Date of Award

Summer 1998

Document Type

Thesis

Degree Name

Master of Science in Environmental Engineering - (M.S.)

Department

Civil and Environmental Engineering

First Advisor

Dorairaja Raghu

Second Advisor

C.T. Thomas Hsu

Third Advisor

Sudhi Mukherjee

Abstract

Disposal of water treatment plant (WTP) residuals has always been an important consideration for the water industry. Stringent water quality standards, environmental regulations, and unavailability of land for ultimate disposal affect disposal of large amounts of this residual. The search for alternate economical disposal options and beneficial use are probably the next most logical and economical step to take.

This study was performed to explore the possibility of stabilization of water treatment plant (WTP) residuals using additives. Three water treatment plant (WTP) residuals from treatment plants in New Jersey were used for the analysis. The objective of this research is to, if possible, present an acceptable application such as engineering fill for this stabilized product. The investigation was divided into three phases:

  1. Study the geotechnical characteristics of the WTP residuals
  2. Review possible disposal options of WTP residuals and investigate use of WTP residuals in brickmaking
  3. Develop and test of Sorbond® stabilized WTP residuals.

In the first phase of this study, the WTP residuals were characterized and the geotechnical properties evaluated. This was done to understand and differentiate between the types of WTP residuals being tested. In the second phase, attempts were made to replicate and formulate a procedure to successfully manufacture quality residual-amended bricks. WTP residuals were mixed with various additives such as fly ash, kiln dust, shale etc to manufacture bricks. This effort failed to produce promising results, as the author was unable to develop a proper manufacturing process under the laboratory setup. The residual amended brick molds from the kiln were soft and showed numerous cracks throughout the body. Thus further testing on the brick molds could not be carried out.

The third phase dealt with mixing different types of Sorbond® with WTP residuals. Unconfined compressive strength, compaction tests and durability tests were conducted on the final cured samples. The results were compared with the properties of WTP residuals to illuminate the change, if any, in the properties.

The results indicate that the residual-sorbond® mix showed better strength values as compared to the WTP residuals. Also the freeze-thaw and wet-dry durability characteristics of the residual-sorbond mix was greatly enhanced to qualify the product for engineering applications. A proportion of sorbond®, as low as 10% by dry weight, mixed with WTP residual can be compacted in the field provided the mix was allowed to dry for two days.

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