Abstract

Abstract Beneficial reuse and appropriate disposal of water treatment residuals (WTRs) are of great concern for sustainable drinking water treatment. Using WTRs to remove phosphorus (P) is widely regarded as a feasible approach. However, the information is still limited on air-dried WTRs containing polyaluminium chloride (PAC) and anionic polyacrylamide (APAM) used to adsorb P. The objectives of this study were to construct artificial neural network (ANN) models for P adsorption onto WTRs from distilled de-ionized (DDI) water solution and stormwater, to investigate the performance of ANN in predicting phosphorous adsorption, and to model isotherm adsorption, kinetics, and thermodynamics by using the index of model performance. Batch experiments were performed with different WTRs dosage, pH, initial P concentration, temperature, and time. ANN models accurately predicted the P concentration at equilibrium. Non-linearized Langmuir model fitted the isotherm data best. Pseudo second-order kinetic model provided a better fit to experimental data. The adsorption process may be at least simultaneously controlled by surface adsorption and intraparticle diffusion. The P adsorption is a homogenous monolayer adsorption that is spontaneous, endothermic, and entropy production process. WTRs were found to be favorable and effective in removing P, but the P removals had significant differences in both solutions.

Highlights

  • Water treatment residuals (WTRs), named waterworks sludge (Al-Tahmazi & Babatunde ) or water treatment plants sludges (Krishna et al ), are waste by-products produced during drinking water treatment from most of the municipalities in the world

  • This study demonstrates that air-dried water treatment residuals (WTRs) containing polyaluminium chloride (PAC) and anionic polyacrylamide (APAM) from sludge dewatering units of a typical water treatment facility, a type of WTRs found world-wide and recently available, can be effectively reused as a potential alternative part of traditional soil-based media or substrate in stormwater bioretention systems for P removal from stormwater runoff

  • (5) Air-dried WTRs containing PAC and APAM were found to be effective in removing P from distilled de-ionized (DDI) water solution and stormwater, but the P removals at equilibrium had significant differences

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Summary

Introduction

Water treatment residuals (WTRs), named waterworks sludge (Al-Tahmazi & Babatunde ) or water treatment plants sludges (Krishna et al ), are waste by-products produced during drinking water treatment from most of the municipalities in the world. The reuse and appropriate disposal of WTRs are of great concern for sustainable drinking water treatment. The amount of WTRs produced from the expansions of the global drinking water treatment facilities is increasing rapidly. In 2014, the amount of dewatered WTRs produced was 22,000,000 metric tons B. Fedler | Modeling P adsorption onto PAC water treatment residuals

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