From anaerobic to aerobic treatment: upcycling of digestate as a moisturizing agent for in-vessel composting process

Chaher, Nour El Houda; Hemidat, Safwat; Chakchouk, Mehrez; Nassour, Abdallah; Hamdi, Moktar; Nelles, Michael

doi:10.1186/s40643-020-00348-0

Cited by 10 publications

(6 citation statements)

References 45 publications

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“…With reference to Casini et al, (2019), the recorded C:N ratio trends might be attributed to the high rate of carbonaceous component consumption during the first five weeks, as well as the lower nitrification rate which was in accordance with the current findings [39]. In the same context, Chaher et al, (2020) reported that a balanced utilization of nitrogenous and carbonaceous elements serves as an efficient indicator to point out the maturity of the end-product which was in line with the identified C:N ratios (at day 37) of both A1 and A2 attaining 12.78 and 14.51, respectively [34].…”

Section: C:n Ratio Profile During the Composting Processsupporting

confidence: 90%

“…In fact, MC fluctuations were assigned as an indicator pointing out the need to add further amount of MA. Otherwise, an estimated volume of both fresh water and digestate was determined from the beginning of the process referring to the initial feedstock mixture moisture content and the required MC range [20], [34]. Table 1 displays the trial ingredients and the composting time.…”

Section: Methodsmentioning

confidence: 99%

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Digestate Post-treatment and Upcycling: Unconventional Moisturizing Agent for Food Waste In-Vessel Composting

Chaher

Nassour

Hamdi

et al. 2021

Waste Biomass Valor

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Nowadays, Tunisia faces challenging environmental and energy issues which relate mainly to the implementation of an appropriate solid waste management system capable of dealing with the high production of biowaste on the one hand, and the increased need for water and energy resources on the other. Therefore, the current study is intended to develop a closed cycle technical concept treating mainly food waste (FW) through combined biological processes. In this approach, FW anaerobic digestion (AD) was destined to provide a valuable input material for FW in vessel-composting by exploiting the produced digestates. To this end, the gathered AD-effluents of three systems (D1, D2, D3) were entirely analyzed to select, as a further step, the most suitable one to be subject of the suggested post-treatment. Hence, several physiochemical parameters were examined as key performance indicators. It mainly consisted of moisture content, pH, C:N ratio and heavy metals contents. The current findings depicted that the generated digestates were characterized by a high moisture content which inspired its utilization as an unconventional moisturizing agent (MA) aiming to reduce the fresh water consumption during the composting process. Thus, two experimental setups were carried out to evaluate the effect of the selected digestate on FW-in-vessel composting process performance, as a non-standard MA inserted to A2, comparing to the unamended one (A1) which was moistened by fresh water. In fact, basing on the above-mentioned criteria, the relatively high C:N ratio (of around 15), as well as the relatively significant rate of the required macro- and micro-nutrients promoted the exploitation of biochar-rich digestate (D3) as not only an efficient unconventional MA, but also as a composting process booster. Furthermore, the results revealed that the addition of D3 improved significantly the composting process performance in terms of steering parameters including the attained temperature, MC and pH. When it comes to the maturity and stability assessment, the decreased profiles of C:N ratio, the nitrification index (NI), as well as the respiration activity (AT4) ascertained the fulfilment of the required conditions for both A1 and A2 to produce stable and mature end-products. However, regarding the compost quality, the examined concentrations of heavy metals met the requirement set by German standards and attested that both A1 and A2 generated highly-qualified products, rated as class B and A, respectively. Furthermore, it is noteworthy to mention that even the AD-effluents which were classified as an “inappropriate substrate” to be inserted to the composters, met the required criteria to be applied directly to land as a highly-qualified liquid biofertilizer. This latter ascertained, additionally, the efficiency and feasibility of the suggested closed cycle for a sustainable FW management. Graphic Abstract

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Section: C:n Ratio Profile During the Composting Processsupporting

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Digestate Post-treatment and Upcycling: Unconventional Moisturizing Agent for Food Waste In-Vessel Composting

Chaher

Nassour

Hamdi

et al. 2021

Waste Biomass Valor

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“…As for the digestate, the BOD 30 to COD ratio is 1:2, indicating that the remaining organics require more adapted biomass and longer retention times for further degradation [14].…”

Section: Biological Oxygen Demandmentioning

confidence: 99%

Anaerobic Digestion of Olive Mill Wastewater and Process Derivatives—Biomethane Potential, Operation of a Continuous Fixed Bed Digester, and Germination Index

