COLUMBIA

Columbia determined that a system upgrade was necessary because (1) the population served and the related daily flow rates were increasing substantially from approximately 0.65 mgd to 1.47 mgd and Columbia WTTP was reclassified to a major facility (2) discharge permit requirements for treatment were becoming more stringent from Total Suspended Solids (“TSS”) at discharge of 25 mg/l (from 45 mg/l) and Biochemical Oxygen Demand (“BOD”) at discharge of 20 mg/l (from 37 mg/l) and (3) Columbia was not consistently meeting discharge requirements.

Without changed practices, compliance by Columbia with the even more stringent standards from Illinois EPA, at more than twice the daily flow rate, was regarded as improbable.

The principal problem areas were determined to be:

• Ineffective oxygen delivery by mechanical surface aerators as evidenced by supersaturation of oxygen on the surface and low or no dissolved oxygen at the bottom of the lagoon.

• Substantial accumulation of organic sludge, particularly in the primary and secondary treatment cells.

• Inadequate treatment in their 8,000 ton rock filter/tertiary cell which was principally a rock filter. (Columbia installed a rock filter field in 1986 as required by ILEPA. It was plugged and non-functional within a year of initial operations. Columbia by passed the rock filter field with a six-foot wide channel to allow discharge of effluent and continued operations. Accordingly, very little if any nitrification (ammonia removal) and TSS removal was occurring in the final or tertiary stage of the Columbia system as evidenced by progressively increasing ammonia, BOD, phosphorus and TSS values.)

• Significant surface algae problems in warm weather conditions.

Columbia and its design engineer Horner and Shifrin were impressed with the performance history of ADS and the predicted capability of AMTS to provide solid year round performance (even with the cold climate conditions of Illinois winters) and to substantially reduce the high cost associated with periodic sludge disposal. Briefly, AMTS provides the quality treatment of mechanical plants in lagoons at significant savings in capital and operating costs. The AMTS process combines ADS’s proprietary diffusion aeration products, engineered surface area (“AquaMats®”) and bioaugmentation (“Bacta-Pur®”) technologies to form a very stable, and low-maintenance integrated system for natural microbial treatment of municipal wastewater. Operational costs are typically very low. Because of the efficiency of AMTS, sludge handling is not necessary for up to 10 years or longer.

DESCRIPTION OF AMTS UPGRADE:

System Wide: Installation of ADS fine-bubble aeration in the primary, secondary and tertiary cells to provide required oxygen transfer rates throughout the water column of the lagoon to replace mechanical surface aerators. Three blowers (rated at 50 HP each—two operational, one standby) were installed to provide the required air for oxygen transfer and circulation.

Primary and Secondary Treatment Cells: Supplemental bioaugmentation with sludge digesting bacteria using certified non-pathogenic and non-GMO strains of beneficial microbes from BactaPur® for organic digestion of accumulated sludge and influent organics.

Tertiary Treatment Cell: Installation of rows of AquaMats® for Biofiltration to provide surface area for biological reduction of TSS, BOD5, Phosphorus and to also enhance nitrification along with supplemental bioaugmentation with nitrifying bacteria using certified non-pathogenic and non-GMO strains of beneficial microbes from BactaPur®. ILEPA approved the AquaMats® for Biofiltration as a replacement for the previous rock filter tertiary treatment system that had not functioned effectively at Columbia.
AMTS COSTS---CAPITAL, OPERATING AND MAINTENANCE:

Capital costs incurred by the City of Columbia for the AMTS upgrade were approximately $987,000. This cost is projected to be recaptured through the higher volumes processed by the plant and an increase in sanitary sewer hookup fees for new customers. Operating and Maintenance costs (principally labor and electrical use charges) for AMTS have not increased as compared to the surface aerator system that AMTS replaced, despite the increased system capacity and improved treatment. To date, Columbia has lowered its operating costs because the AMTS system is sufficiently effective in reducing Fecal coliform levels so that routine chlorination and dechlorination is not necessary. Elimination of the routine chlorination also has important environmental stewardship benefits and reduces the risk to plant personnel that is inherent in handling liquid or gaseous chlorine.