Catalino G. Alfafara

A fungus capable of producing ethanol from various carbon substrates was screened for direct ethanol production from lignocellulose. Fusarium moniliforme BIOTECH 3170 produced ethanol from glucose, xylose, and cellobiose after three days with theoretical yields of 86.4%, 68.6%, and 45.4%, respectively. The coculture of glucose and xylose progressed sequentially at 79.2% of the theoretical yield, with both sugars completely consumed in five days. The solid-state consolidated bioprocessing of cellulose produced 25.2 g/L of ethanol after 20 days. After 28 days of the integrated biodelignification and consolidated bioprocessing of Napier grass at solid-state conditions, up to 10.5 g/L of ethanol was produced, corresponding to an ethanol yield of 0.032 g/g biomass. Given a sufficient carbon source, the screened fungus could produce up to 42.06 g/L ethanol. F. moniliforme BIOTECH 3170 demonstrated the characteristics of a fungus for potential ethanol production from cellulose, mixed sugars, and lignocellulosic materials.

Rice is a staple food crop, and its production generates large volumes of agricultural waste, rice straw. Several studies have proven that open-field burning and soil incorporation are unsustainable practices of managing rice straw, but remain as prevalent methods of treating and disposing of rice straw. An alternative solution is to harness the energy from rice straw via a small-scale heat conversion system for paddy drying applications, which can reduce rice grain post-processing costs and improve paddy storage conditions. This study investigated the energy flow, Greenhouse Gas (GHG) emissions, and cost of a small-scale rice-straw-based heat generation (RBHG) system using a downdraft furnace and a dryer simulator setup. The highest input energy and GHG emissions of 92% and 68%, respectively, were from the heat generation stage. The RBHG energy ratio was between 1.4 and 1.7, and the percent net energy was between 39 and 67%. The best case of RBHG offers a possibility of a net GHG avoided (−61 kg CO₂-eq Mg⁻¹), while the worst case (856 kg CO₂-eq Mg⁻¹) has a net GHG emission comparable with soil incorporation. The average total cost of RBHG is 0.096 USD kWh⁻¹. Overall, RBHG technology has the potential to improve energy flow, GHG emissions, and the cost of rice production systems.

Background. The Marilao, Meycauayan and Obando river system (MMORS), in the Philippines is home to many precious metals refineries, where local artisanal gold smelting industries use silver to draw gold out of used jewelry. Copper recovers the silver. The copper-rich wastewater contributes to local pollution. Alternative methods for silver recovery include electrolytic recovery: removal of silver ions from solution, and conversion of the ions into metallic silver. Objectives. Explore operation and scale-up for the electrolytic recovery of silver for small-to-medium-scale used gold smelting plants. Methods. Effects of current and time were investigated in a laboratory scale, magnetically-stirred electrolysis reactor, using a sintered platinum anode and a stainless steel cathode. Silver recovery (the removal of silver ions from solution) was evaluated at different levels of constant operating current, and data was used to determine charge dose as the scale up and operating factor. Charge dose was then used to obtain the operating conditions on a pilot scale (100 L) system. A preliminary pilot test assessed silver recovery performance. Results. Higher silver removal rates were noted at higher operating currents. Electrodeposition at 9 amperes showed 98.7% silver recovery after 30 mins. The charge dose for silver electrodeposition was 1.23 coulombs/mg silver ions removed, while the average electrolysis energy requirement was about 0.59 kilowatt hours/kg of silver removed. Conclusions. Preliminary comparisons on a 100-liter scale, showed the electrolytic process had a higher silver removal (~ 90%) compared to copper displacement (~ 65%). Results are useful for the process design of a complete field test system.