Valuation of Environmental Management Alternatives of Distilleries

Abstract

This study compared the economic and environmental impacts of incorporating the Reverse Osmosis Technology in management of distillery slops with three other waste management system alternatives being considered by the distilleries. The alternatives showed different slops management schemes to include the discharge of anaerobically and aerobically treated slops to water bodies, use of anaerobically treated slops as sugarcane fertilizer and evaporation of slops. The alternatives were analysed based on the economic cost and benefits provided to the distillery, and its capability to meet the criteria set by distilleries in choosing among waste management alternatives among which: technical feasibility, environmental compliance, and economic feasibility. Benefits include recovery of resources as biogas and water from slops, and costs includes payment of discharge fees, transportation cost of slops to farms and operating expenses. Results of the financial analysis showed that Evaporation is the most feasible slops management alternative, however, since concentrated slops combustion technology, is not yet in place, discharge to water bodies remain the most viable alternative for distilleries, yet places distilleries at risk of non-compliance with the standard set for Color and TSS. The results however showed that if slops utilization is given commercial value, transferring the cost of hauling slops to the farmers, fertilization becomes the most viable alternative, and Reverse Osmosis scheme provides almost equal benefits with Evaporation. The study provided also information on the technical soundness of reverse osmosis in recovering clean water from slops, as provided from the data gathered from the pilot testing of the unit in one of the distilleries in Negros. Using the data gathered from the pilot study, it was showed that the maximum recovery attainable is 50%, which means that with the use of RO, distillery can lower the volume of their wastewater by 50%. The pilot study also established the optimum operating parameters required and from there, the operating costs was estimated which include cost of power and chemicals used in operation. The study also presented the economic benefits to farmers of slops utilization as fertilizer as well as its environmental impacts. Data gathered from previous slops fertilization study conducted by different organizations showed that farmers can benefit an increase in sugarcane yield by about 30% through using slops as fertilizer. Moreover, farmers can save an average of PhP 17,600 / hectare equivalent to their fertilization cost due to provision of free fertilizer and irrigation water through use of slops. Furthermore, the studies also presented that farms can benefit still from the positive impact of slops fertilization in terms of residual fertility and increased water availability. The study proposed the commercial application of reverse osmosis reject, which provides commercial value to slops as fertilizer in an amount equivalent to a hauling cost of slops at PhP 0.25/L. The study showed that at the estimated dose of 120 – 125 cum/hectare, the farmers will have yet a higher benefit cost ratio than the use of inorganic fertilizer. While the proposed commercialization of slops is not yet being considered by distilleries, due to the apprehensions of farmers on the long-term effect of slops fertilization, Zero waste management through use of Evaporation is the most feasible technology for distilleries, which merits the necessity of perfecting the concentrated slops combustion technology. However, at present, given the advantage of technical soundness of Reverse Osmosis and slops fertilization, it can provide the distillery with a management system that can ensure environmental compliance and economic and environmental benefits. Improvement in the operating conditions of the Reverse Osmosis should however be studied to maximize recovery to lower the amount of reject produced and operate the system at a lower operating cost. The applicability of RO Reject as fertilizer was taken in this study as equal to untreated slops effect to sugarcane crops from previous studies cited, however, it is proposed that it shall be investigated still to affirm its benefits to the crop or identify any impacts it may have to the crop, soil and water. The choice of distilleries of the appropriate waste management scheme to be implemented, depends largely on environmental regulations, and since as shown in the study that discharge to water bodies remain the most convenient management system for distilleries, it is recommended to provide a comprehensive study also of the effect of slops to the biological and physicochemical characteristics of water bodies, the same as it was conducted with the application of slops as fertilizer. This scientific study may improve the regulatory measures of the government to consider the actual effect of the waste specific to industry type, as each waste type has different effects to different hydrologic system.