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International audience; An experimental design was proposed to test the influence of three parameters on the performance of food waste (FW) dry anaerobic digestion (AD) coupled with aerobic pre-treatment: (1) the type of aerobic pre-treatment (no pre-treatment/dynamic aeration/static storage); (2) the composition of FW (paper/no paper) and (3) the frequency of leachate recirculation in the batch leach bed reactor (LBR) used as dry AD process. Performance of AD was assessed by measuring pH, VFA, biogas production and by modelling the kinetics of methane production using modified Gompertz equation. A statistical analysis of variance showed that AD leachate recirculation condition was the most impacting parameter on methane production. A high production of VFA was noticed (~ 25 gDCO·L '1 ) that did not lead to inhibition due to high buffer capacity of inoculum (5.2 gN-NH 4 + ·L '1 ). 80% of the biomethane potential was reached in the batch test with a daily leachate recirculation and with FW without paper. According to simulations, an experimental duration of 31'32 days showed to be optimal to reach 90% of degradation potential under these LBR conditions. A lower frequency of leachate recirculation or the addition of paper decreased methane production. The introduction of a two-day aeration step stabilized the production of VFA along the digestion process and enhanced the methane production on FW with paper. Conversely a two-day storage step induced a rapid acidification and a subsequent significant decrease of methane production rate. © 2019, Springer Nature B.V.

A reactor for whole blood sampling integrated with instant protein digestion in a “lab-on-paper” format is introduced here. The sampling reactor was fabricated on commercially available filter paper using 2-hydroxyethyl methacrylate-co-2-vinyl-4,4-dimethyl azlactone (HEMA-VDM) polymerization followed by the immobilization of trypsin. Immobilization conditions were investigated with respect to temperature, enzyme amount and immobilization time. The highest reactor efficiency with respect to protein digestion was obtained with 1.25 mg trypsin per reactor immobilized at room temperature for 3 hours. Commercially available cellulose filter papers and DMPK-C cards were modified and immobilized with trypsin prior to whole blood sampling. Filter paper specifications including thickness (180–220 μm), weight (77–92 g m−2) and porosity (11–25 μm) were investigated with respect to performance (digestion efficiency and extraction recovery). From this study, it was found that a medium thickness paper with higher weight and porosity is optimal for reactor efficiency. The reactors were tested and compared with respect to a standard dried blood spot procedure for protein digestion. The most efficient reactors obtained 134 ± 14 and 124 ± 7 high confidence protein groups for freeze thawed and fresh whole blood samples, respectively.

The effects of lime mud from papermaking process (LMP) addition as buffer agent and inorganic nutrient on the anaerobic digestion stability of food waste (FW) were investigated under mesophilic conditions with the aim of avoiding volatile fatty acids accumulation, and inorganic elements deficiency. When LMP concentration ranged from 6.0 to 10g/L, the FW anaerobic digestion could maintain efficient and stable state. These advantages are attributed to the existence of Ca, Na, Mg, K, Fe, and alkaline substances that favor the methanogenic process. The highest CH4 yield of 272.8mL/g-VS was obtained at LMP and VS concentrations of 10.0 and 19.8g/L, respectively, with the corresponding lag-phase time of 3.84d and final pH of 8.4. The methanogens from residue digestates mainly consisted of Methanobrevibacter, coccus-type and sarcina-type methanogens with LMP addition compared to Methanobacteria in control. However, higher concentration of LMP inhibited methanogenic activities and methane production.

International audience; Dry anaerobic digestion is a promising option for food waste treatment and valorization. However, accumulation of ammonia and volatile fatty acids often occurs, leading to inefficient processes and digestion failure. Co-digestion with cardboard may be a solution to overcome this problem. The effect of the initial substrate to inoculum ratio (0.25 to 1 gVS·g VS−1) and the initial total solids contents (20–30%) on the kinetics and performance of dry food waste mono-digestion and co-digestion with cardboard was investigated in batch tests. All the conditions produced methane efficiently (71–93% of the biochemical methane potential). However, due to lack of methanogenic activity, volatile fatty acids accumulated at the beginning of the digestion and lag phases in the methane production were observed. At increasing substrate to inoculum ratios, the initial acid accumulation was more pronounced and lower cumulative methane yields were obtained. Higher amounts of soluble organic matter remained undegraded at higher substrate loads. Although causing slightly longer lag phases, high initial total solids contents did not jeopardize the methane yields. Cardboard addition reduced acid accumulation and the decline in the yields at increasing substrate loads. However, cardboard addition also caused higher concentrations of propionic acid, which appeared as the most last acid to be degraded. Nevertheless, dry co-digestion of food waste and cardboard in urban areas is demonstrated as an interesting feasible valorization option.

The aim of the present study is to evaluate the probiotic attributes of Bacillus subtilis AMS6 isolated from fermented soybean (Churpi). This isolate exhibited tolerance to low pH (pH 2.0) and bile salt (0.3%), capability to autoaggregate and coaggregate. AMS6 also showed highest antibacterial activity against the pathogenic indicator strain Salmonella enterica typhimurium (MTCC 1252) and susceptibility towards different antibiotics tested. The isolate was effective in inhibiting the adherence of food borne pathogens to Caco-2 epithelial cell lines, and was also found to be non-hemolytic which further strengthen the candidature of the isolate as a potential probiotic. Further studies revealed B. subtilis AMS6 showed cellulolytic activity (0.54±0.05 filter paper units mL(-1)) at 37°C. The isolate was found to hydrolyze carboxymethyl cellulose, filter paper and maize (Zea mays) straw. The maize straw digestion was confirmed by scanning electron microscopy studies. The isolate was able to degrade filter paper within 96h of incubation. A full length cellulase gene of AMS6 was amplified using degenerate primers consisting of 1499 nucleotides. The ORF encoded for a protein of 499 amino acids residues with a predicted molecular mass of 55.04kDa. The amino acids sequence consisted of a glycosyl hydrolase family 5 domain at N-terminal; Glycosyl hydrolase catalytic core and a CBM-3 cellulose binding domain at its C terminal. The study suggests potential probiotic B. subtilis AMS6 as a promising candidate envisaging its application as an animal feed additive for enhanced fiber digestion and gut health of animal.

