Abstract

High amounts of phosphate discharged in receiving water can lead to eutrophication. Once a water body is enriched with phosphate, it can prompt the growth of plants and cause algal blooms. The water body may also lose its important functions and cause adverse effects on the environment and human health. In this study, removal of phosphate from domestic wastewater treatment plant effluent was elucidated using iron-coated waste mussel shell. The phosphate adsorption by iron-coated waste mussel shell was examined with respect to initial phosphateconcentration (7 mg L^–1), solution volume (0.2 L), adsorbent dosage (4–20 g), and contact time (1–5 day). The chemical composition of iron-coated waste mussel shell was analyzed using energy dispersive X-ray fluorescence spectrometer. The measurement of the specific surface area of iron-coated waste mussel shell was performed by multiple-point method according to the Brunauer, Emmett, and Teller theory. Several kinetic models (i.e., pseudo-first order and pseudo-second order) and isotherm models (i.e., Freundlich and Langmuir) were used to describe the adsorption behavior. The optimum removal efficiency of phosphate can reach at 95.7% after 120 h with the amount of iron-coated waste mussel shell used to run the experiment was 20 g and the treated effluent phosphate concentration of 0.3 mg L^–1, was verified. Experimental data can be well described by pseudo-second order kinetic model (R² > 0.99) and Freundlich isotherm model (R² = 0.93), suggesting that chemisorption and multilayer adsorption occurred. Furthermore, a two-stage batch system was proposed to assess the optimum adsorbent dosage for phosphate removal. The two-stage system has contributed to reduce iron-coated waste mussel shell dosage by 56.94%, as compared to one-stage and thus reduced the operating cost of iron-coated waste mussel shell.

中文翻译：

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铁包废贻贝壳去除废水中磷酸盐的两阶段批处理系统以评估最佳吸附剂用量

摘要

接收水中排放的大量磷酸盐会导致富营养化。一旦水体富含磷酸盐，它就会促进植物的生长并导致藻类大量繁殖。水体也可能失去其重要功能，对环境和人类健康造成不利影响。在这项研究中，使用铁包覆的废贻贝壳阐明了从生活污水处理厂流出物中去除磷酸盐的方法。研究了铁包覆的废贻贝壳对磷酸盐的吸附与初始磷酸盐浓度 (7 mg L ^–1)、溶液体积 (0.2 L)、吸附剂用量 (4–20 g) 和接触时间 (1–5 天)。采用能量色散X射线荧光光谱仪分析了铁包覆废贻贝壳的化学成分。根据Brunauer、Emmett和Teller理论，采用多点法测量铁包覆废贻贝壳的比表面积。几种动力学模型（即准一级和准二级）和等温线模型（即Freundlich 和Langmuir）用于描述吸附行为。^{实验所用铁包蚌壳用量为20 g，处理后出水磷酸盐浓度为0.3 mg·L -1}，120 h后磷酸盐的最佳去除率可达95.7%，经过验证。准二级动力学模型（R ² > 0.99）和Freundlich等温线模型（R ² = 0.93）可以很好地描述实验数据，表明发生了化学吸附和多层吸附。此外，提出了一个两阶段间歇系统来评估去除磷酸盐的最佳吸附剂用量。与一级系统相比，两级系统有助于减少铁包衣废贻贝壳用量56.94%，从而降低了铁包衣废贻贝壳的运营成本。