## LSU Historical Dissertations and Theses

1997

Dissertation

#### Degree Name

Doctor of Philosophy (PhD)

#### Department

Civil and Environmental Engineering

Ronald F. Malone

Kelly A. Rusch

#### Abstract

Conceptually, the Hydraulically Integrated Serial Turbidostat Algal Reactor (HISTAR) has two components: (1) sealed turbidostats for producing a high quality algal inoculum, and (2) a series of unprotected inter-connected continuous flow stirred tank reactors (CFSTRs) for mass producing algae under approximated plug flow conditions. The hydraulic retention time of each individual CFSTR ($\theta\sb{\rm n})$ is set low enough (dilution is set high) that any suspended organisms (both contaminants and desired algae) entering the CFSTR would be washed to the next CFSTR well within their doubling time. However, as the turbidostats are employed to inoculate the first CFSTR on an almost continuous basis, the desired algae in the CFSTRs would quickly reach steady state densities. Various mathematical and computer models were developed to predict both the algal growth and contaminant washout trends in the series of CFSTRs. A microcomputer, along with the necessary software and hardware components, was used for process control, routine monitoring and data acquisition in the HISTAR system. During the first phase of experimentation, the production from the HISTAR system was evaluated. Results from the production studies indicated that the volumetric production ranged between 46.46 ($\pm$ 7.85)-66.84 $\pm$ 27.03) gms-dry (m$\sp3$ day)$\sp{-1}$ for the turbidostats, and 40.92 ($\pm$ 13.53)-59.52 ($\pm$21.78) gms-dry (m$\sp3$ day)$\sp{-1}$ for the series of CFSTRs. During the second phase of testing, a set of experiments was conducted to practically test the contaminant washout in the series of CFSTRs. Results from the washout experiments clearly demonstrated that the hydraulic retention time in each individual CFSTR ($\theta\sb{\rm n})$ plays the key role in the contaminant mitigation process. The robustness and washout capabilities of the CFSTRs were demonstrated when the CFSTRs, that succumbed to the wrath of more than 300 million live (and multiplying) rotifers in the CFSTRs at a 36 hour individual HRT ($\theta\sb{\rm n}),$ were completely revived by simply adopting a faster flow rate (6 hr HRT). Results from the algal contaminant washout studies demonstrated that the algal contaminants, including ones with growth rates higher than the desired algal growth rates, can be effectively washed out without affecting the desired algal densities.

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