ata acc to orderrelated documentation Without oi B2-KV-16-D Bevel-helical speed reducers B2

Flender/Flender Gear Units/Bevel-helical speed reducers B2

Nitrogen & operation & maintenance Ortho Ortho phosphate person; also depicted as capita () or head (hd) pe population equivalent &IDS piping and instrumentation diagrams PFD process flow diagram PLC programmable logical controller PST primary settling tank xii PWWF peak wet weather flow RAS return activated sludge ROI return on investment SAC specific absorbance coefficient SCADA supervisory control and data acquisition SRT sludge retention time SST secondary settling tank SSVI 3.5 stirred specific volume index at 3.5g MLSS/ TCOD total chemical oxygen demand; also re presented as COD unless specified otherwise TKN total Kjeldahl nitrogen TN total nitrogen Total total phosphorus ToU time of use TSS total suspended solids UCT University of Cape Town UPO unbiodegradable particulate organics USO unbiodegradable soluble organics VFA volatile fatty acids VFD variable frequency drive VSS volatile suspended solids WAS waste activated sludge, also surplus activated sludge (SAS) WRC Water Research Commission (South Africa) WSDP water services development plans WWTP wastewater treatment plant 1-1 1. Background 1.1 ENERGY EFFICIENCY IN WASTEWATER TREATMENT GLOBAL PERSPECTIVE Historically the design and operation of wastewater treatment plants focused on achieving the primary objective of protecting the environment and public he alth as required by regulations with no special attention paid to energy efficiency . Low energy costs meant that this could be achieved at reasonable municipal budgets as well as fair and affordable rates to the public. However in recent years global energy prices have continued to increase placing greater financial burden on municipalities whose budgets are already under pressure to finance not only other aspects of wastewater treatment, but meet other civic responsib ilities. In South Africa where historically electricity used to be much cheaper than other countries, the national electricity