The City of Boynton Beach wanted to make chemical changes at the city’s West Water Treatment Plant (WTP) for two reasons: to provide 4-log virus treatment under the Ground Water Rule, and to reduce sulfuric acid usage. Globaltech provided consulting engineering and permitting assistance to meet these goals.

Historically, the West WTP, a nanofiltration (NF) treatment facility, used chloramines for primary and secondary (residual) disinfection. In order to provide 4-log virus treatment, Globaltech proposed changing this practice to using free chlorine for primary disinfection and chloramines for residual disinfection in the distribution system. Our design included relocating chemical injection points and installing new residual analyzers for both free chlorine and total chlorine.

As part of the NF process, sulfuric acid had historically been added to lower the membrane feed pH sufficiently to prevent scaling of the nanofiltration treatment trains. Based on studies by others, the City decided to use a scale inhibitor, thus reducing the need for sulfuric acid to prevent scaling. However, the scale inhibitor increased the membrane feed pH from 5.9 to 7.0, resulting in the need to add sulfuric acid (albeit a much smaller dose) to the membrane permeate to lower the degasifier inlet pH below 6.0 for successful hydrogen sulfide removal.

To accommodate the necessary changes, Globaltech assisted in permitting the installation of new membrane permeate (MP)/membrane feed (MF) bypass blend sulfuric acid pumps in the existing acid feed room, and the relocation of injection points for sodium hypochlorite, ammonia, sodium hydroxide, and corrosion inhibitor.

Project Achievements / Benefits

• The new chemical configuration was approved by the Palm Beach County Health Department and approved for meeting 4-log virus treatment for the Ground Water Rule.
• Reduction in the amount of sulfuric acid used at the WTP resulted in cost savings and a safer working environment for staff.