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					  Rural wastewater treatment in the United
                 Kingdom




                      Dave Diston, Huw Taylor
                School of Environment and Technology,
                        University of Brighton
Lakepromo Hungarian seminar: 10-14th October, 2007   Email: d.diston@brighton.ac.uk
    Characteristics of UK aquatic pollution
• Point/diffuse source contribution of P to surface waters is
  estimated to be 50:50 – N is biased towards diffuse
• Point source contribution judged to be of greater importance to
  riverine eutrophication (SRP; PO4)
• Government action (no specific rural sewage treatment plan):
   – Adoption of numerous EU Directives (UWWTD, WFD
      etc);
   – Agri-environmental schemes.
      http://www.defra.gov.uk/erdp/schemes/es/default.htm




     Lakepromo Hungarian seminar: 10-14th October, 2007     Email: d.diston@brighton.ac.uk
                 UK water industry – Key facts
- Transition from public to private (1989)
- Drivers:                                        Table 1: Price changes in the post-privatisation period (Ofwat)
     –         Removal from government
               financial regulations. Newly              Component % 1989-2006 Increase
               created private companies were
               granted increased borrowing                         (excluding inflation)
               powers free from Treasury
               constraints;
     –         New companies were floated on             Water             45.9
               the stock market, upon which
               previous accrued debts were               Sewage            36.7
               written off, making shares more           Combined          41
               attractive;
     –         The companies were allowed to
               increase water and waste
               processing prices (subject to
               regulation).
                                             Profit production was now of major importnace


         Lakepromo Hungarian seminar: 10-14th October, 2007            Email: d.diston@brighton.ac.uk
 Companies involved in water service industry
Water and sewage                                                                 Water only
                          98% of UK households are
                          connected to the mains sewerage network,
                          owned and operated by 11 private regional
                          water and sewerage companies




                                            London



                                 Brighton

      Lakepromo Hungarian seminar: 10-14th October, 2007              Email: d.diston@brighton.ac.uk
     Have goals of privatisation been achieved?


Table 2: Average annual capital investment

                                  1980-1985   1985-1990    1990-1995   1995-2000   2000-2005    2005-2010
 Water and Sewage companies       1.5bn       1.9bn        3.3bn       3.5bn       3.1bn        3.2bn

 Water Only                       n/a         n/a          0.2bn       0.3bn       0.2bn        0.2bn

 Total                            1.5bn       1.9bn        3.5bn       3.8bn       3.3bn        3.4bn


                                                    Privatisation



          Lakepromo Hungarian seminar: 10-14th October, 2007           Email: d.diston@brighton.ac.uk
        Current practices and methods available for the treatment of
         non-mains connected rural households (2%)in the UK (i)
       • Cesspool (storage only, little treatment)                                                   Filter
                                                                Gravel

    Pipe delivering
    sewage
    from single
    property (>15m)                                                                                           After construction,
                                                                                                              an airtight lid must
                                                                                                              be placed over
                                                                                                              cesspool
Capacity = 18 – 50 m3




      Pebbles and rocks

                    PROS = Cheaply & quickly built; CONS = No treatment, frequent emptying (££), access required

                 Lakepromo Hungarian seminar: 10-14th October, 2007             Email: d.diston@brighton.ac.uk
Current practices and methods available for the treatment of
   non-mains connected rural households in the UK (ii)
• Septic tank (primary sedimentation and some biological treatment)




                                                                                                              Up to 70% BOD
                                                                                                              removal




                                                           Design details can be found in British Standard BS 6297:1983

PROS = Decent treatment (30/20), de-sludging ~ 1 year, easily maintained ; CONS = Potential for bio-damage, backing up common


          Lakepromo Hungarian seminar: 10-14th October, 2007                        Email: d.diston@brighton.ac.uk
                                                                             Design and
                                                                             capacities vary
                                                                             greatly depending on
                                                                             population to be
                                                                             served




Two septic tanks in series for populations up to 30 persons (BS 6297:1983)


  Lakepromo Hungarian seminar: 10-14th October, 2007   Email: d.diston@brighton.ac.uk
Current practices and methods available for the treatment of
   non-mains connected rural households in the UK (iii)
• Packaged plants (sedimentation and biological treatment)




                                                                                 Various configurations
                                                                                 e.g. Activated sludge/
    PROS = High level of treatment; CONS = Expensive (6 person = £2,000+)        biofiltration etc.

