Search

The installed capacity of ultrafiltration (UF) membranes in drinking water treatment plants (DWTPs) has increased significantly, it is necessary to summarize the long-term characteristics of UF membranes in full-scale DWTPs in China. Firstly, the characteristics of UF membranes applied in large-scale DWTPs in China were systematically evaluated based on capacity, location, membrane materials and filtration mode. By 2020, the total capacity of large-scale DWTPs using UF membranes has reached ~10 million m3/d. Polyvinylidene fluoride was the dominant UF membrane material with a proportion of 73.7 %, followed by polyvinyl chloride. Secondly, the performance of UF membranes in various typical DWTPs during long-term operation was analyzed. UF membrane in five typical treatment processes displayed good contaminant removal performance, while the combination of UF membrane with coagulation, sedimentation and filter was widely used. The fouling evolution of UF membranes during long-term operation was systematically analyzed. Then, the effect of pretreatment methods and cleaning approaches on membrane in full-scale DWTPs were assessed. The use of hydraulic cleaning, maintenance cleaning and recovery cleaning could ensure the stable operation of UF membranes, while these cleaning methods may adversely influence membrane lifetime. This study could provide useful guidance for long-term operation of UF membrane in full-scale DWTPs. [Display omitted] • UF membrane in 106 full-scale DWTPs in China reached ~10 million m3/d by 2020. • DWTPs with UF displayed spatial distribution, with most in Eastern China. • Combination of UF with traditional drinking water treatment units employed widely. • PVDF occupied 73.7 % of membrane material and 60 % of UF operated at submerged mode. • Over half of the UF membranes in full-scale DWTPs operated for over 5 years. [ABSTRACT FROM AUTHOR]

The dominant market for lithium-ion batteries (LIBs) in China has driven lithium chemicals with foreseeable growth in demand. Lithium extraction from salt-lake brine in China with high Mg2+/Li+ ratio has become one of the key challenges in the separation of Mg2+ and Li+. In this study, we introduce here an unprecedented, highly permselective nanofiltration hollow fiber membrane prepared by layer-by-layer (LBL) deposition as a novel alternative for Mg2+/Li+ separation. Poly(styrene sulfonate) and poly(allylamine hydrochloride) were deposited alternatively on a tailor-made ultrafiltration hollow fiber support and crosslinking with glutaric dialdehyde. The pure water permeability of LBL NF membrane was 18.4 L m−2 h−1 bar−1. Under the synergistic effect of size sieving and Donnan exclusion effect, it also achieved promising results when tested with simulated brine. The rejection rate of Mg2+ was as high as 99%, and the rejection rate of Li+ was as low as −60%, with a separation factor of 74 was observed, setting a record of permselectivity for Mg2+/Li+ separation for engineerable membranes. This research has paved a new road for the engineering application of LBL nanofiltration membranes for mono and bivalent ion separation. • LBL nanofiltration hollow fiber membrane was used for Mg2+/Li+ separation for the first time. • Exceedingly high permselectivity was observed using PSS/PAH pairs in LBL assembly. • Size sieving was identified as the key factor for Mg2+/Li+ separation. [ABSTRACT FROM AUTHOR]

Abstract: An integrated process including coagulation, ozonation, ceramic membrane ultra-filtration and activated carbon filtration was investigated for the treatment of drinking water from the micro-polluted surface water in the southern China. A pilot-scale plant with the capacity of 120m3/d was set up and operated. Submerged flat-sheet ceramic membranes were selected with the average pore diameter of 60nm and the filtration area of 50m2. Quite a number of water quality parameters were evaluated including turbidity, particle counts, coliform bacteria, Cryptosporidium and Giardia cysts, dissolved organic carbon (DOC), ammonia, geosmin, 2-methylisoborneol (2-MIB), 4 trihalomethanes, 6 haloacetic acids, 8 endocrine disrupting compounds (EDCs) and 14 pharmaceutical and personal care products (PPCPs). The experimental results showed that the removal efficiencies of all the evaluated parameters ranged from 64% to 100%. The ozonation in membrane tank is very helpful both in enhancing the performance of removing multiple contaminants and in controlling the membrane fouling with ozone dosage of 2–5mg/L at the permeate flux of 100L/m2·h. The innovation of the integrated process was discussed based on the concept of nano-reactor to probe into the reaction activities inside the membrane pores. However, the detailed mechanisms need to be explored in the future. [Copyright &y& Elsevier]

Abstract: The wastewater of the Chinese Paper Mill is currently treated with the conventional A–O–O method, which consists of a balance tank, a first sedimentation tank, an anoxic tank, an aerobic tank and a secondary sedimentation tank. The conventional treatment cannot meet the requirements of water quality for the paper making process. The integrated membrane process in pilot scale which consists of the membrane bioreactor (MBR), the continuous membrane filtration (CMF) and the reverse osmosis (RO) is used to treat the wastewater of this paper mill. The discharged water from the first sedimentation tank was treated with the anoxic/aerobic/MBR membrane system to eliminate NH3–N and organic compound dissolved or undissolved. Although the permeate met the quality standards of feed for RO system, the CMF unit before RO system is still used in this integrated system in order to keep RO system operation safely, in case the bad water input the RO unit when the MBR system have some trouble. In this system a low-pressure RO unit with the form of anti-fouling spiral-wound membrane was accepted to purify the influent from CMF unit. The recovery of water for RO system was over 65%. The result showed that the RO permeate with the high quality could meet the whole standards of process water of paper mill. The conductivity of RO permeate was less than 200 μS/cm, COD less than 15 mg/L, the turbidity less than 0.1 NTU, and the chroma of RO permeate was less than 15 PCU. As the result, the treated water by the integrated membrane process could be reused in paper manufacturing process perfectly. [Copyright &y& Elsevier]