Pseudomonas putida is a potential strain in biological treatment to remove mercury contained in the effluent of petrochemical industry due to its mercury reductase enzyme that able to reduce ionic mercury to elementary mercury. Freeze-dried P. putida allows easy, inexpensive shipping, handling and high stability of the product. This study was aimed to freeze dry P. putida cells with addition of lyoprotectant. Lyoprotectant was added into the cells suspension prior to freezing. Dried P. putida obtained was then mixed with synthetic mercury. Viability of recovery P. putida after freeze dry was significantly influenced by the type of lyoprotectant. Among the lyoprotectants, tween 80/ sucrose was found to be the best lyoprotectant. Sucrose able to recover more than 78% (6.2E+09 CFU/ml) of the original cells (7.90E+09CFU/ml) after freeze dry and able to retain 5.40E+05 viable cells after 4 weeks storage in 4oC without vacuum. Polyethylene glycol (PEG) pre-treated freeze dry cells and broth pre-treated freeze dry cells after freeze-dry recovered more than 64% (5.0 E+09CFU/ml) and >0.1% (5.60E+07CFU/ml). Freeze-dried P. putida cells in PEG and broth cannot survive after 4 weeks storage. Freeze dry also does not really change the pattern of growth P. putida but extension of lag time was found 1 hour after 3 weeks of storage. Additional time was required for freeze-dried P. putida cells to recover before introduce freeze-dried cells to more complicated condition such as mercury solution. The maximum mercury reduction of PEG pre-treated freeze-dried cells after freeze dry and after storage 3 weeks was 56.78% and 17.91%. The maximum of mercury reduction of tween 80/sucrose pre-treated freeze-dried cells after freeze dry and after storage 3 weeks were 26.35% and 25.03%. Freeze dried P. putida was found to have lower mercury reduction compare to the fresh P. putida that has been growth in agar. Result from this study may be beneficial and useful as initial reference before commercialize freeze-dried P. putida.

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Wastewater from oleochemical industry contains high concentration glycierin, chemical oxygen demand (COD) and total suspended solids (TSS) that can cause environmental pollution if discharged without proper treatment method. Currently, oleochemical industry used reverse osmosis membrane and submerged bed biofilm reactor to treat their wastewater. In this work, other method namely electrocoagulation treatment that capable to achieve a high removal of color, COD, biological oxygen demand (BOD) is employed. The objective of the study is to determine the optimum operating condition such as initial pH (6-9), applied current (4.0-8.0A), type of electrode (aluminium & stainless steel & and retention time (10 – 40 min) on degradation of COD and TSS in wastewater from an oleochemical industry using this process. The experimental results showed that the pollutant removal efficiencies of COD and TSS can be achieved at 62.64% and 66.12% respectively, of the initial concentration of parameters using aluminium electrode at the optimum conditions of pH 7.5, applied current 6 A and reaction time of 30 min. All the findings of the study revealed that treatment of oleochemical wastewater by electrocoagulation process at optimum conditions can be used as a treatment.