       Lakepromo Hungarian seminar: 10-14th October, 2007           Email: d.diston@brighton.ac.uk
Current practices and methods available for the treatment of
   non-mains connected rural households in the UK (iv)
• Other options:
   – Small STW (same in
     principle to large STW –
     albeit on a smaller scale).
   – Tertiary treatment:
       •   Grass plots;
       •   Upward flow clarifiers;
       •   Effluent lagoons;
       •   Reed bed systems
        Technical drawings of all systems are available upon request

    Lakepromo Hungarian seminar: 10-14th October, 2007   Email: d.diston@brighton.ac.uk
                                   Extent of methods (i)

                        Table 3: Drainage attributes in UK households by construction date
Inc via private sewer
                        Type                   Pre 1945         1945-1990           1991-2001
                        Mains
                        connection                    95.9%               98.9%              97.8%
                        Septic                         3.0%                0.8%               1.7%
                        Cesspool                       0.7%                0.1%               0.0%
                        Private STW                    0.3%                0.1%               0.3%
                        Unknown                        0.1%                0.1%               0.2%

                                         Proportions have remained relatively stable




             Lakepromo Hungarian seminar: 10-14th October, 2007                 Email: d.diston@brighton.ac.uk
              Extent of methods by region (ii)
Table 4: Sewerage in England and Wales

        Region             % Sewered        Unsewered properties            Approxi mate         EA estimate(2) 000s
                                                  (000s)                   consents (1) 000s
 Anglian                             93                       167                           10                    -
 Northumbrian                        98                        21                            -                    5
 North West                          98                        55                            1                    -
 Severn Trent                        97                       100                            7                   70
 Southern                            95                        90                            -                   30
 South West                          88                        70                            -                   20
 Thames                              98                        94                            4                    -
 Welsh                               93                        93                            -                    -
 Wessex                              93                        72                            -                   50
 Yo rkshire                          97                        57                            -                   10
 ENGLA ND AND                        96                       819                           35                  185
 WALES
   1 Figures are estimates and apply to septic tanks only
   2 Figures are estimates and apply to septic tanks and package sewage treatment works


                                          No clear spatial patterns
     Lakepromo Hungarian seminar: 10-14th October, 2007                          Email: d.diston@brighton.ac.uk
 Current practices and methods available for the treatment of
       mains connected rural wastewater in the UK (i)
• Different experience of rural
  sewage processes to other
  Lakepromo partners – most
  rural households are
  connected to the mains
  sewerage network 
  sewage is processed in
  central STW
• Many rural properties are
  connected via Private
  Sewer Networks

     Lakepromo Hungarian seminar: 10-14th October, 2007   Email: d.diston@brighton.ac.uk
Current practices and methods available for the treatment of
     mains connected rural wastewater in the UK (ii)
•   Private Sewers
     – There are approximately 9,450,000
       properties served by private sewers in        Table 5: Condition of private sewers
       the UK of which it is estimated
       7,097,500 (75%) are located in rural                                                    ICG
       areas                                           % by length             1       2         3           4           5
     – Recent data indicated there were a                                      55      12        16          15          2
       total of 282,000 internal and external-
       flooding incidents per annum
       associated with all private sewers.           Note: Internal Condition Grade (ICG) 1: Acceptable condition
       However, Local Authorities only               ICG2: Short-term risk of collapse is minimal
       recorded 120,000 sewer related                ICG3: Collapse unlikely in near future, but likely to deteriorate
       flooding incidents, whilst Ofwat only         ICG4: Collapse likely in foreseeable future
       recorded 5,700 internal flooding              ICG5: Collapse imminent/collapsed
       incidents. Therefore, it is likely many
       sewer faults are not reported, limiting
       the chance of exercising damage
       mitigation strategies.



       Lakepromo Hungarian seminar: 10-14th October, 2007              Email: d.diston@brighton.ac.uk
Current practices and methods available for the treatment of
     mains connected rural wastewater in the UK (iii)

     Table 6: Reasons for private sewer faults
                                                               Number of inci dents per
      Problem Type                                             annum
      Ownership disputes                                                         45,000
      Flooding due to public sewer surcharging                                   42,000
      Flooding due to structurally defective private sewers                      46,000
      Flooding due to hydraulically defective private sewers                     20,000
      Failure of pitch fibre pipes                                               50,000
      Lateral drains                                                             58,000

                                                               Total faults = 261,000




    Lakepromo Hungarian seminar: 10-14th October, 2007              Email: d.diston@brighton.ac.uk
Other areas included in the UK Rural Sewage
      Treatment Information Package
•   History of UK sewage treatment
•   Administrative structure and legislation
•   Planning and implementation procedures
•   Methodology for selection of appropriate system
•   National special expertise (reed bed systems)
•   Investigation into nutrient stripping within the UK



      Lakepromo Hungarian seminar: 10-14th October, 2007   Email: d.diston@brighton.ac.uk
Thank you for your attention!

                   Questions after part II




Lakepromo Hungarian seminar: 10-14th October, 2007   Email: d.diston@brighton.ac.uk

				
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