Cacao pod shells (Theobroma cacao L) form biomass waste that can be used as raw material for liquid smoke because this biomass contains lignin, cellulose, and hemicellulose. This research studied the antimicrobial activity of liquid smoke from cacao pod shells on several common food-borne pathogens, such as Salmonella choleraesuis, Escherichia coli, Staphylococcus aureus, and Bacillus subtilis. The liquid smoke used was obtained from cacao pod shells that were pyrolyzed at 300 °C (T1), 340 °C (T2), and 380 °C (T3). Liquid smoke concentration varied from 1% to 5%. The antbacterial activity test was conducted using the Kirby–Bauer method. The results showed that liquid smoke produced from T1 and T2 (and at liquid smoke concentrations of 4% and 5%) could inhibit the growth of all the tested bacteria. At T3 and 1–5% of liquid smoke, only E. coli was consistently inhibited (inhibition zone = 6–7.05 mm), while the growth of S. choleraesuis and S. aureus was inhibited at 3–5% liquid smoke with the inhibition zone ranging from 6 mm to 7.2 mm. B. subtilis was inhibited by a 2–5% liquid smoke concentration. All the tested bacteria showed sensitivity to liquid smoke, but E. coli was the stronger resistant compared to others. The results of this study show that liquid smoke from cacao pod shells could be used as a preservative agent to inhibit microorganisms in food.

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In developing countries, the presence of wastewater is undesirable due to a costly investment for the treatment unit and energy-intensive for the operation. The wastewater treatment units in developing countries usually are not appropriately operated due to lacking operational cost. Therefore, it is not surprising if wastewater has never been considered a potential resource, even though it is rich in organics and nutrient substances. Biological treatment enables the conversion of wastewater into valuable products and energy. Sediment Microbial fuel cells (SMFCs) are emerging technologies envisaged as a feasible solution for simultaneous removal of carbonaceous compounds and generation of electricity. In SMFCs, power can be generated naturally by embedding an anode in the sediment and immersing the cathode in the water above the sediment. One of the most significant obstacles to upscaling and practical applications of the SMFCs appears to be the low-power output. The entire performance of an SMFC is determined by microorganisms, proper electrode materials, optimal SMFC designs, and process parameter optimization. This paper will discuss the recent progress of SMFC research related to its application in wastewater treatments and energy production. The advantages and obstacles of using SMFC in wastewater treatment are also presented.