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In this study, ultrasound (US) disintegration was evaluated as a digestate treatment strategy. Digestate treatment is the physical, chemical or biological treatment and recirculation AD of the effluents of the anaerobic digesters (i.e., digestate) to the digester as supplementary feed to increase their utilization potential for energy conversion or green chemical production in post-valorization pathways. In this scope, semi-continuous small pilot scale manure digesters were operated in parallel with various operational settings. One of the digesters was fed by adding disintegrated digestate to an equal volume of fresh manure feed (recycle ratio of 1). The obtained results showed that US-assisted digestate treatment at 1500 kJ/kg TS specific energy input with 30 days of hydraulic retention time increased the methane production rate by 18%. The increased methane production rate was found to be related to the applied specific energy and organic loading rate. A basic cost-benefit analysis showed that the energy demand of the US disintegration at lab scale was higher than the energy that can be recovered from the additional biogas produced.

ispartof: FUEL vol:291 status: published

Digestate treatment techniques have recently been proposed as a strategy to increase the ultimate biogas yield from dairy manure and to improve the digestate quality as an organic fertilizer. These studies however rarely take the trace elements (TE) and nutrient partitioning into account. This study focusses on ozone treatment (5–40 g O3 kg−1 Total Solids (TS)) as a digestate treatment technique to control the concentration of TE and nutrients in the liquid phase of the digestate. Controlling the TE and nutrient concentrations in the liquid and solid digestate can improve the agronomic value of dairy manure digestate. The ozone concentration of the gas stream entering reactor was 48.53 g O3/Nm³ or 3.4% w/w O3 in O2-gas. The experiments were repeated using pure oxygen gas to investigate its influence. The results from ozonation and oxygenation of the dairy manure digestates revealed that O3 treatment up to 40 g O3 kg−1 TS did not have a more pronounced effect on the biochemical parameters compared to supplementation of pure O2. Ozonation of the digestate and the supernatant showed that the TE concentration in the liquid phase followed a parabolic profile. The observed initial increase in this parabolic profile was explained by the release of TE from the organic matter to the supernatant causing an increase in TE concentration, followed by a decrease due to precipitation of TE as hydroxides and sulfides, due to the increasing pH and sulphur concentrations. ispartof: Chemosphere vol:252 ispartof: location:England status: Published online

Recently, digestate disintegration gained interest as an alternative strategy to feedstock pretreatment for anaerobic digestion. This study evaluated the effect of three different digestate disintegration methods (hydrogen peroxidation, ozone treatment and ultrasound) on manure digestate, potato waste digestate and mixed organic waste digestate. Lab-scale anaerobic digestion experiments were carried out by adding disintegrated digestate to the related substrate and inoculum with simulated recycle ratios of 0.2 and 0.5. Ultrasound disintegration of potato waste digestate yields 22.5% increase in biogas production. An increase in biogas production was linked to the treated digestate amount and the treatment dosage. First order model was used to investigate the effect of digestate disintegration on the first order reaction rate constant (k). The decrease in k and increase in biogas production were linearly correlated. This correlation was explained by the increased bioavailability of the organic matter and possible negative effects of digestate disintegration on the microorganisms. ispartof: BIORESOURCE TECHNOLOGY vol:268 pages:568-576 ispartof: location:England status: published

Substantial insight into the effect of ultrasound disintegration on the changes in biochemical parameters of manure digestate and digestate age is needed to understand the potential of digestate treatment. To address this knowledge gap, in this study, the effect of digestate age on the efficiency of ultrasound (US) disintegration was investigated. In this scope, dairy manure digestate samples were incubated in an oven at 37 °C for a predetermined amount of time to obtain simulated digestate ages of 15, 22, 29, 36 and 43 days. The results showed that US disintegration efficiency significantly affected the initial biochemical characteristics of digestate and that the digestate age had a significant effect on the US disintegration efficiency. This effect diminished when the applied specific energy (SE) was higher than 3000 kJ/kg total solids (TS). A numerical partial least squares (PLS) model was constructed to investigate the relative influences of the initial biochemical parameters on the soluble chemical oxygen demand (sCOD) and soluble carbohydrates (sCARB) solubilization. The results of the high-quality (R2 = 0.8) model indicated that the most influential parameters for the efficiency of US disintegration were the SE, the initial sCARB0, the TS, the initial sCOD0 and the volatile solids (VS).

During last decades, concentration of human and veterinarian antibiotics in the environment, natural and engineered systems have been increased because of high amount production and consumption. This situation has aroused great concern due to the possibility of harmful effects on human, animals and plants [1,2]. Occurrence and fate of these compounds are one of the main issues because of their unknown potential risks and their effects on the environment. Approximately 500 tonnes of them are produced and consumed every year in the worldwide. Antibiotics are resistant to conventional biological treatment process and the wastewaters including these compounds are directly discharged to the receiving water bodies without efficient treatment. Hospitals and pharmaceutical industries are the main sources of high antibiotic concentration release to the environment [3]. Also sewage systems can transport these molecules and/or their metabolites since metabolization of them by humans and animals cannot be achieved completely [4]. During the transportation of antibiotics throughout treatment plants, elimination of these compounds can occur via biodegradation, photolysis and sorption to sludge but ultimate degradation of these compounds cannot be achieved in conventional treatment plants [4, 5, 6]. As a result of the introduction of metabolized and/or active antibiotics to the receiving water bodies caused an increase in the ratio of multiantibacterial resistant pathogens [7].