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Analysis of grease abatement devices and the measurement of fat, oil, and grease in food service establishment waste streams.

机译：分析减脂装置，并测量餐饮服务场所废物流中的油脂，油脂。

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摘要

The release of fat, oil, and grease (FOG) into collection systems ultimately results in the blockage of pipes and subsequent sanitary sewer overflows (SSOs). SSOs are a risk to public health and the environment as they release untreated sewage laden with high nutrient and pathogen loading. Currently, municipalities who are responsible for maintaining these collection systems have little guidance as there is a substantial lack of scientifically-based information regarding the effective abatement and measurement of FOG. This research aims to examine the performance of grease abatement devices and to investigate the measurement of FOG in food-laden waste streams.;Grease abatement devices (GAD) are commonly large, below ground tanks that are designed for adequate hydraulic retention time (HRT) to provide separation of light FOG material from influent wastewater. Common designs for GAD utilize dual compartments and are sized for approximately 30 min HRT. However, results of this research indicated highly intermittent systems with the vast majority experiencing HRTs far greater than design. Average HRT for most GADs was greater than 2 hrs with peak discharges 3--7 times the average flow rate. Chemical characterization of GADs indicated the presence of anaerobic microbial activity. Spatial and temporal observation of FOG and food solids profiles in a field GAD indicated what appeared to be the channeling of food solids into the second compartment for commonly used configurations. Implementation of a distributive inlet displayed an elimination of this channeling effect and significant reduction in second compartment food solid accumulation.;Lab-scale and computational fluid dynamics (CFD) modeling of GADs was performed to evaluate a commonly observed submerged inlet pipe configurations and develop design improvements to enhance FOG removal efficiency. Lab-scale results indicated that enhanced FOG removal performance was obtained by tripling the HRT from 20 minutes to 1 hr, however, performance values close to the performance of the 1 hr HRT were obtained with a 20 minute HRT by modifying the internal configuration. As hypothesized from observations of the field GADs, it is believed that the use of distributive inlet configurations may act to reduce short-circuiting effects in GADs. Results indicated lab-scale GAD improvement through the use of distributive configurations. The removal of the baffle wall was also explored in the present study. When the wall was removed with a shortened submerged pipe, GAD performance improved from the standard configuration. When an inverted-inlet tee was used without compartmentalization, however, lab-scale results indicated a poorer performance than the standard configuration.;Investigation into CFD simulations of GAD configurations followed performance trends established in the lab-scale experiments except in conditions featuring the inverted tee inlet. It is hypothesized that the exclusion of droplet coalescence and breakup in the CFD simulation resulted in these discrepancies.;Preliminary analysis of FOG concentration form independent commercial laboratories indicated high variability and under-recovery of known concentrations. For this reasons, an investigation into the n-hexane liquid-liquid extraction of FOG from water was undertaken. Observation of edible- FOG recovery in the presence of synthetic food-laden waste streams indicated substantial interference in the presence of wheat flour and whey proteins. Other comparisons with sucrose, corn starch, and a surrogate fiber indicated no interference with FOG recovery. LLE of various free-fatty acids and FOG types of varying saturation levels indicated no significant difference in recovery performance. Investigation of an EPA defined standard material (hexadecane) indicated that the volatile nature of the compound lead to substantially poorer recovery than food-based standards that did not volatilize at all during testing. FOG sample measurement with n-hexane was not able to recover 100% of the FOG material during testing. Further investigation into this occurrence suggests the persistent adhesion of samples to lab glassware.
机译：油脂，油脂（FOG）释放到收集系统中最终导致管道堵塞和随后的下水道卫生溢流（SSO）。 SSO释放未经处理的，营养和病原体含量高的污水，对公共健康和环境构成威胁。当前，负责维护这些收集系统的市政当局几乎没有指导，因为关于有效减少和测量FOG的科学信息非常缺乏。这项研究旨在检查油脂去除设备的性能并研究含食物的废物流中FOG的测量。油脂去除设备（GAD）通常较大，设计用于足够的水力停留时间（HRT）的地下储罐从进水中分离出轻质FOG材料。 GAD的常见设计采用双隔室，其尺寸约为HRT 30分钟。然而，这项研究的结果表明高度间歇性的系统，绝大多数的HRT远远超过设计。大多数GAD的平均HRT大于2小时，峰值流量是平均流速的3--7倍。 GAD的化学表征表明厌氧微生物活性的存在。在现场GAD中对FOG和食物固形物轮廓进行时空观察表明，对于通常使用的配置，似乎是食物固形物进入第二隔室的通道。分配入口的实现显示消除了这种窜流效应，并大大减少了第二部分食品中的固体积累。GAD的实验室规模和计算流体动力学（CFD）建模进行了评估，以评估通常观察到的浸入式入口管道的配置并进行设计改进以提高FOG去除效率。实验室规模的结果表明，通过将HRT从20分钟增加三倍到1小时可以提高FOG去除性能，但是，通过修改内部配置，使用20分钟的HRT可以获得接近1小时HRT性能的性能值。根据对现场GAD的观察假设，可以相信使用分布式进气口配置可以减少GAD中的短路效应。结果表明，通过使用分布式配置，实验室规模的GAD得到了改善。在本研究中还研究了去除挡板壁的方法。当用缩短的浸没管拆除墙壁时，GAD性能比标准配置有所提高。但是，当使用不带隔段的倒装三通时，实验室规模的结果表明，其性能比标准配置差。; GAD配置的CFD模拟研究遵循了实验室规模实验中确定的性能趋势，但条件是具有倒置的条件三通入口。假设在CFD模拟中排除液滴聚结和破裂会导致这些差异。单独的商业实验室对FOG浓度的初步分析表明，已知浓度的变异性高且回收率低。因此，对从水中正己烷液-液萃取FOG进行了研究。在载有合成食品的废物流的情况下观察到可食用的FOG回收率表明，小麦粉和乳清蛋白的存在会产生重大干扰。与蔗糖，玉米淀粉和替代纤维的其他比较表明，对FOG的回收没有干扰。各种游离脂肪酸的LLE和饱和度不同的FOG类型均表明回收性能无显着差异。对EPA定义的标准材料（十六烷）的研究表明，该化合物的挥发性导致其回收率远低于食品标准，而食品标准在测试过程中根本不会挥发。在测试过程中，使用正己烷进行的FOG样品测量无法回收100％的FOG材料。对这种情况的进一步调查表明，样品对实验室玻璃器皿的持久粘附力。

著录项

  • 作者

    Aziz, Tarek N.;

  • 作者单位

    North Carolina State University.;

  • 授予单位 North Carolina State University.;
  • 学科 Engineering Civil.;Engineering Sanitary and Municipal.;Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 289 p.
  • 总页数 289
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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