Monitoring of Fruit and Vegetable Waste Composting Process: Relationship between Microorganisms and Physico-Chemical Parameters

Abstract

The aim of this study was to investigate and evaluate the composting potential of fruit and vegetable waste with sawdust in different combinations and to establish the relationship between microorganisms and physico-chemical parameters. Three samples were made with the C/N ratios of 50 (sample 1), 45 (sample 2), and 30 (sample 3) by adding fruit waste (apple, banana, orange, and kiwi peels) and vegetable waste (cabbage leaves, potato and carrot peels). The total amount of fruit and vegetable waste was approximately 2 kg in each sample to which different quantities of sawdust were added (1.23, 0.14, and 0.203 kg) in order to obtain the C/N ratios proposed and to limit the odor. Composting process was monitored over 70 days, while physico-chemical and microbiological analyses were performed. Results showed that in the first week pH is acidic and electrical conductivity values are high for all three samples, and then the pH values increase during the composting process, while electrical conductivity values decrease. The nitrogen content is low in all samples and will decrease during the first five weeks of the composting process, then begin to increase slightly. Cr, Cu, Ni, and Zn values in the all three compost samples are below threshold values. During the composing process the microbial communities are constantly changing. The compost was successfully obtained and meets the requirement standards for agricultural use. It can be concluded that there is statistically significant association between the microorganisms and physico-chemical indicators.

Monitoring of Food Waste Anaerobic Digestion Performance: Conventional Co-Substrates vs. Unmarketable Biochar Additions

“…Simultaneously, a gradual drop in SBY, by approximately 50% from week 24 until the end of the running of the digesters, was recorded. Hence, VFA and TAC behaviors were also consistent with the trends in biogas production, where well-buffered digesters generated improved volumes of biogas [64,65]. In this sense, the operational conditions, particularly the feedstock mixture and the OLR variations (p-value < 0.0001), significantly influenced the efficiency of the existing microorganism community in terms of sustaining AD progress and converting polymers to methane.…”

“…This advancement was originally due to the balance of the C:N ratio ensured by both WS and CM. However, this might play a key role by providing the methanogens with some of the trace elements required to stimulate the activity of the enzymes and co-enzymes for better methane production, and particularly by buffering the digesters at certain organic loads [10,64]. With regard to these experimental conditions, R2 was characterized as having a stable pH and, consequently, constant VFA levels.…”

Decentralized Processing Performance of Fruit and Vegetable Waste Discarded from Retail, Using an Automated Thermophilic Composting Technology

“…The mechanism for obtaining high-quality compost from fruit and vegetable wastes was also investigated [41] to establish the relationships created between microorganisms and physicochemical parameters. The mathematical model highlighted the fact that strongest positive relations are created between moisture and carbon contents, moisture and coliform bacteria, moisture and C/N ratios.…”

Effects of co-substrates’ mixing ratios and loading rate variations on food and agricultural wastes’ anaerobic co-digestion performance

“…When it comes to OLR variation, VFA:TAC ratios were identified to evaluate the effects of the risen loading rates in order to optimize this latter for different feedstocks' [71]. Moreover, attaining an OLR of 3.6 VS/ m 3 .d, a significant increase of VFA:TAC ratio was identified for almost all the reactors to peak at 0.61, entailing the inhibition of the process and the decline in terms of biogas and methane yields.…”