The last 60 years has seen unprecedented groundwater extraction and overdraft as well as development of new technologies for water treatment that together drive the advance in intentional groundwater replenishment known as managed aquifer recharge (MAR). This paper is the first known attempt to quantify the volume of MAR at global scale, and to illustrate the advancement of all the major types of MAR and relate these to research and regulatory advancements. Faced with changing climate and rising intensity of climate extremes, MAR is an increasingly important water management strategy, alongside demand management, to maintain, enhance and secure stressed groundwater systems and to protect and improve water quality. During this time, scientific research—on hydraulic design of facilities, tracer studies, managing clogging, recovery efficiency and water quality changes in aquifers—has underpinned practical improvements in MAR and has had broader benefits in hydrogeology. Recharge wells have greatly accelerated recharge, particularly in urban areas and for mine water management. In recent years, research into governance, operating practices, reliability, economics, risk assessment and public acceptance of MAR has been undertaken. Since the 1960s, implementation of MAR has accelerated at a rate of 5%/year, but is not keeping pace with increasing groundwater extraction. Currently, MAR has reached an estimated 10 km3/year, ~2.4% of groundwater extraction in countries reporting MAR (or ~1.0% of global groundwater extraction). MAR is likely to exceed 10% of global extraction, based on experience where MAR is more advanced, to sustain quantity, reliability and quality of water supplies.@en

The cometabolism as a technique for enhancing biodegradation of pentachlorophenol (PCP) has been widely used, but the effect of dosing mode of growth substrates on the cometabolic degradation of PCP in an anaerobic system with and without the addition of ZVI is still not clear. In this study, the effects of dosing modes of sodium acetate as co-substrate, i.e., one-step pulse, evenly distributed pulse, and stepwise declining pulse, and zero-valent iron (ZVI) of 1 mg l−1 on pentachlorophenol (PCP) degradation and changes in anaerobic microbial community were examined in batch tests. The results indicated that the degradation kinetic constants of PCP were related to the dosing mode of co-substrate. The complete mineralization rates of PCP in the two groups with evenly distributed pulse mode and stepwise declining pulse mode were faster than the observed rates of the group with one-step pulse mode, according to the quantitative analysis of 2,3,5,6-tetrachlorophenol, 2,3,5-tetrachlorophenol, and 2,5-chlorophenol. In addition, there was a substantial change in the content of intracellular polysaccharide in the cometabolic process of the one-step pulse and stepwise declining pulse groups. Furthermore, the electron transport system (ETS) activities reached to the maximum values of 0.841 and 0.813 ug g−1 in these two groups with the addition of 1 g l−1 ZVI, respectively. Moreover, Alcaligenes (11.02%), Comamonas (14.58%), and Ralstonia (9.16%) were the dominant genera in the groups with the three co-substrate dosing modes, respectively. This study provides a new insight into achieving anaerobic cometabolic degradation of PCP with different dosing modes of co-substrate.@en