Tiberiu Apostol

In the present and projected context of an increasing worldwide demand for food, the intensification of climate change effects on agriculture, and the depletion and degradation of natural resources, global actions must be taken to assure future food security for all people. Improper practices along the food supply chain, from primary production to consumption, generate huge quantities of food waste. Building a circular bioeconomy that feeds recycled materials back into the economy and minimizes the loss of resources will be an important step in introducing the world’s food system to a sustainable path. The present case study describes an enclosed on-site composting system for food waste, operated in real-life conditions. The composting equipment was installed for a restaurant with specific needs in November 2020, located near a shopping center in Bucharest, the capital city of Romania. The physical, chemical, and biological characteristics of the compost came from a mix of food waste from a retail restaurant and sawdust pellets used as absorbent material, and these were analyzed to monitor compost quality and establish valorization opportunities. Two different monitoring campaigns were developed and the biological parameters were analyzed. The second monitoring campaign indicated that the compost was contaminated with Escherichia coli and Salmonella spp. When handled correctly and according to instructions, the composting process eliminates pathogens that may be present in food waste, such as Escherichia coli, Salmonella spp., etc., resulting in a high-quality compost that can be valorized in agriculture such as fertilizer or soil improver. Our results demonstrated that even when maintaining the same composition of raw materials in the composter, the quality and properties of the compost are greatly influenced by its operating conditions. Quality management procedures must be enforced and procedures must be strictly followed for the compost to be considered compliant. Compost that does not meet the requirements according to the regulation in force is again subjected to composting. If, after repeating the operation, the compost is still noncompliant, it is declared nonrecyclable waste, and must follow the specific procedure for such waste.

Food waste generation is increasing at an exponential rate, affecting the environment, food security, and causing major economic issues worldwide. The main aim of the current research is to investigate a novel composting technology that is still in its early stages of development. The proposed composting technology combining thermophilic composting with the use of advanced automated processing reactors. Starting from a qualitative and quantitative analysis of the waste generated at retail-stores, the most significant difficulties associated to waste management as well as the main characteristics of the discarded waste were identified. The findings allowed to design and evaluate the real operating performance of an automated thermophilic composting prototype (working in a decentralized regime), with the goal of delivering a faster processing system, improving operational efficiency, reducing expenses, and lowering environmental impacts. The proposed operating technique showed a high capacity for pathogens and seeds removal, the waste input mass reduction of 88%, and efficiency in food processing (2235 kg of fruits and vegetables in a 14-days timeframe).

This paper presents experimental results regarding anaerobic co-digestion of the organic fraction of municipal solid waste and fruit and vegetable waste in order to establish the efficiency of a 2 m³ volume pilot plant in terms of biogas and methane yield and stability of the process. The research study presents the feasibility of developing anaerobic digestion as an effective method for municipal solid waste management. The experiments were conducted in mesophilic conditions (35 °C). Domestic waste water was used as inoculum. The results showed that the inoculum presence, temperature, and pH control, were essential in order to improve biogas production and its composition. Using liquid inoculum, the CH₄ percentage in the biogas oscillated between 44% and 51%, and the biogas production from 0.504 and 0.6 m³/day. Compared to domestic waste water, animal manure increased the CH₄ concentration in biogas (up to 63%), while the daily biogas production increased by 26% and varied from 0.693 to 0.786 m³. The cumulative biogas production at the end of the experiments were 11.7 m³ and 15.89 m³, respectively. Using inoculum and co-digestion, the plant startup time was significantly reduced, the total solids content decreased from 22.7% to 19.8%, while the volatile solids decreased from 37.6% to 31.2%.

In the new legislation framework enacted by new member countries of the European Union (EU), the characterization of municipal solid waste (MSW) represents an important instrument for local governments and sanitation operators in setting and achieving targets for waste recycling and recovery. This paper presents the results of a study conducted in accordance with the Romanian methodology for domestic wastes characterization ROMECOM, aiming to provide a proper basis for developing clear and realistic forecasts in current municipal waste management, based on MSW composition and generation rate. The analyzed MSW came both from areas where the waste is collected in mixed and separate ways, in urban and rural areas. The MSW composition by fraction is detailed for dense urban areas, urban areas, rural and touristic areas from Romania. Based on these results, the MSW composition was determined for the eight development regions in Romania, and a generation rate of 0.9·kgMSW inhabitant⁻¹·day⁻¹ for the urban region and 0.4·kgMSW inh⁻¹·day⁻¹ for the rural region was established. The calorific values of urban and rural areas were determined as 6801 kJ·kg⁻¹ and 5613 kJ·kg⁻¹, respectively. In the perspective of sustainable development in this technical area, based on the obtained results and on the prognosis made for the following years, two proposals for urban and rural areas were developed for MSW treating options improvement. The two systems are characterized by selective collection (different efficiencies for urban and rural areas) with subsequent recovery of the separated materials and energy recovery of the residual waste in a large-scale waste to energy (WTE) plant.