- Industrial WWTP Upgrade Engineering Evaluation
Burns & McDonnell performed a waste characterization and an engineering evaluation of the 1.2 million-gallon-per-day (MGD) Industrial Wastewater Treatment Plant (IWTP) for a confidential client, which operates the Department of the Army's Lake City Army Ammunition Plant in Independence, Mo. The evaluation included a wastewater characterization, treatability testing, effluent permit negotiations and an engineering evaluation. The industrial wastewater generated from the ammunition plant is discharged into the on-site IWTP, where it is treated before discharge to the sanitary sewer. The IWTP consists of grit chambers, equalization basins, flocculators, dissolved air flotation units, first stage gravity filters, solids contact clarifiers, tertiary gravity filters, and final pH adjustment basin. The waste characterization was performed in one week and included: hourly composite samples; hourly total influent flow measurements; 24-hour influent and effluent composite samples for the primary unit treatment processes; and total plant effluent flow records to evaluate the effectiveness of metal removals, total suspended solids, and oil and grease.
The engineering evaluation included selection of potential treatment process improvements to meet new stringent effluent limits for heavy metals and oil and grease. Based on the results of the evaluation, laboratory experimental studies were conducted to determine if the selected treatment process upgrades could meet the new, proposed effluent limitations. Treatment processes selected for testing included microfiltration, chelating ion exchange polishing, and sulfide treatment for metals removal along with clay-based media for oil and grease polishing. Laboratory testing also was completed to determine the impact on sludge generation and sludge settlability from replacing hydrated lime neutralization with sodium hydroxide neutralization. The results of the testing indicated that none of the selected treatment processes was capable of meeting the new treatment limits and that replacing lime with sodium hydroxide was not significantly more cost-effective.
- Wastewater characterization
- Treatability studies
- Effluent permit negotiations
- Evaluation of existing system
- Process evaluation
- Recommended upgrades
- Construction cost opinion
- O&M cost opinion
Because of the low proposed discharge limitations for metals, negotiations were conducted with the U.S. Environmental Protection Agency to develop a revised basis from which to develop the new discharge limitations. A review of the industrial processes that discharge wastewater to the IWTP indicated that many of the processes were incorrectly classified under the Copper Forming Federal Category. Since the Copper Forming Category uses mass based limits, the resulting proposed effluent limits for the IWTP discharge were unreasonably low. However, the review of the manufacturing processes discharging to the IWTP also indicated that many of the processes instead should be classified under the Metal Finishing Category. As a result of the manufacturing process review, a report was developed that presented the basis for the recategorization of the manufacturing processes for submission to the EPA to allow the new, proposed discharge permit limits to be similar to the current discharge permit limits.
An engineering evaluation developed these recommendations for upgrades to meet a future flow of 1.4 MGD and to meet the negotiated effluent permit limits:
- Additional equalization capacity — 13 hrs of detention
- Lime reactor — two 31,500 gallon reactors with mixing
- Parallel plate clarifiers — two 1,940-square-foot clarifiers with sludge pumping
- Stabilization tanks — two 14,000 gallon tanks with mixing
- Solids contact clarifiers — two 54-foot diameter units
- Final gravity filters — two, 64-square-foot each
- Lime feed system modifications
- Building additions and road improvements
- Utility demolitions and relocations