Variability in the concentration of indicator bacteria in landfill leachate--a comparative study

Leachate collected from the collection ponds of four landfill sites was investigated and compared for total coliforms and E. coli concentration as representatives of fecal pollution. Concentration of total coliforms and E. coli was comparable for leachate obtained from Kulim Landfill Site (KLS) and Ampang Landfill Site (ALS) with little variations. However, the level of indicator bacteria was significantly lower for Kuala Sepetang Landfill Site (KSLS), whereas Pulau Burung Landfill Site (PBLS) had the lowest concentration for both total coliforms and E. coli. Considering the landfills are currently operational, with the exception of ALS, the presence of indicator bacteria implies their inactivation prior to discharge. High concentration of indicator bacteria in ALS is attributed to the run-off entering the leachate pond. Greater concentration of ammonia and salinity level were partly responsible for lower concentration of indicator bacteria in leachate from KSLS and PBLS, indicating that salinty and ammonia could significantly affect the survival of indicator bacteria.