Bench scale feasibility testing is a very powerful tool for the treatment water and wastewater. Due to the fact that not all wastewater characteristics are alike. For example, wastewater from one source may have more organics that can affect its response to the chemical treatment. While different wastewater sources can have its own unique characteristics, the use of feasibility testing can take out the guess work on the type of chemical treatment and physical separation.
Bench feasibility may include but not limited to the following:
- Dissolved air flotation (DAF)
- Thickening (sludge thickening)
- Clarification (conventional and reactor clarification)
- Inclined plate settler
- Filtration (MMF)
- Pressure filtration (plate and frame)
- Vacuum filtration (horizontal, drum, precoat)
Feasibility begins with understanding the treatment objectives and conducted on a representative sample at the process conditions of the plant condition (i.e., pH, temperature, solids concentration, etc.).
The general feasibility test includes:
- Determination of the treatment objectives (set by the plant owner or its representative)
- Sample characterization (i.e., TSS, TDS, TS, pH, alkalinity, temperature, other constituent like metals, organic, nutrients, etc.)
- Chemical selection (i.e., coagulant/flocculant)
- Jar testing to look at the chemical type, dosage, pH, mixing time, and mixing intensity
- Once the chemistry has be selected, physical separation type is selected (i.e., flotation, sedimentation, or dewatering)
- Depending on the stage within the process flow diagram, flotation, sedimentation, or dewatering may be the starting point
- It may be necessary to conduct the pretreatment before the dewatering to gauge the upstream separation performance
The Results
At the end of the feasibly testing, the results will show the value of the capital expenditure (based on sizing), operational expenditure (total connected horsepower based on the size of the equipment, chemical consumptions and complexity of the operation). In addition, the feasibility testing will provide the expected process performance.