A comparative study of removal efficiency of organic contaminant in landfill leachate-contaminated groundwater under micro-nano-bubble and common bubble aeration

Abstract

Land ll leachate contaminated groundwater is widespread all over the world. In order to study the organic contaminant removal e ciency of land ll leachate contaminated groundwater under oxygen micro-nanobubble (MNB) aeration, a series of lab-scale experiments of oxygen MNB aeration as well as common bubble (CB) aeration were conducted. On the one hand, the difference of mass transfer, microbial activity enhancement and contaminant removal e ciency between MNB and CB aeration were estimated. On the other hand, the composition variations of dissolved organic matter (DOM) in groundwater treated by MNB or CB aeration were characterized by ultraviolet-visible (UV-VIS) absorption spectrum and uorescence excitation-emission matrix (EEM). The test results showed that the oxygen utilization e ciency and volumetric oxygen transfer coe cient of MNB aeration were 10 and 50 times that of oxygen CB aeration, respectively. On the 30th day after MNB aeration, the dehydrogenase activity (DHA) of groundwater increased by 101.25%. Compared with CB aeration, the chemical oxygen demand (COD), 5-day biochemical oxygen demand (BOD 5 ) and ammonia nitrogen removal e ciency under MNB aeration increased by 29.72%, 13.43% and 138.59%, respectively. With the biodegradation effect of MNB aeration, a large number of protein-like and soluble microbial by-product substances were degraded, and humic and fulvic acid-like substances were degraded to a certain level. Oxygen MNB aeration played a chemical oxidation effect while enhancing the biodegradation of groundwater, and it was an energy-e cient land ll leachate contaminated groundwater treatment method.

Removal efficiency of organic contaminants in landfill leachate contaminated groundwater under oxygen micro–nano bubble aeration

“…Therefore, the DO concentration increased quickly and reached the maximum of 38.5 mg L −1 within 120 s. Then, the oxygen dissolution and overflow in groundwater reached equilibrium gradually with time, and the DO kept its peak value of 38.5 mg L −1 until the end of MNB aeration. According to Bai et al 39 and Hu and Xia, 40 the DO peak value in conventional oxygen aeration was about 8 mg L −1 . The high DO peak value indicated that MNB aeration effectively increased the DO concentration of groundwater.…”

“…Based on a previous study, 39 the preliminary energy consumption in MNB and conventional aeration were estimated. Specifically, in order to obtain the DO value of 8 mg L −1 in groundwater, oxygen MNB and conventional aeration lasted for 8 seconds and 5 minutes, respectively.…”

Review of Micro- and Nanobubble Technologies: Advancements in Theory and Applications and Perspectives on Adsorption Cooling and Desalination Systems

“…Over time, the technology and knowledge regarding nanobubbles (NBs) have continued to evolve and they are now gaining more and more applications, such as in water treatment [8], agriculture [9] and drug delivery [10]. Due to their unique properties, such as large specific area, high mass transfer efficiency and low rising velocity in liquid, nanobubbles have become popular research objects [11][12][13][14]. A model presented in [15] shows promising results for the use of cavitation to enhance heat transfer, as cavitation can thin the thermal boundary layer, reduce thermal resistance and improve heat transfer.…”