Biological nitrogen removal is generally accomplished by aerobic nitrification coupled with anoxic denitrification. Many commercial wastewater treatment plants (WWTPs) use external carbon source, such as methanol, to support heterotrophic denitrification process. Using organic wastes as an alternative to commercial carbon sources could thus be beneficial by saving the expense as well as reducing the environmental footprint. Here we report a full-scale (treating 2300 m3 wastewater/d) WWTP that previously utilized a butanediol-based organic waste as the sole external carbon source, which diversified the carbon sources by using a second organic waste generated from food waste recycling. Process parameters were extensively monitored for seven months at all biological unit processes, the aerobic and anoxic tanks, as well as the recirculation flow. Bacterial community structures were analyzed at anoxic tank using next-generation sequencing. The WWTP showed a stable nitrogen-removing performance over the seven months period. The estimated COD/N utilization ratio for food waste-recycling wastewater (FRW) was near 30. The bacterial populations significantly shifted during the operation. Lactobacillaceae and Prevotellaceae were the major bacterial families in the FRW, whereas the denitrification tank was populated by many families including Saprospiraceae, Nannocystaceae, Chitinophagaceae, Eubacteriaceae, and Rhodocyclaceae. Detailed discussion of the results will be presented at the conference.

This paper is a research on the economical analysis of the food waste recycling in order to enhance the proper management of food waste. In Korea, food waste is separated from the source compulsorily and treated on the feed, compost and other recycling plant. In this study the present economical evaluations of food waste recycling plants, such as collection & transportation, construction, operation cost and B/C analysis, is investigated. Based on a food waste recycling plants with a 50 ton/day, costing analysis was conducted by the present value criterion technique. The actual operation costs for directly operated plants were 88,358 won/ton for feed production, 79,015 won/ton for composting, 49,934 won/ton for other recycling, and 96,285 won/ton for incineration. When the profit from products sale for each recycling system and the depreciation cost of plants were considered, the costs for direct operation were 95,784 won/ton for feed production system, 96,824 won/ton for composting system, 56,576 won/ton for other recovery system and 143,776 won/ton for incineration system. And when a new facility is constructed, feed production could be favorable in operation cost and environmental aspects.

In this study, life cycle assesment (LCA) was conducted based on a functional unit of 1 ton of food waste recycling from collection and transportation to treatment processes such as feed production, composting, other recycling and incineration for 45 public food waste recycling plants. The Korean life cycle inventory (LCI) data were used for the main input material and energy. For the other input data, which could not be provided by the Korean LCI database, data of other countries were used from the database by Ecoinvent, and the strength of food wastewater for LCI DB was divided low and high concentration. In case of low strength of food wastewater, environmental impacts were suggested incineration, composting and feed production in the order, where collection and transportation were identified as the major influencing factors by contribution analysis and sensitive analysis. Contrary, in case of high strength of food wastewater, environmental impacts were suggested composting, feed production and incineration in the order, where treatment of food wastewater was identified as the major influencing factor. Therefore, discharge volume as well as concentration of food wastewater was found to be important parameter of the LCA.