UNEP(DEPI)/MED WG.357/Inf.9 1 April 2011 ENGLISH MEDITERRANEAN ACTION PLAN Meeting of MED POL Focal Points Rhodes (Greece), 25-27 May 2011 DEVELOPMENT OF PERFORMANCE INDICATORS FOR THE OPERATION AND MAINTENANCE OF WASTEWATER TREATMENT PLANTS AND WASTEWATER REUSE In cooperation with WHO UNEP/MAP Athens, 2011 TABLE OF CONTENTS EXECUTIVE SUMMARY .................................................................................................... 1 1. CONTEXT AND OBJECTIVES................................................................................... 4 2. CHARACTERISATION AND SAMPLING OF WASTEWATER ................................. 6 2.1 Representative parameters of wastewater pollution.................................................... 6 2.2 Wastewater sampling.................................................................................................. 8 2.2.1 Grab samples .......................................................................................................... 9 2.2.2 Composite samples................................................................................................. 9 2.2.3 Representative samples.......................................................................................... 9 2.2.4 Control of sampling equipment and preservation .................................................... 9 3. PRIMARY SETTLING................................................................................................. 11 3.1 General considerations................................................................................................11 3.2 Indicators of process operation ................................................................................... 11 3.2.1 Process control monitoring ...................................................................................... 11 3.2.2 Sludge thickness..................................................................................................... 12 3.2.3 Hydraulic loading..................................................................................................... 12 3.2.4 Skimming of floatable solids .................................................................................... 12 3.2.5 Odour control........................................................................................................... 13 3.3 Operational problems and solutions............................................................................ 13 4. ACTIVATED SLUDGE SYSTEMS.............................................................................. 15 4.1 General considerations................................................................................................15 4.2 Indicators of process operation ................................................................................... 16 4.2.1 Process control monitoring ...................................................................................... 17 4.2.2 Dissolved oxygen control......................................................................................... 18 4.2.3 RAS control............................................................................................................. 18 4.2.4 WAS control............................................................................................................. 19 4.2.5 Control of biological activity ..................................................................................... 20 4.2.6 Operational monitoring of activated sludge in water reuse systems ....................... 20 4.3 Operational problems and solutions............................................................................ 21 5. MEMBRANE BIOREACTORS.................................................................................... 24 5.1 General considerations................................................................................................24 5.2 Indicators of process operation ................................................................................... 26 5.2.1 Process control monitoring ...................................................................................... 26 5.2.2 Dissolved oxygen control......................................................................................... 27 5.2.3 Other parameters to control biological activity......................................................... 27 5.2.4 Control of membrane filtration performance ............................................................ 29 5.3 Operational problems and solutions............................................................................ 31 6. HIGH RATE CLARIFICATION.................................................................................... 34 6.1 General considerations................................................................................................34 6.2 Indicators of process operation ................................................................................... 34 6.2.1 Water quality monitoring.......................................................................................... 35 6.2.2 Optimisation of chemical dosage by jar tests .......................................................... 35 6.2.3 Control of chemical sludge recycling ....................................................................... 36 6.3 Other operational control parameters.......................................................................... 36 6.3.1 Control of sedimentation.......................................................................................... 36 6.3.2 Control of mixing...................................................................................................... 36 6.3.3 Main control points for regular cheeking.................................................................. 36 6.4 Operational problems and solutions............................................................................ 36 7. TERTIARY DEPTH FILTRATION............................................................................... 38 7.1 General considerations................................................................................................38 7.2 Indicators of process operation ................................................................................... 38 7.3 Operational problems and solutions............................................................................ 39 8. ULTRAVIOLET IRRADIATION................................................................................... 40 8.1 General considerations................................................................................................40 8.2 UV performance control strategies.............................................................................. 41 8.2.1 Monitoring of UV disinfection performance.............................................................. 41 8.2.2 Control strategies of UV disinfection ....................................................................... 42 8.2.3 Power supply........................................................................................................... 42 8.2.4 On-line cleaning systems ........................................................................................ 43 8.3 Main indicators of process operation........................................................................... 43 8.3.1 UV intensity............................................................................................................. 43 8.3.2 Hydraulic characteristics of the UV reactor ............................................................. 44 8.3.3 Wastewater effluent quality ..................................................................................... 45 8.3.4 Lamp aging.............................................................................................................. 46 8.4 Main operational and maintenance tasks of UV systems............................................ 46 8.5 Operational problems and solutions............................................................................ 47 9. CHLORINATION......................................................................................................... 49 9.1 General considerations................................................................................................49 9.2 Indicators of process operation ................................................................................... 49 9.2.1 Chlorine residual...................................................................................................... 49 9.2.2 Indicator bacteria concentration in disinfected effluent............................................ 50 9.2.3 Influence of wastewater quality on chlorine dose .................................................... 50 9.2.4 Contact time............................................................................................................ 50 9.3 Safety of handling and operation of chlorine products ................................................ 51 9.4 Operational problems and solutions ........................................................................... 52 10. CONCLUSIONS AND SUMMARY TABLE OF OPERATIONAL INDICATORS, CONTROL PARAMETERS AND TROUBLESHOOTING .......................................... 53 REFERENCES.................................................................................................................... 56 GLOSSARY ........................................................................................................................57 UNEP(DEPI)/MED