Ammonium Release and Adsorption Characters of Polyurethane-Biochar Crosslinked Material as an Additive Filler in Stormwater Treatment.

Yuan Wang,Chuanyue Wang,Bao Wang,Yike Meng

doi:10.3390/polym13101557

Abstract

The additive fillers in bioretention facilities play a leading role in stormwater treatment to purify polluted runoff. At present, many traditional materials could not meet the requirements at the same time, including low ammonium leaching quantities, high water storage volume and strong ammonium adsorption. This study investigated a polymer material, polyurethane–biochar crosslinked material (PCB), to evaluate the feasibility of using it as an additive filler in stormwater treatment compared with its raw material hardwood biochar (HB), and two traditional fillers. Successive leaching and ammonium isothermal adsorption experiments were conducted in deionized water and artificial stormwater. PCB leached 4.98–5.31 μmol/g NH4-N, less than the leaching quantities of compost, the traditional filler. After polyurethane modification, ammonium adsorption of PCB was improved: at a typical ammonium concentration of 2 mg/L in stormwater, PCB could adsorb 43.6 mg/kg ammonium versus 34.6 mg/kg for HB. With the addition of PCB in sand column, the ammonium adsorption improved from 31.34 to 84.72%. To improve the performance of bioretention facilities, PCB is recommended to be added into filter layers in stormwater treatment, taking advantage of its high cation exchange capacity and spongy internal structure to minimize overland flooding and enhance removal of ammonium from stormwater.

Highlights

The rapid development of urbanization brings convenience, and brings ecological problems that break the balance of the water resource cycle [1]
As an additive filler in bioretention facilities, PCB had outstanding physical properties in stormwater treatment compared to other materials for its lightness, porosity and hydraulic performance
Additive fillers in the filtration layers are the key to improve the capacity of pollutants removal and permeability in bioretention systems

Summary

Introduction

The rapid development of urbanization brings convenience, and brings ecological problems that break the balance of the water resource cycle [1]. The balance of the water resource cycle is fundamental to sustain human development, as it realizes the migration and transformation of water, energy and geochemical substances in the earth system [2]. Human activities in urban areas aggravates the non-point source pollution of water resources, especially ammonium pollution [3]. Bioretention systems are designed to address the imbalance of the water cycle and stormwater runoff pollution [6]. They can remove dissolved pollutants from stormwater runoff and reduce the peak volume of runoff [7]

Methods

Results

Conclusion