脱水与凝固

案例研究

Liquid waste is generated from all types of processes and operations, and although there are many different technologies and techniques to treat and manage liquid waste, the basic principles are similar, which is to either separate the solids from the liquid or to turn the liquid waste into a solid material by adding an amendment or drying.

“Liquid landfills” do not exist, which means that any liquid waste must be processed and treated. Traditional liquid waste dewatering methods typically involve filters, presses, and centrifuges to separate the solids from the liquid, where the liquid component is discharged or reused, while the solids component is trucked off for disposal.

An alternative treatment approach is solidification, where an amendment or reagent is added directly into the liquid waste which causes the liquid waste to turn into a solid material through the principles of absorption or adsorption.

Although dewatering and solidification are sometimes seen as competitive processes, they should instead be considered as complimentary, as their target waste streams have some significantly different characteristics.

Dewatering methods are typically costlier as they require expensive capital equipment which also have high operating costs; however, they work well on low solids waste streams, such as wastewater, to remove large amounts of free liquid and obtain a higher solids sludge. Solidification methods are typically easier to apply and do not require an expensive capital investment in processing equipment; however, they should really be applied to high solids waste streams, which may be a thick liquid or semi-solids. Solidification can also be used to “polish” off the solids separated from dewatering processes. It is very common for dewatering to produce a semi-solid sludge that will fail slump or paint filter regulatory solids test criteria and may require a small amount of an amendment to meet this requirement.

From the solidification point of view, it is beneficial to remove any free liquid from the waste stream before adding solidification reagents, as this will lower the reagent dosage and result in a drier, crumbly material. Simple dewatering methods, such as gravity settling, may be used to remove free water, and the remaining, higher solids content, sludge may be easily solidified.

From the dewatering point of view, it is often very easy to remove the initial portion of free water, but a significant amount of energy is required to remove “bound” water in the liquid waste stream. Therefore, utilizing solidification methods as a polishing step at the end may prove to be more beneficial and cost effective compared to using dewatering equipment to achieve a dry material.

In summary, liquid waste treatment is an innovative and growing industry. We have an opportunity to pull our resources together and use multiple technologies to achieve the common goal. Dewatering and solidification both excel in different aspects, and we should exploit these methodologies for synergies and utilize them where most appropriate.

卡博内郡世界自然基金会泻湖

主要利益相关者:

业主 淡水河谷加拿大有限公司
承包商: Tervita 公司
经销商: Di-Corp

VALE-tervita-di-corp

挑战

淡水河谷公司在加拿大安大略省北部拥有并经营着一个采矿场。通过采矿和精炼活动,他们产生了一种污泥废物副产品。客户需要一个高效的挖掘和运输解决方案,将这些污泥运到场外的垃圾填埋场。

日期

2018 年 9 月底 - 2018 年 10 月中旬

解决方案

在竞标过程中,MetaFLO 参与提供了最佳的混合料和加料率,以达到污泥挖掘和运输所需的固体标准。MetaFLO 利用分析数据估算出的剂量率为 1.1%(按重量计)(基于高含水量)。建议使用大型搅拌桶,以增加表面接触,提高桶搅拌过程的效率。目前尚未获得样本。

结果

Tervita 公司利用 MetaFLO 试剂固化了约 4,000 立方米的污泥。现场有两个 35 立方米的垃圾箱,装载着 "较重 "和 "较轻 "的污泥。最初估计的用量是准确的,因为实际处理平均每立方米污泥大约需要 30 磅 MetaFLO MF006 试剂。所有材料都被安全地运往淡水河谷的场外垃圾填埋场。工作按时完成。