Abstract This study proposed that hybrid scrap cast iron particles (SIP)-aerobic biodegradation technology could enhance the biodegradability of toxic wastewater. SIP cleaved the azo linkages of Direct Green1 dye to form benzidine, 4-aminophenol, aniline and 1,2,7-triamino-8-hydroxynapthalene-3,6-disulfonic acid. SIP-mediated dye reduction was effective at wide pH range; however, kinetic analysis revealed fastest pseudo-first order dye reduction rate at acidic pH 3 ( k d = 0.549 min −1 ) followed by pH 9 ( k d = 0.383 min −1 ) and pH 7 ( k d = 0.318 min −1 ). The daughter aromatic amines produced were partially adsorbed onto the SIP surface and maximally at neutral pH. The adsorption process followed pseudo-second order adsorption kinetics and Langmuir isotherm. Benzidine was adsorbed more than 4-aminophenol and aniline. BOD 5 of the SIP-treated effluent increased from 0.93 to 12 mg/L showing improved biodegradability. The daughter amines were rapidly mineralized in the aerobic bioreactor within 6 h. Cost-effective SIP pre-treatment could accelerate mineralization and detoxification of recalcitrant wastewater.

中文翻译：

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用于联苯胺基偶氮染料废水完全矿化的有效废铁颗粒 (SIP) 预处理

摘要 本研究提出混合废铸铁颗粒（SIP）-好氧生物降解技术可以提高有毒废水的生物降解能力。SIP 裂解 Direct Green1 染料的偶氮键，形成联苯胺、4-氨基苯酚、苯胺和 1,2,7-triamino-8-hydroxynapthalene-3,6-disulfonic acid。SIP 介导的染料还原在较宽的 pH 范围内有效；然而，动力学分析表明，在酸性 pH 3 (kd = 0.549 min -1 ) 和 pH 9 ( kd = 0.383 min -1 ) 和 pH 7 ( kd = 0.318 min -1 ) 下，伪一级染料还原速率最快。产生的子代芳香胺部分吸附在 SIP 表面上，在中性 pH 下最大。吸附过程遵循准二级吸附动力学和朗缪尔等温线。联苯胺多被4-氨基苯酚和苯胺吸附。SIP 处理出水的 BOD 5 从 0.93 增加到 12 mg/L，表明生物降解性得到改善。子胺在好氧生物反应器中在 6 小时内迅速矿化。具有成本效益的 SIP 预处理可以加速难降解废水的矿化和解毒。