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The Problem:
The Southside WWTP in Tyler, TX is a multi-train activated sludge plant, that in recent years (2003-2004) had seen sporadic effluent quality as a result of aeration limitations in the biological processes. These limitations were compounded by low and unstable pH and insufficient influent alkalinity. On top of that, Tyler's recently commissioned water plant occasionally sends low pH solids and process water to the Southside WWTP.
The Result:
Uncontrollable processes leading to intermittent permit limit infringement and a significant potential for permit violations.
Caustic soda was used with limited success to supply much needed alkalinity and raise pH. However, tremendous care was required to prevent pH "spiking" and the amount of alkalinity supplied with these spiking limitations was marginal, at best.
The Answer:
THIOGUARD® TST. The properties of milk of magnesia allowed Tyler personnel the ability to supply significantly more alkalinity in a biologically reactive form, while shifting the pH into a bio-optimal range without the spikes. Additionally, THIOGUARD® added divalent cations, improving the M/D ratio.
The Result:
Once on THIOGUARD®, and through a full activated sludge age cycle, effluent BOD, TSS and NH3 numbers dropped to better than expected (well below permit limits) and remained level. The graphs shown, depict data 6 months prior to the start of THIOGUARD® use, and 6 months with THIOGUARD® use. The City of Tyler has used THIOGUARD® continuously ever since, allowing them to withstand random influent quality swings and aeration system upsets.
As an added bonus:
The improved biological process efficiency led to lower %VS in the biosolids sent to the filter press and a significant reduction in odors emanating from the solids dewatering facility.
AND:
The 12 month period with THIOGUARD® use had 17.5 % fewer solids tons produced and therefore 17.5% lower disposal costs than the 12 month period prior to THIOGUARD® use.
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