Ammonium-nitrogen-contaminated groundwater remediation by a sequential three-zone permeable reactive barrier (multibarrier) with oxygen-releasing compound (ORC)/clinoptilolite/spongy iron: column studies

Abstract

A novel sequential permeable reactive barrier (multibarrier), composed of oxygen-releasing compound (ORC)/clinoptilolite/spongy iron zones in series, was proposed for ammonium-nitrogen-contaminated groundwater remediation. Column experiments were performed to: (1) evaluate the overall NH4(+)-N removal performance of the proposed multibarrier, (2) investigate nitrogen transformation in the three zones, (3) determine the reaction front progress, and (4) explore cleanup mechanisms for inorganic nitrogens. The results showed that NH4 (+)-N percent removal by the multibarrier increased up to 90.43 % after 21 pore volumes (PVs) at the influent dissolved oxygen of 0.68∼2.45 mg/L and pH of 6.76∼7.42. NH4(+)-N of 4.06∼10.49 mg/L was depleted and NOx(-)-N (i.e., NO3 (-)-N + NO2(-)-N) of 4.26∼9.63 mg/L was formed before 98 PVs in the ORC zone. NH4(+)-N of ≤4.76 mg/L was eliminated in the clinoptilolite zone. NOx(-)-N of 10.44∼12.80 mg/L was lost before 21 PVs in the spongy iron zone. The clinoptilolite zone length should be reduced to 30 cm. Microbial nitrification played a dominant role in NH4(+)-N removal in the ORC zone. Ion exchange was majorly responsible for NH4(+)-N elimination in the clinoptilolite zone. Chemical reduction and hydrogenotrophic denitrification both contributed to NOx(-)-N transformation, but the chemical reduction capacity decreased after 21 PVs in the spongy iron.

Ammonium-Nitrogen (NH4+-N) Removal from Groundwater by a Dropping Nitrification Reactor: Characterization of NH4+-N Transformation and Bacterial Community in the Reactor

“…The in situ permeable reactive barrier (PRB) is a promising groundwater NH 4 + -N removal technology. Several laboratory-and full-scale PRBs have effectively removed NH 4 + -N from groundwater [6,8,[11][12][13]. Although a PRB is cost-effective in the long term, it, nonetheless, requires large-scale construction and incurs a high initial cost [14].…”

Nitrogen removal from ammonium-contaminated groundwater using dropping nitrification–cotton-based denitrification reactor

“…Groundwater is also used for agricultural (El-Din et al 2021;Zhao et al 2021) and industrial purposes (Amiri et al 2021;Rao et al 2021). However, groundwater is contaminated with ammonium-nitrogen (NH 4 þ -N) in many countries (Patterson et al 2002;Lindenbaum 2012;Huang et al 2015;Choudhary et al 2016;Shakya et al 2019) at levels higher than the limit set by the World Health Organization for drinking water (WHO 2011). Also, NH 4 þ -N remains for longer time in groundwater due to hydro-geochemical conditions (Bohlke et al 2006;Atta & Yaacob 2015).…”

Electrolysis-Driven Bioremediation to Enhance Nitrogen and Phosphorus Removal From Polluted River Sediment

“…Therefore, increasing oxygen availability has long been regarded as a way to reduce NH 3 -N and PO 4 3− -P in anaerobic sediment environments (Wang et al 2020). The use of oxygen-releasing compounds (ORC) based on calcium or magnesium peroxide has been proposed as a strategy to ensure a long-lasting release of oxygen for NH 3 -N removal in contaminated subsurface anaerobic sediment and released Mg 2+ and Ca 2+ ions for the PO 4 3− -P control (Huang et al 2015;Yang et al 2015;Seifan et al 2017;Li et al 2020). However, a number of drawbacks have prevented the use of ORC for the remediation process, including: (i) the rate of oxygen release and the resulting oxygen availability is di cult to control; (ii) repeated injections may be required due to the oxygen consumption/scavenging by biotic and abiotic side reactions, (iii) ORC may have secondary harmful effects on microbe and aquatic biota such as higher pH environment was caused as hydroxide will produced during process of ORC release oxygen.…”