Electrolytic groundwater circulation well for trichloroethylene degradation in a simulated aquifer

An in situ groundwater remediation process, termed EGCW, was developed in this study by integrating in-well groundwater electrolysis into groundwater circulation well. Groundwater circulation carries electrolytically generated O2 and H2 into the impacted aquifer for in situ biodegradation of contaminants. In a two-dimensional tank filled with field sandy sediments,simulated trichloroethylene(TCE)-contaminated groundwater was circulated between an injection well with electrodes inside and a pumping well. Results from a 50-day EGCW experiment show that in-well electrolysis oxygenated most region near the injection well, and 10 mg/L TCE was mainly biodegraded aerobically to about 2.7 mg/L(73% removal) by the indigenous microbes. Aerobic TCE degradation was enhanced by the pulsed addition of acetate. Together with the proofs of stable carbon isotope fractionation(enrichment factor:-0.57‰–-1.53‰) and microbial community variation after EGCW treatment, aerobic cometabolism was proposed to be the most likely mechanism for TCE degradation. It is interesting to find that the intrinsic organic carbon in aquifer matrix could fuel the aerobic TCE degradation, particularly at low TCE concentrations. EGCW treatment is advantageous in terms of supplying appropriate dosages of electron acceptor(O_(2)) and donor(H_(2)) for in situ bioremediation because groundwater electrolysis and circulation are expedient and controllable.

A Simulation Study on the Evolution of Groundwater Circulation Systems in Cenozoic Basins of Northern China

Three Cenozoic basins—the Qaidam basin, the Weihe graben-type basin and the North China plain—which are different in climatic conditions, geological settings and run—off types, are selected for the study. Based on an analysis of background information of the transect along the middle-latitude region, studies of groundwater dynamics, geochemistry, simulation of water circulation of the main elements as well as isotopic chronology, the information on global changes is collected, the formation of groundwater circulation systems and their evolution under stacked impacts of natural conditions and human activities are discussed, and a correlation is made between the evolutionary features of the above systems in these basins since 25 ka B.P. All these have laid a good foundation for further generalizing the evolutionary model of land water in northern China.

Characteristics of groundwater in Northeast Qinghai-Tibet Plateau and its response to climate change and human activities:A case study of Delingha,Qaidam Basin

Delingha is located in the northeast margin of Qaidam Basin.Bayin River alluvial proluvial fan is the main aquifer of Delingha,in which groundwater generally flows from north to south.The hydrochemistry results showed that two different hydrochemical evolution paths formed along southeast and southwest directions,respectively.Cl-Na type groundwater was formed in front of Gahai Lake,and SO_(4)·HCO_(3)-Na·Ca type groundwater was formed in front of Keluke Lake.The results of deuterium(D)and 18O revealed that the groundwater mainly originated from the continuous accumulation of precipitation during geological history under cold and humid climate conditions.In addition,results of ^(14)C indicated that the groundwater age was more than 1140 years,implying relatively poor renewal capability of regional groundwater.Moreover,our numerical modeling results showed that the regional groundwater level will continue to rise under the warm and humid climate conditions.

Real-Time Monitoring of Meteorological Data at In-Situ GCW Remediation Sites

To optimize the self-organization network, self-adaptation, real-time monitoring, remote management capability, and equipment reuse level of the meteorological station supporting the portable groundwater circulation wells, and to provide real-time and effective technical services and environmental data support for groundwater remediation, a real-time monitoring system design of the meteorological station supporting the portable groundwater circulation wells based on the existing equipment is proposed. A variety of environmental element information is collected and transmitted to the embedded web server by the intelligent weather transmitter, and then processed by the algorithm and stored internally, displayed locally, and published on the web. The system monitoring algorithm and user interface are designed in the CNWSCADA development environment to realize real-time processing and analysis of environmental data and monitoring, control, management, and maintenance of the system status. The PLC-controlled photovoltaic power generating panels and lithium battery packs are in line with the concept of energy saving and emission reduction, and at the same time, as an emergency power supply to guarantee the safety of equipment and data when the utility power fails to meet the requirements. The experiment proves that the system has the characteristics of remote control, real-time interaction, simple station deployment, reliable operation, convenient maintenance, and green environment protection, which is conducive to improving the comprehensive utilization efficiency of various types of environmental information and providing reliable data support, theoretical basis and guidance suggestions for the research of groundwater remediation technology and its disciplines, and the research and development of the movable groundwater cycling well monitoring system.