Pluschke,

Faßlrinner,

Hadrich

et al. 2023

Applied Sciences

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Olive mill wastewater (OMW) management is an economic and environmental challenge for olive oil-producing countries. The recovery of components with high added value, such as antioxidants, is a highly researched approach that could help refinance performant wastewater treatment systems. Anaerobic (co-)digestion is a suitable process to valorize the energetic and nutritional content of OMW and OMW-derived waste streams from resource recovery processes. Issues of process stability, operation, and yields discourage industrial application. Deepening the understanding of biomethane potential, continuous anaerobic digester operational parameters, and co-substrates is key to large-scale implementation. The biomethane potential of different OMW-derived samples and organic solid market waste as co-substrate was 106–350 NL methane per kg volatile solids (VS). The highest yields were obtained with the co-substrate and depolyphenolized OMW mixed with retentate from an ultrafiltration pretreatment. Over 150 days, an anaerobic fixed-bed 300 L digester was operated with different OMW-derived substrates, including OMW with selectively reduced polyphenol concentrations. Different combinations of organic loading rate and hydraulic retention time were set. The biogas yields ranged from 0.97 to 0.99 L of biogas per g of volatile solids (VS) eliminated, with an average methane content in the produced biogas of 64%. Potential inhibition of the process due to high polyphenol concentrations or over-acidification through volatile fatty acids was avoided in the continuous process through process and substrate manipulation. High concentrations of potassium and low concentrations of nitrogen and phosphate end up in the digestate. Sulfate reduction results in high H2S concentrations in the biogas. The digestate was tested for phytotoxic properties via the germination index. Diluted digestate samples improved germination by up to 50%.

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“…Waste generation is one of the most serious environmental problems facing developing countries globally (Chaher et al, 2020a). Nonetheless, while the anaerobic digestion (AD) of organic waste to biogas is vital to improving energy security, as well as to diversify the energy mix in pursuit of SDG 7, the resulting digestate from the AD process has the potential to be utilized as bio-fertilizer for crop production (SDG 3).…”

Section: Introductionmentioning

confidence: 99%

“…Chaher et al, (2020b) with ve(5) experimental trials as shown in Fig.1.or vegetable waste namely CR, FW, FRW, CR + FW and CR + FW + FRW were respectively co-composted with wood ash and green vegetable waste. The respective ratio of digestate and amendment used are as presented in Table1 Chaher et al, (2020b). with ve (5) experimental trials as shown in Fig.1.…”

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confidence: 99%

Assessment of Aerobic Microbial Activity of Ash and Vegetable-Amended Digestate

Isagba¹,

Ajieh

Oshoma

et al. 2022

Preprint

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Anaerobic digestion (AD) of organic wastes results in biogas and digestate production. The digestate from AD may fall short of vital nutrients required for an optimal plant growth due to feedstock quality. Thus, digestate amendment with biomass and aerobic metabolic activities becomes an essential process for nutrient enhancement. This study aimed to investigate the microbial quality of digestate amended with wood ash, and vegetable matter during treatment. Digestate from cattle rumen (CR), food waste (FW), fruit waste (FRW); and their combinations were obtained. The various digestates were amended with wood ash, vegetable matter and a blend of both. Amendment was carried out for a duration of 5 weeks and samples were analyzed weekly. Enumeration and identification of bacteria and fungi were carried on culture media. The rhizobacterial potential of the identified bacterial isolates was also investigated using standard procedures. The results showed high bacteria and fungal loading in the amended digestate from the first to the fourth week. Comparatively, cattle rumen and food waste digestate, amended with vegetable were highly significant with mean value of 0.8 and 0.6 respectively. The identified bacterial isolates, Bacillus subtilis, Salmonella sp, Pseudomonas sp, Proteus sp, Enterobacter sp, Chromobacterium sp Bacillus spp. and Escherichia coli were found to be involved in solubilization of phosphate, nitrogen fixation, ammonia production and induction of indole acetic acid. Specifically, digestate amended with vegetable waste improved the soil nutrient compared to the wood ash in both bacterial and fungal load. Hence, digestate amendment is crucial for nutrient enhancement, increase in carbon level and overall, improves soil nutrient.

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From anaerobic to aerobic treatment: upcycling of digestate as a moisturizing agent for in-vessel composting process

Cited by 10 publications

References 45 publications

Digestate Post-treatment and Upcycling: Unconventional Moisturizing Agent for Food Waste In-Vessel Composting

Digestate Post-treatment and Upcycling: Unconventional Moisturizing Agent for Food Waste In-Vessel Composting

Anaerobic Digestion of Olive Mill Wastewater and Process Derivatives—Biomethane Potential, Operation of a Continuous Fixed Bed Digester, and Germination Index

Assessment of Aerobic Microbial Activity of Ash and Vegetable-Amended Digestate

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