Recovery of nutrients from wastewater by a MgCl₂ modified zeolite and their reuse as an amendment for Cu and Pb immobilization in soil

Abstract

In this study, nutrients in wastewater were simultaneously removed by magnesium modified zeolite, and the precipitates of the nutrient recovery process were applied as a kind of amendment to achieve copper and lead immobilization in contaminated soil. Mg 2+ released from MgCl 2 modified zeolite (Zeo-Mg) in the nutrient recovery process was considered as the magnesium source for struvite crystallization. The optimal efficiencies of nutrient recovery using Zeo-Mg were obtained at pH 9. When the dosage and reaction time were separately controlled at 10 g L À1 and 180 min, the ammonia nitrogen (AN) and phosphate removal efficiencies reached 61.22% and 94.73%, respectively. The high simultaneous nutrient removal efficiencies were attributed to cooperation of Zeo-Mg adsorption and struvite formation. The recovery precipitates, zeolite and MAP (Zeo/MAP), were evidenced as a suitable amendment for both Cu and lead immobilization in soil. At a dosage of 5 g amendment per 50 g soil, the available concentrations of Cu and Pb separately reduced to 278.88 mg kg À1 and 168.36 mg kg À1 under 21 day treatment. On further increase in immobilization time, the available concentrations of Cu and Pb reached a relatively steady state. The acid soluble species of Cu and Pb transformed to more inert reducible and residual species and showed that Cu and Pb were successfully immobilized by Zeo/MAP. According to the experiments and characterization results, zeolite adsorption and phosphate formation were the major immobilization mechanisms of Cu and Pb in contaminated soil.

Preparation of magnetic porous NiFe2O4/SiO2 composite xerogels for potential application in adsorption of Ce(iv) ions from aqueous solution

“…In contrast to other methods, adsorption has shown great promise for selective separation of Pu from HLLW, and nding an effective material to dispose of radioactive waste has become the research focus. There are varieties of adsorbents such as active carbon, [14][15][16] carbon nano-tubes, [17][18][19] zeolites, [20][21][22] molecular sieves, [23][24][25] ionexchange membranes, [26][27][28] and bio-adsorbents. 29 Among all of these kinds of materials, silica xerogels with high specic surface area (500-1500 m 2 g À1 ), pore volume (0.03-0.35 g cm À3 ), high porosity (80-99%) and plenty of silanol groups (Si-OH) distributed on the surface could be promising materials to use as effective adsorbents for radionuclides.…”

Mechanism of calcium hydroxide-reinforced magnesium-loaded clinoptilolite/phosphoric acid-modified biochar for NH3-N removal from rare earth element tailing wastewater

“…16 Modification with zeolite and biochar can increase the adsorption capacity, including alkali and metal ion modifications. 17,18 Wang et al 19 reported that the NH 3 -N removal rate of zeolite modified with 2 mol L −1 MgCl 2 was 2.12 times higher than that of natural zeolite. Ma et al 20 reported that the adsorption capacity of carbon/zeolite composites modified with iron was 1.44 times higher than that of unmodified composites.…”

Use of Zeolite to Reduce the Bioavailability of Heavy Metals in a Contaminated Soil

“…Among these amendments, zeolite (ZL) is a typical mineral modification that has been successfully used to remediate the heavy metals contaminated soils (Borowski and wasag, 2019). Because of its more surface area, high affinity for heavy metals and high alkalinity which enhances the fertility of soil and ultimately improves pH, cation exchange capacity (CEC) and the water holding capacity (WHC) of the soil (Wang et al, 2016).…”