Sustainable Development > Sewage and Sludge Treatment
SWHEPP will adopt advanced sewage and sludge treatment technologies to improve the treatment level. These technologies also reduce energy consumption and/or enhance renewable energy production for sustainable development.
  • SWHEPP Improvement Scheme will upgrade sewage treatment from secondary to tertiary level to meet the more stringent effluent discharge requirement. The following table presents the current and proposed effluent discharge standard before and after expansion.
    ParameterExisting Standards
    (Secondary Treatment) (mg/L)
    Proposed Standards
    (Tertiary Treatment) (mg/L)
    5-day Biochemical Oxygen Demand (BOD5)20(1)10(1)
    Total Suspended Solids (TSS)30(1)10(1)
    Total Nitrogen (TN)Not specified8(1)
    Ammonia Nitrogen (NH3-N)2(1)1.9(1)
    Nitrate and Nitrite Nitrogen (NO2-N & NO3-N)12(1)Not specified
    Total Phosphate (TP)Not specified1(1)
    E. Coli 100(2)/100 mL100(2)/100 mL
       1. The 95th percentile
       2. Monthly geometric mean
  • After SWHEPP Improvement Scheme, part of the tertiary effluent will be further polished (by other department) to reclaimed water for non-potable use, including toilet flushing and landscape irrigation. The daily reclaimed water production is estimated to be about 56,500 m3/day. It can help conserve our valuable potable water sources.
  • Adopt advanced and compact sewage treatment technologies (e.g. Membrane Bioreactor), which requires smaller footprint and also enhances effluent discharge quality and treatment capacity.
  • Adopt advanced sludge treatment technologies to enhance renewable energy (i.e. biogas production) recovery thereby reducing carbon emissions.
  • Adopt new and more effective and energy efficient sludge dewatering technologies for achieving 30% solid content for sludge disposal.