Production of compost from logging residues.

The implementation of forest management generates logging residue which can be used in several ways. One of the option is to use of logging residue in the composting process. Therefore, this study determined the possibility of producing compost based on logging residue and the produced fertilizer used to fertilize forest nurseries. Pine chips and sewage sludge were used for carrying out the study. The compost, as well as the leachate produced during composting, were characterized by high NPK content. The leachate collected at the end of the experiment was characterized by nitrogen content of approximately 6500 mg‧dm-3, phosphorus of approximately 450 mg‧dm-3, and potassium of approximately 500-700 mg‧dm-3. In contrast, the compost produced contained approximately 0.57 g‧kg-1 nitrogen, approximately 0.39 g‧kg-1 phosphorus, and approximately 0.24 g‧kg-1 potassium. The disadvantage in terms of the usefulness of the resulting fertilizer in forest nurseries is its pH, which exceeded 9.0.

Enhanced methanogenic performance and metabolic pathway of high solid anaerobic digestion of chicken manure by Fe2+ and Ni2+ supplementation.

High solid anaerobic digestion (AD) is a promising technology for the treatment of organic waste in terms of efficient bioenergy production and digestate volume reduction. However, the high solid AD of chicken manure has been a challenge due to the inhibition effects caused by high ammonia levels. In this study, the addition of 280 mg/L Fe2+ and 2 mg/L Ni2+ has been proven to enhance the microbial activity and to overcome inhibition under the stressed environment. The mesophilic digesters feeding with total solid around 150 g/kg operated at an organic loading rate of 4.8 g/(L d) based on volatile solid and a 20-day hydraulic retention time. The total ammonia-nitrogen reached around 6.8 g/L in control and Fe-Ni digesters. The results from the 147-day continuously-fed experiment provided an increment of 34% methane production and a 29% reduction of volatile fatty acids against control. The acetoclastic and hydrogenotrophic methanogenic activity was increased by 89% and 40% respectively. The high throughout sequencing results showed an increased percentage of Methanosarcina sp., which may have contributed to the shifting of the methanogenic pathway towards acetoclastic methanogenesis. The positive effects of Fe2+ and Ni2+ supplementation obtained in this study lay the foundation for its use in AD of nitrogen rich materials.

An effective method of utilizing vegetable waste in the form of carriers for Trichoderma strains with phytosanitary properties.

It has been assumed that compost from savoy cabbage and rapeseed straw is a good substrate for discrimination of the reproduction potential of Trichoderma strains. This hypothesis was verified based on a two-stage incubation experiment. The prepared mixture was fermented in a bio-reactor for 11 weeks. In the second experiment, the mature compost was inoculated with four strains of Trichoderma and a spore concentration of 104 and 106, and then incubated for four weeks. The biomass of autogenic fungi reached a maximum of 12.5 mg∙g-1 DM in the cooling phase. The variability in temperature during composting significantly affected NH3 emission. The pH of mature compost from cabbage wastes, as a result of the elevated NH3 emission reached the alkaline range. The survival of the Trichoderma fungi introduced into the alkali substrate was a result of strain sensitivity to the high pH of the compost and to the initial inoculum density. The adaptation potential of Trichoderma harzianum to the alkali milieu depended on the pH stabilization of the substrate by this fungi, provided the spore inoculum density was 106. The strains of Trichoderma atroviride responded negatively, regardless of the inoculum density, to the alkaline pH of the substrate and to self-induced changes in the compost pH.

Biochar to reduce ammonia emissions in gaseous and liquid phase during composting of poultry manure with wheat straw.

Composting of poultry manure which is high in N and dense in structure can cause several problems including significant N losses in the form of NH3 through volatilization. Biochar due to its recalcitrance and sorption properties can be used in composting as a bulking agent and/or amendment. The addition of a bulking agent to high moisture raw materials can assure optimal moisture content and enough air-filled porosity but not necessarily the C/N ratio. Therefore, amendment of low C/N composting mixtures with biochar at low rates can have a positive effect on composting dynamics. This work aimed at evaluating the effect of selected doses of wood derived biochar amendment (0%, 5% and 10%, wet weight) to poultry manure (P) mixed with wheat straw (S) (in the ratio of 1:0.4 on wet weight) on the total ammonia emissions (including gaseous emissions of ammonia and liquid emissions of ammonium in the collected condensate and leachate) during composting. The process was performed in 165L laboratory scale composting reactors for 42days. The addition of 5% and 10% of biochar reduced gaseous ammonia emission by 30% and 44%, respectively. According to the obtained results, the measure of emission through the condensate would be necessary to assess the impact of the total ammonia emission during the composting process.

