Use Ferric Chloride enables plant to reduce phosphorus discharge levels and save on costs with improved solids production.
CHALLENGE: INCREASED PHOSPHORUS LEVELS IN HOT WEATHER CONDITIONS.
The North Las Vegas Water Reclamation Facility (WRF), built in 2011, utilizes submerged membrane bioreactor technology to produce reclaimable water. The WRF runs an average flow of 17 million gallons a day (MGD) with a 25 MGD maximum capacity.
Discharge permit requirements allow only 16 kg phosphorus per day, or approximately 0.23 parts per million (PPM), during March through October. The plant needed a solution for reducing phosphorous levels during these months.
SOLUTION: ADDING FERRIC CHLORIDE AT WATER TEMPERATURES ABOVE 28°C.
Studies conducted at the North Las Vegas facility showed an increase in phosphorus organisms when water temperatures reached 28°C.Ferric Chloride removes phosphorus compounds by adding 750-1500 litres/day from March through October.
RESULTS: LOWER PHOSPHEROUS LEVELS AND IMPROVED BIO SOLIDS PRODUCTION
This process sequence has been very successful. By adding ferric chloride, phosphorus discharge levels were reduced to 20-25% below the mandated limit. Additionally, the plant produced better sludge with 22–23% versus 30% in bio solid production, resulting in $100,000-$150,000 annual savings.
Through CH2MHill, the technical consultant on the project, Kemira has since leveraged its success here to also supply coagulants for similar membrane plants in Henderson, Nevada and in the US Pacific Northwest region.