Presentation on theme: "Small Sewage Treatment Plants"— Presentation transcript:
1 Small Sewage Treatment Plants CE Marking and Regulations
2 IntroductionSmall sewage treatments plants are characterised as plants serving 50 Population Equivalents (PE) or lessThere has been a large number of changes in the regulation and standards that these systems are now expected to comply with.
3 History – British Standards Standards often quoted with regards to Small Plants are:BS6297:1983 Design of installation of small sewage treatment works and cesspools – REPLACED WITH BS6297:2007 Cope of practice for the design installation of drainage fields for use in wastewater treatmentBS7781:1994 Procedure for type testing of small biological domestic wastewater treatment plants – NOW WITHDRAWN
4 Current ‘UK’ Standard – BS EN 12566 EN “Small wastewater treatment systems up to 50PT” contains the following British Standards:BS EN :2000 Prefabricated septic tanksBS EN :2005 Packaged and/or site assembled domestic wastewater treatment plantsBS EN :2007 Septic tanks assembled in situ from prefabricated kits
5 Current ‘UK’ Standard – BS EN 12566 Code of Practice:TR Code of Practice for in-situ constructed soil infiltration systemsand Standards in preparation:EN Pre-treated Effluent Filtration systemsEN Prefabricated treatment units used for septic tank effluentEN Prefabricated tertiary treatment units
6 BS EN 12566-3:2005 – Confusion over Status The EN standard includes for a period of “co-existence” of national standards, however there are no existing/conflicting standards in the UK.Therefore, BS EN is the ONLY standard that all small treatment plants up to 50PE MUST comply to.
7 Key Points of BS EN 12566-3 BS EN 12566-3:2005 specifies: Requirements (e.g. design, structural loads)Test methodsEvaluation of conformity and marking of plantsInstallation, operation and maintenance instructions
8 Requirement of Small Plants Robust, watertight and corrosion resistantEquipped with alarm functionInlet/outlet pipe: 100mm ID ≤ 4m3/d150mm ID > 4m3/dSized in accordance with national regulations (EA and BW CoP, Flow and Loads)
9 Test Methods for Small Plants Watertightness Test (different test methods)Treatment Efficiency Test (38-week) incl:Normal, under and over loading periodsPower breakdownLow occupation stress (holiday simulation)Structural Test (different methods, incl. physical and calculations)
10 Compliance and Marking of Plants Compliance of plants is tested and certified by independent test facilities in Europe (none in the UK)Manufacturers shall affix CE-certificate stating:Name and construction material of plantWatertightness and structural test resultsremoval efficiencies for BOD, SS and AmmoniaEnergy consumption
11 UK Foreword of BS EN 12566-3 UK foreword was amended in May 2007 Plants shall demonstrate a minimum effluent quality of 20/30/20 (BOD/SS/Ammonia), e.g. achieve removal efficiencies ofBOD > 93% (based on 300mg/l influent conc.)SS > 88% (based on 250mg/l influent conc.)Ammonia > 50% (based on 40mg/l influent conc.)
12 Marsh Sewage Treatment Plants Have been tested and certified to BSENThey have passed with a BOD level below 15mg/litreTest certificates are available