Preliminary study of acrylamide monomer decomposition during methane fermentation of dairy waste sludge.

Polyacrylamide (PAM) used in sludge dewatering exists widely in high-solid anaerobic digestion. Acrylamide is registered in the list of chemicals demonstrating toxic, carcinogenic and mutagenic properties. Therefore, it is reasonable to ask about the mobility of such residual substances in the environment. The study was carried out to assess the impact of the mesophilic (39±1°C) and thermophilic (54±1°C) fermentation process on the level of acrylamide monomer (AMD) content in the dairy sludge. The material was analysed using high-performance liquid chromatography (HPLC) for quantification of AMD. The results indicate that the process of methane fermentation continues regardless of the temperature effects on the degradation of AMD in dairy sludge. The degree of reduction of acrylamide monomer for thermophilic fermentation is 100%, while for mesophilic fermentation it is 91%. In practice, this means that biogas technology eliminates the risk of AMD migration to plant tissue. Moreover, it should be stressed that 90% of cumulative biogas and methane production was reached one week earlier under thermophilic conditions - the dynamics of the methanisation process were over 20% faster.

Integrated approach to sustain biogas production in anaerobic digestion of chicken manure under recycled utilization of liquid digestate: Dynamics of ammonium accumulation and mitigation control.

The dynamics of ammonium accumulation and mitigation control in anaerobic digestion of chicken manure under the recycled utilization of liquid digested slurry were investigated by using an integrated approach in two laboratory-scale semi-continuously stirred tank reactors. In the reactor with direct recycled utilization of the anaerobic digested liquid slurry, total volatilized fatty acids (in CH3COOH) and NH4(+)-N increased from 1600mg/L to 8000mg/L and from 2600mg/L to 5000mg/L, respectively. The daily volumetric biogas production decreased from 1.4±0.1L/(L·d) to 0.8±0.1L/(L·d) with a reduction efficiency of 43±4%. Air stripping was integrated for ammonium mitigation of recycled liquid digested slurry and was shown to effectively reduce the ammonium to 3000mg/L. Correspondingly, the biogas production was recovered back to 1.4±0.1L/(L·d). This indicated the potential of the integration of air stripping for ammonium mitigation in an anaerobic digestion process with liquid digested slurry recirculation.

Co-composting of poultry manure mixtures amended with biochar - The effect of biochar on temperature and C-CO2 emission.

Biochar as an amendment could have an impact on composting dynamics. This study investigated the effect of the addition of biochar (B) to poultry manure (P) mixed with wheat straw (S) (i.e. P:S, P:S+5%B and P:S+10%B) on temperature and carbon dioxide emission. For temperature studies a modified equation for net degree-hour parameter DHnet (°Chday(-1)) was proposed. The modified equation takes into account ambient temperature. The highest daily temperatures DHnet were observed on day 2 and the mixture with the highest addition of biochar (P:S+10%) reached the max temperature. The period of thermophilic temperatures (40°C>) was shorter for mixtures amended with biochar. The addition of biochar increased C-CO2 emission and the total C-CO2 emission were higher about 6.9% and 7.4% for P:S+5%B and P:S+10%B, respectively.

The kinetics of nicotine degradation, enzyme activities and genotoxic potential in the characterization of tobacco waste composting.

This study aimed to determine nicotine biodegradation and the genotoxic potential of nicotine and its degradation products during the process of tobacco waste composting. Composting was carried out using two methods, i.e. the addition of 20% (bioreactor A) or 40% tobacco wastes to sewage sludge (bioreactor B) and control--sewage sludge (bioreactor C). Wheat straw was used as a structure-forming material. As a result of composting the contents of C and N in the bioreactors changed, the C:N ratio in bioreactor A changed from 22.8 to 13.00, and that in bioreactor B changed from 23.5 to 12.00. After composting, the biodegradation rate of nicotine was 78% in bioreactor A and 80% in bioreactor B, respectively. Using the Ames test it was shown that the composts produced did not exhibit mutagenicity.