Cultus Lake Park Sanitary Sewer Infrastructure Assessment

Fraser Valley Regional DistrictCultus Lake Sanitary Sewer Infrastructure Assessment – Final Report4.5.4 UV SizingTable 12 provides a preliminary sizing for the UV reactorsTable 12: Preliminary sizing of UV reactorsDescription Units Option 3Maximum peak flow L/s 33Total number of reactors 3Number of duty reactors2 duty / 1 standbyCapacity of each reactor L/s 16.54.6 Sludge TreatmentFor all treatment of processes, sludge will be produced and portion of the sludge (wasteactivated sludge) has to be further processed to reduce its volume before transporting itto disposal sites. Achieving a more concentrated sludge, prior to disposal, lowers thehauling and transportation costs from the treatment plant to the disposal site, and lowersthe number of sludge trucks that has to go through the community. Increasing the sludgeconcentration from 1% to 15% reduces the hauling and transportation cost to 1/15 of thecost. .The sludge concentration from the biological process is in the range of 0.5% – 1.0 %.Normally, mechanical dewatering units such as belt press or centrifuge require the feedsludge to be concentrated to 2% to 4%. A sludge thickening process is needed to thickenthe sludge to these concentrations (2 %?4 %). Using either belt press or centrifuge canachieve a minimum sludge concentration of 15%.Table 13 provides description, advantages and disadvantages of each processTable 13: Belt Press and Centrifuge – Advantages and DisadvantagesProcess Description Advantages DisadvantagesBelt FilterPressBiosolids pressedbetween two porousmoving belts.• Relatively low capitalcost,• Relatively low powerconsumption,• High solids capture withminimum polymer• Continuous feed,• Moderate cake solidsconcentration,• Moderate throughoutcapabilities versusspace requirement• Open design providesgood visual controlcapability for processperformance• Can be provided with anintegrated sludgethickening unit• Housekeeping –open design does notallow containmentduring processupsets• Moderate operatorattentionrequirements;• Odour potential,• Sensitive to incomingfeed characteristicsProject No. 30825 – September, 2012 Page 21