Phosphate Removal from Secondary Effluents Using Coal Gangue Loaded with Zirconium Oxide

Jibing Xiong,Zhenli He,Qaisar Mahmood,Jianfeng Zha,Li Zang

doi:10.3390/su11092453

Abstract

Phosphorus from secondary effluents and coal gangue from coal mining have caused serious environmental problems. The feasibility of phosphate removal from secondary effluents using calcinated coal gangue loaded with zirconium oxide (CCG-Zr) was explored. Major influencing factors like the calcinated temperature, CCG-Zr ratio, adsorbent dose, time and solution pH, etc. were investigated. Newly developed CCG-Zr accomplished a significantly higher phosphate removal for phosphate (93%) compared with CCG (35%) at a calcinated temperature of 600 °C and CCG-Zr mass ratio of 1:1. For CCG-Zr the maximum phosphate removal rate (93%) was noted at an initial phosphate concentration of 2 mg/L within 20 min. The CCG-Zr displayed a higher phosphate removal rate (85–98%) over a wide range of solution pH (2.5~8.5). The adsorption isotherms fitted better to the Freundlich (R2 = 0.975) than the Langmuir model (R2 = 0.967). The maximum phosphate adsorption capacity of the CCG-Zr was 8.55 mg/g. These results suggested that the CCG-Zr could potentially be applied for the phosphate removal from secondary effluents.

Highlights

Phosphorus is a limiting nutrient for algal growth and its excessive concentration in wastewater discharged into aquatic environments often causes serious eutrophication problems, namely harmful algal blooms, depletion of dissolved oxygen and decline of aquatic life, etc. [1,2]
The XRD patterns of calcinated coal gangue loaded with zirconium oxide (CCG-Zr) under different calcinated temperatures were illustrated in Figure 1, The major crystalline phase of Calcinated coal gangue (CCG)-Zr under different temperatures contained α-SiO2, Gismondine and ZrO2
XRD of CCG-Zr at 300 ◦C only showed two weak peaks at 50◦ and 60◦, respectively. It indicated that ZrO2 began to appear in an orthorhombic state [26], it was not well crystallized at 300 ◦C calcination which was supported by the low number and intensity of the orthorhombic ZrO2 XRD peak in CCG-Zr at 300 ◦C

Summary

Introduction

Phosphorus is a limiting nutrient for algal growth and its excessive concentration in wastewater discharged into aquatic environments often causes serious eutrophication problems, namely harmful algal blooms, depletion of dissolved oxygen and decline of aquatic life, etc. [1,2]. Phosphorus is a limiting nutrient for algal growth and its excessive concentration in wastewater discharged into aquatic environments often causes serious eutrophication problems, namely harmful algal blooms, depletion of dissolved oxygen and decline of aquatic life, etc. The secondary effluents from a typical sewage treatment plant may contain 1.0–2.0 mg/L Phosphorus in an anaerobic-anoxic-oxic (A2/O) process [3], which contributes to eutrophication in the receiving water bodies [4]. Phosphate needs to be removed from secondary effluents to control eutrophication of the receiving water bodies. The control of phosphate in secondary effluents has been widely investigated. Great attention has been paid to the utilization of industrial wastes or their modification for phosphate removal. The major advantages of using these wastes or their modifications for wastewater treatment are cost effectiveness and desired reuse

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