Article provided by State Water Resources Control Board
The Graton Community Service District Wastewater Treatment Plant has been innovatively renovated and the plant designed, by Lescure Engineers, won the January 2015 American Council of Engineering Companies (ACEC) special merit award.
The overall concept was to modify the wastewater treatment plant so that it has zero discharge. In order to move towards this goal it has several eco-friendly designs that were combined with three major innovations.
One major innovation is a new disinfection system that pasteurizes the waste (heated for 10 seconds at 162 degrees) and therefore doesn’t use chlorine in the final treatment stage. This is both environmentally friendly and makes it safer for the operators. The operators do not have to worry about the possibility of excess chloroform exposure
Another of the major innovations is the suspended air floatation (SAF) that is used to remove algae. This is the first time this technology has been used in a municipal WWTP. The solids are removed and pumped to the composting area.
The third major innovation is the compressible media filter, or Fuzzy filter. It can adjust the percentage of compression and adjust the turbidity. Plate compresses the Fuzzy Filters (pink balls) at the lower end of the compression.
Robert Rawson, the former Chief Plant Operator realized that the holding ponds had an excessive amount of duckweed on the surface of the ponds. He knows firsthand the problem it creates when the diaphragm pump pulls the weeds in and it’s sucked into the pipe. He engineered an environmentally friendly solution by inventing a floatation box to skim the water and collect the duckweed, which in turn is added to the biosolids compost pile. The duckweed helps absorb nitrogen and phosphates in the composting process.