In a lab-scale upflow anaerobic sludge blanket reactor inoculated with granular sludge from a full-scale wastewater treatment plant treating paper mill wastewater, methanethiol (MT) was degraded at 30°C to H 2 S, CO 2 , and CH 4 . At a hydraulic retention time of 9 h, a maximum influent concentration of 6 mM MT was applied, corresponding to a volumetric loading rate of 16.5 mmol liter −1 day −1 . The archaeal community within the reactor was characterized by anaerobic culturing and denaturing gradient gel electrophoresis analysis, cloning, and sequencing of 16S rRNA genes and quantitative PCR. Initially, MT-fermenting methanogenic archaea related to members of the genus Methanolobus were enriched in the reactor. Later, they were outcompeted by Methanomethylovorans hollandica , which was detected in aggregates but not inside the granules that originated from the inoculum, the microbial composition of which remained fairly unchanged. Possibly other species within the Methanosarcinacaea also contributed to the fermentation of MT, but they were not enriched by serial dilution in liquid media. The archaeal community within the granules, which was dominated by Methanobacterium beijingense , did not change substantially during the reactor operation. Some of the species related to Methanomethylovorans hollandica were enriched by serial dilutions, but their growth rates were very low. Interestingly, the enrichments could be sustained only in the presence of MT and did not utilize any of the other typical substrates for methylotrophic methanogens, such as methanol, methyl amine, or dimethylsulfide.

In situ experiments and two lamb digestion trials were conducted to evaluate the effects of chemically treating recycled newsprint (NP). Treatment of NP with 2% HCl (percentage of NP DM) followed by autoclaving for 4 h was most efficacious and was used in an in vivo digestion trial with 25 ram and wether lambs in a randomized complete block design (RCB). On a DM basis treatment diets were: 1) control, 95% alfalfa hay (AH); 2) 75% AH, 20% HCl-treated NP (HCl-NP); 3) 55% AH, 40% HCl-NP; 4) 75% AH, 20% untreated NP; and 5) 55% AH, 40% untreated NP on a DM basis. Lambs fed Treatments 2 and 3 had ad libitum DMI (1,043 and 1,036 g/d, respectively) similar to the DMI of those fed the control treatment (1,024 g/d); however, lambs fed Treatments 4 and 5 had lower (P < .05) ad libitum DMI (578 and 426 g/d, respectively) than lambs fed Treatments 1, 2, and 3. Apparent DM digestibilities were lower (P < .05) by lambs consuming Treatments 2, 3, 4, and 5 (52.6, 44.5, 52.0, and 48.2%, respectively) than by those consuming Treatment 1 (60.7%). Apparent OM, CP, NDF, and ADF digestibilities followed trends similar to DM. In the second digestion trial, 15 ram and wether lambs were used in a RCB to compare Treatments 1, 2, and 3. For this second digestion study, NP was treated with 4% HCl (percentage of NP DM), autoclaved for 4 h, and diets were fed at 2% of BW. As in Trial 1, apparent nutrient digestibilities decreased (P < .05) with increasing amounts of HCl-NP. Our results suggest that HCl-NP can be fed to sheep at 40% of the diet without a decrease in DMI; however, apparent nutrient digestibility decreases with increasing levels of HCl-NP.

A method is described for the determination of cadmium in pulp and paper and the results of an interlaboratory test are also given. The test solutions are prepared by pressurized digestion with conc. nitric acid in a PTFE crucible. The traces of cadmium are determined by AAS. With this method, and using 1 g samples, it is possible routinely to prove the presence of cadmium with a limit of 10 myg Cd/kg sample.

Eleven papers were compared for absorption of whey and for digestibility in vitro. Papers were squared, ground, and soaked in whey for 1,5, and 15 min and for 1, 6, 24, 48, and 72 h. Digestibility in vitro was determined on minimum and maximum whey absorption of each squared and ground paper sample. Whey absorption by squared papers increased with time. Ground samples absorbed more whey than squared ones and maximum quantities were absorbed within 1 to 5 min. Mean percent absorptions for ground telephone book covers, glossy magazines, computer cards, computer printout sheets, daily newsprint, telephone directory yellow pages, cardboard box, feedsacks, brown bags, telephone directory white pages, and coasters were: 31.0, 35.2, 35.4, 36.5, 43.9, 47.9, 51.0, 51.4, 51.7, 55.6, and 67.4. For seven papers, addition of whey increased digestibility. Four papers were either unchanged or decreased in digestibility. This depression of digestibility may have resulted from the high fat content of whey used. Based on in vitro digestibilities, we conclude that it is possible to recycle selected paper/whey combinations through ruminants.

Extensive digestion of the basic trypsin inhibitor by thermolysin at 60–80° has been demonstrated by loss of inhibitory activity, increase in ninhydrin positive material and separation of the breakdown products by electrophoresis. Formation of the inhibitor-trypsin complex does not protect the inhibitor from digestion by thermolysin; both components are digested. Between 40° and 80° the inhibitor undergoes a reversible transition involving a slight conformational change; this may account for its susceptibility to thermolysin.