Journal of Bioremediation & Biodegradation

Abstrait

Using Chlorella vulgar is to Decrease the Environmental Effect of Garbage Dump Leachates

Sarunporn Thongpinyochai, Raymond J Ritchie

Waste treatment in Phuket, Thailand produces two sources of leachate. The Landfill Leachate (LF) has low BOD (60-405 mg O2/L) and heavy metal levels are below legal limits. Garbage awaiting incineration, Garbage Pit Leachate (GPL), also produces a second leachate with a very high BOD (50-100 g O2/L) and NH3-N (763-2,045 mg/L). Zn and Cr exceed standards but Cu and Pb are low. Chlorella vulgaris was tested for its ability to decrease NH3-N, NO3--N, Total-P, BOD and COD and to remove and/or immobilize heavy metal at varying dilutions of leachate. The objectives of this study on Chlorella bioremediation were: 1) measure Chlorella growth in Landfill and Garbage Pit Leachate, 2) measure the effectiveness of Chlorella to decrease the physico-chemical parameters NH3- N, NO3-N, Total-P, BOD, COD 3) measure heavy metal removal from leachates. The minimum inoculum of Chlorella biomass which can grow in the LF was Chlorophyll a 0.259 μg/mL (A750=0.075). Chlorella significantly lowered its BOD and COD: Cr and Ni, already low in landfill leachate, were decreased by 70% and 66%. Chlorella grew well in LF diluted 30 % with tapwater: % removal of NH3-N (53.91%), BOD (52.78%) and COD (51.05%). The GPL was very toxic: only 10-20% dilutions of GPL were tolerated by Chlorella and cultures required continuous aeration by shaking to grow. The minimum necessary inoculum of Chlorella biomass in the GPL was Chlorophyll a=0.92 μg/mL (A750=0.19). In 20% dilution of GPL, Cr and Zn were decreased by 33% and 90% respectively to legal levels. % removal of NH3-N (41.5%), NO3--N (32.4%), Total-P (55.1%), BOD (49.2%) and COD (50.8%). Chlorella inoculations with a biomass of 1.17 μg/mL Chlorophyll a (A750=0.202) removed 90% of the Zn.