of total suspended solids (TSS), total solids (TS), chemical oxygen demand (COD), total nitrogen (TN), NH-N, and Cl were above 91%. In the concentrates, TN and total potassium (TK) were concentrated by 1.60 and 2.00 folds in the NF stage, and by 2.10 and 2.30 folds in the RO stage. Further attention should be paid to the antibiotics risks in the concentrates before they are utilized as plant fertilizers.
纳滤（NF）或反渗透（RO）工艺已被广泛应用于浓缩沼气消化液中的养分。然而，高效的预处理是纳滤或反渗透可持续运行的关键。在本研究中，使用中空纤维超滤膜（HFUFM）和陶瓷膜（CUFM）的不同预处理方法，比较了纳滤和反渗透联合用于浓缩沼气消化液的效果。进行了中试规模的间歇试验（500升）。陶瓷膜显示出比中空纤维超滤膜更高的膜通量（100180升·（平方米·小时）对1735升·（平方米·小时）），但它们对纳滤+反渗透工艺的影响很小。纳滤和反渗透的膜通量分别为2048升·（平方米·小时）和1640升·（平方米·小时）。在反渗透渗透液中，总悬浮固体（TSS）、总固体（TS）、化学需氧量（COD）、总氮（TN）、氨氮和氯离子的去除率均高于91%。在浓缩液中，总氮和总钾在纳滤阶段分别浓缩了1.60倍和2.00倍，在反渗透阶段分别浓缩了2.10倍和2.30倍。在将浓缩液用作植物肥料之前，应进一步关注其中的抗生素风险。
