By Evan Williams and Randy Bodnar
April 1, 2019
Liquid waste presents a unique challenge and opportunity for landfill owners.
Naturally, many factors get figured into the decision on where to locate a liquid bulking operation at your landfill. These factors get grouped into four categories:
- Business case
- Environmental thoughts
- Future growth
- And operational thoughts
When you understand the pros and cons of locating a solidification operation at your landfill, your decision will help to serve business needs now and in the future.
First determine what makes sense for the business. At this stage, complete a review of needs to determine an opportunity. For example, gather the volumes of incoming materials including liquid, wet waste and solidification agents. Once gathered, an estimate of revenue the operation will generate, becomes available. Contrast the incurred expenses through design, permitting, construction, and ongoing operating costs. When there is a viable business case, proceed to the next steps.
Liquid waste is not allowed in landfills in its original form. Excess moisture is a common concern in landfills. Additionally, most landfill compliance issues relate to excess moisture. Introducing materials that have a high liquid content runs counter to keep material dry. Many liquids cannot be processed at a private or municipal sanitary facility. Or they cannot get processed in another cost-effective manner. That is where liquid bulking/solidification can perform a necessary service.
Testing will need to get completed before liquid/wet wastes are approved for acceptance, solidification, and disposal. Typically, wet wastes are reviewed for hazardous and non-hazardous categorization. As well as, other factors that would make it undesirable for disposals.
Once the wet waste material is acceptable, test mixes get prepared to see what ratios of admixtures and reagents can get used in making an appropriate mix for disposal.
Consideration must be given to resulting moisture content, by asking questions such as:
- Are there no free liquids?
- Can the material be placed and compacted sufficiently?
- Will the mix give up liquids once placed and surcharged by other wastes?
- Are they as strong as the rest of the landfill do will they provide weaker areas/slip planes that could cause failure?
Solidification agent costs directly affect the profitability and success of the operation as well as mixing efforts and transportation of the blended materials to the landfill disposal location.
Bulking: Liquids that are absorbed with a dry solid. Those liquids then release from the mix when they are compressed.
Solidification: The addition of dry material where liquids bind to the reagent and release little or no liquids when compressed.