College of Agricultural Engineering, Campinas State University, São Paulo, Brazil.
Department of Agricultural Engineering, Federal University of Viçosa, Minas Gerais, Brazil.
Environ Technol. 2022 Jan;43(2):237-254. doi: 10.1080/09593330.2020.1783372. Epub 2020 Jun 26.
Dairy operations generate large volumes of polluted wastewater that require treatment prior to discharge. Chemically enhanced primary treatment (CEPT) is a widely utilized wastewater treatment strategy; but it requires the use of non-biodegradable coagulants that can lead to toxic-byproducts. In this study, chitin from shrimp shell waste is extracted and converted into chitosan. Chitosan was demonstrated to be a natural, low-cost alternative coagulant compatible with the CEPT. Following treatment, dissolved air flotation allowed for the removal of turbidity, COD, and UV from the synthetic dairy effluent (SDE). Doehlert matrix was used to optimize the chitosan dosage and pH of the CEPT; as well as to model the process. The mechanisms behind the coagulation-flocculation were revealed using zeta potential analysis. FTIR spectroscopy was utilized to confirm the functional groups present on the chitosan. Chitosan with a degree of deacetylation equal to 81% was obtained. A chitosan dose of 73.34 mg/L at pH 5.00 was found to be optimal for the removal of pollutants. Removals of COD, turbidity and UV were 77.5%, 97.6%, and 88.8%, respectively. The amount of dry sludge generated to treat 1 m³ of SDE was 0.041 kg. Coagulation-flocculation mechanisms involved in chitosan-mediated treatment of SDE involve the neutralization of electrostatic charges carried on the amine groups present in cationic chitosan at pH 5.00. Doehlert matrix proved to be a useful tool in optimizing parameters throughout the coagulation-flocculation process. Chitosan from shrimp waste is a low-cost, eco-friendly coagulant alternative for the removal pollutants from dairy effluent using the CEPT.
奶制品加工会产生大量受污染的废水，这些废水在排放前需要进行处理。强化一级处理（CEPT）是一种广泛应用的废水处理策略；但它需要使用不可生物降解的混凝剂，这些混凝剂可能会产生有毒副产物。在这项研究中，从虾壳废物中提取并转化为壳聚糖。壳聚糖被证明是一种天然的、低成本的替代品混凝剂，与CEPT 兼容。经过处理后，溶气浮选可去除合成乳废水（SDE）中的浊度、COD 和 UV。Doehlert 矩阵用于优化 CEPT 中的壳聚糖剂量和 pH 值；并对该过程进行建模。通过zeta 电位分析揭示了混凝-絮凝的机制。傅里叶变换红外光谱（FTIR）用于确认壳聚糖上存在的官能团。得到脱乙酰度为 81%的壳聚糖。在 pH 值为 5.00 时，壳聚糖剂量为 73.34 mg/L 被发现是去除污染物的最佳条件。COD、浊度和 UV 的去除率分别为 77.5%、97.6%和 88.8%。处理 1 立方米 SDE 产生的干污泥量为 0.041 千克。壳聚糖介导的 SDE 处理涉及的混凝-絮凝机制包括在 pH 值为 5.00 时，带正电荷的壳聚糖中的胺基所携带的静电荷中和。Doehlert 矩阵被证明是优化整个混凝-絮凝过程参数的有用工具。虾壳废物中的壳聚糖是一种低成本、环保的混凝剂替代品，可用于使用 CEPT 去除乳废水的污染物。
