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Report: Alex Renew Chapter Tour

Twelve chapter members and friends visited the AlexRenew Water treatment facility in Alexandria on Saturday, June 22. AlexRenew (established in 1952 by the Alexandria City Council as the Alexandria Virginia Sanitation Authority) situated on 34 acres along the north side of the Capital Beltway on the Virginia side of the Wilson Bridge. Its design capacity is 54 million gallons of wastewater per day but can handle up to 108 million gallons per day during peaks. AlexRenew serves 350,000 customers in Alexandria and portions of Fairfax County, processing 13.7 billion gallons of waste water per year and producing 23,000 wet tons of bio solid waste residue per year used as fertilizer by farmers in 11 Virginia counties, keeping 34.8 million lbs. of sediment from reaching the Chesapeake Bay watershed. It has reduced of energy use by 11% since 2008 to 4 million kw hours per year and reclaimed 1.7 billion gallons of water for re-use. It also removes 4.3 million lbs. of nitrogen and 0.7 million lbs. of phosphorous from dirty water while producing 143 million cu. ft. of methane per year of which 124 million cu. ft. is recycled to provide 32% of energy needs. It also saved $3.4 million per year by conserving fresh water. An interesting feature of the plant is an underground storage reservoir built with a community athletic field at ground level providing peak storm water storage capacity. There are also underground tunnels to service underground piping throughout the facility. We toured each of the nine major processing steps (above ground):

  • Initial screening
  • Secondary screening
  • Primary settling
  • Biological Nitrogen removal (covered sludge and “activated sludge”)
  • Secondary settling (produces secondary effluent)
  • Advanced Treatment

  • Tertiary plate settlers, gravity filtration through sand filters
  • UV disinfectant by UV lamps
  • Post aeration (dehydrate solids to reduce transportation cost of solid waste)
  • – Solids Processing
    – Methane used to create steam for pasteurization heat exchangers
    – Anaerobic digesters (30 to 40 day “digesting”)
    – Dewatering centrifuges

Submitted by Joe Scheibeler, Chapter Secretary

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