Phosphorus removal from wastewater by mineral apatite

Natural apatite has emerged as potentially effective for phosphorus (P) removal from wastewater. The retention capacity of apatite is attributed to a lower activation energy barrier required to form hydroxyapatite (HAP) by crystallization. The aim of our study was to test the P removal potential of four apatites found in North America. Minerals were collected from two geologically different formations: sedimentary apatites from Florida and igneous apatites from Quebec. A granular size ranging from 2.5 to 10 mm to prevent clogging in wastewater applications was used. Isotherms (24 and 96h) were drawn after batch tests using the Langmuir model which indicated that sedimentary apatites presented a higher P-affinity (K-L = 0.009 L/g) than igneous apatites (K-L approximate to 0.004L/g). The higher density of igneous material probably explained this difference. P-retention capacities were determined to be around 0.3 mg P/g apatite (24 h). A 30 mg P/L synthetic effluent was fed during 39 days to four lab-scale columns. A mixture of sedimentary material (apatite and limestone 50-50%, w/w) showed a complete P-retention during 15 days which then declined to 65% until the end of the 39 days lab scale test period. A limitation in calcium may have limited nucleation processes. The same mixture used in a field scale test showed 60% P-retention from a secondary effluent (30 mg COD/L, 10 mg Pt/L) during 65 days without clogging. (c) 2006 Elsevier Ltd. All rights reserved.

天然磷灰石已显示出对废水中磷（P）去除具有潜在的有效性。磷灰石的保留能力归因于通过结晶形成羟基磷灰石（HAP）所需的较低活化能垒。我们研究的目的是测试在北美发现的四种磷灰石去除磷的潜力。矿物是从两种地质不同的地层中采集的：来自佛罗里达州的沉积磷灰石和来自魁北克的火成磷灰石。为防止在废水应用中堵塞，使用了粒径在2.5到10毫米之间的颗粒。在使用朗缪尔模型进行批量测试后绘制了等温线（24小时和96小时），结果表明沉积磷灰石比火成磷灰石具有更高的磷亲和力（K - L = 0.009升/克），火成磷灰石的K - L约为0.004升/克。火成物质较高的密度可能解释了这种差异。磷保留能力经测定约为0.3毫克磷/克磷灰石（24小时）。在39天内，将30毫克磷/升的合成废水注入四个实验室规模的柱子中。一种沉积物质（磷灰石和石灰石按50 - 50%，重量比）的混合物在15天内显示出完全的磷保留，然后在39天的实验室规模测试期结束时下降到65%。钙的限制可能限制了成核过程。在现场规模测试中使用的相同混合物在65天内从二级废水（30毫克化学需氧量/升，10毫克总磷/升）中显示出60%的磷保留，且没有堵塞。（c）2006爱思唯尔有限公司。保留所有权利。