Thesis - faculty.ait.ac.th - Asian Institute of Technology

Chapter 4
Results and Discussion
4.1 Simulation of Leachate Characteristic for Treatment of Middle Aged Leachate
Leachate varies widely in quantity and in composition from one place to another
(Kennedy, et al., 1988). Such variability along with other factors make the applicability of
a method to treat leachate highly dependent on the characteristics of the leachate and
tolerance of the method against changes in leachate quality (Henry, et al., 1982). As
mentioned in section 2.13.1, it is difficult to predict the applicability of the leachate
treatment sequence with varying leachate quality. To overcome this problem, leachate with
a quality emulating the medium landfill leachate was simulated, and used in this
experimental work.
To arrive at the appropriate leachate quality to be taken for the study, a survey on the
medium aged leachate in Asian context is required. Table 2.3 gives the typical
characteristics of the middle aged landfill leachate. The medium-aged leachate contains
COD ranging of 5,000 to 10,000 mg/L and BOD/COD ratio of 0.1 to 0.5 (Qasim and
Chiang, 1994; Amokrane, et al., 1997). The medium landfill leachate is usually less
biodegradable than the young leachate. The high ammonium concentration of around 2,000
mg/L makes the medium aged leachate treatment even more complicated. The NH4 + -N is
dominant among the nitrogen forms making it an important parameter to be considered in
leachate treatment. Another important parameter taken into consideration is the alkalinity.
The alkalinity is also found to be high in leachate and significant in leachate treatment. As
the leachate is nutrient deficient in terms of phosphorus, and often phosphorous
supplement was added to enhance the leachate treatment. Based on the literature review, a
simulated leachate quality was used with BOD/COD ratio ranging from 0.35 to 0.45, COD
ranging from 7,000 to 9,000 mg/L, and total nitrogen ranging from 1,800 to 2,000 mg/L as
described in Table 3.1.
The leachate simulated for the study was prepared by combining the leachate
collected from Pathumthani Landfill Site (PS) and Ram-Indra Transfer Station (RIS).
Table B-1 of Appendix B gives the leachate quality of the two sites along with the mixed
leachate quality. The BOD/COD of the mixed leachate was found to be around 0.44-0.45.
Table 4.1 presents the consistency of the simulated leachate used in the study.
Table 4.1 Compositions of Leachate Simulated from Leachates Obtained from Pathumthani
Landfill Site (PS) and Ram-Indra Transfer Station (RIS)
COD BOD BOD/COD NH3-N TKN
(mg/L) (mg/L)
(mg/L) (mg/L)
7,715 3,484 0.45 1,791 2,072
7,733 3,460 0.45 1,623 1,850
7,404 3,353 0.45 1,624 1,969
7,248 3,205 0.44 1,558 1,898
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