Reactive Transport and Removal of Nutrients and Pesticides in Engineered Porous Media

Abstract

Agricultural nonpoint pollution has been recognized as a primary source of nutrients and pesticides that contaminate surface water and groundwater. Reactive materials have great potential to remove nutrients and pesticides from agricultural drainage water. In this study, we investigated the reactive transport and removal of coexisting nitrate, phosphate, and three pesticides (tricyclazole, isoprothiolane, and malathion) by iron filings and natural ore limestone through column experiments under saturated flow conditions. Breakthrough results showed that 45.0% and 35.8% of nitrate were removed by iron filings and limestone during transport, with average removal capacities of 2670 mg/kg and 1400 mg/kg, respectively. The removal of nitrate was mainly due to microbial denitrification especially after 131–154 pore volumes (≈30 d), whereas reduction to ammonia dominated nitrate removal in iron filings during early phase (i.e., <21.7 d). The results showed that 68.2% and 17.6% of phosphate were removed by iron filings and limestone, with average removal capacities of 416.1 mg/kg and 155.2 mg/kg, respectively. Mineral surface analyses using X-ray diffraction (XRD) and scanning electron microscope (SEM) coupled with energy-dispersive X-ray analysis (EDX) suggested that ligand exchange, chemical precipitation, and electrostatic attraction were responsible for phosphate removal. Chemical sorption was the main mechanism that caused removals of 91.6–100% of malathion and ≈27% of isoprothiolane in iron filings and limestone. However, only 22.0% and 1.1% of tricycalzole were removed by iron filings and limestone, respectively, suggesting that the removal might be relevant to the nonpolarity of tricyclazole. This study demonstrates the great potential of industrial wastes for concurrent removal of nutrients and pesticides under flow conditions.

Effects of Drying-Rewetting Cycles on Ferrous Iron-Involved Denitrification in Paddy Soils

“…When switching from drying status to flooding condition, there would be more ferrous iron which can devote electron ion to oxidizing substances (e.g., nitrate). Since the nitrate-dependent iron-oxidizing bacteria was detected in a lagoon, various denitrifying bacteria which can oxidize ferrous iron with nitrate have been found [16,17]. Melton et al [18] systematically described the process of Fe 2+ oxidation by nitrate with the denitrifying bacteria in the sedimentary and terrestrial environments.…”

Insight into particle detachment in clogging of porous media; a pore scale study using lattice Boltzmann method

“…Understanding attachment and detachment of fine particles in porous media is critical in several applications including chemical ( Stewart and Buriak, 2000 ) environmental (( Abdul Mujeebu et al, 2009 ); , and petroleum technologies, oil exploitation (Parazzo et al, 2018), industrial filtering ( Netter and Conti, 2016 ), groundwater utilization ( Chequer et al, 2019 ;Wang et al, 2020 ), grouting engineering ( Zhou et al, 2018 ) and industrial waste disposal ( Tong et al, 2019 ). Several approaches including experimental ( Bergendahl and Grasso, 2000 ;Silliman et al, 2001 ;( Haque et al, 2017 ), Chu et al, 2019 ), computational ( Raoof et al, 2013 ;Klimenko and Maryshev, 2019 ;( Benioug et al, 2017;Gaebler and Eberl, 2018 ), Yoon et al 2015 ;andmathematical ( Bedrikovetsky et al, 2011 , ( Bedrikovetsky et al, 2012 ), Bergendahl and Grasso, 2000 ;Schulz and Knabner, 2016 ) methods have been developed, focusing on particle transport, attachment, and detachment of colloids in porous media.…”