Evaluation of Poultry Manure: Combination of Phosphorus Recovery and Activated Carbon Production

Circular economy approach: Nutrient recovery and economical struvite production from wastewater sources by using modified biochars

The enrichment of phosphorus (P) and nitrogen (N) in aquatic systems can cause eutrophication. Moreover, P rocks may become exhausted in the next 100 years. A slow-release fertilizer called struvite (MgNH4PO4.6H2O) can reduce surface runoff. However, the high cost of raw material or chemicals is a bottleneck in their economical production. Therefore, incinerated sewage sludge ash, food wastewater, and bittern were combined as the sources of P, N, and Mg, respectively. Sawdust biochar was used to enhance the adsorptive recovery of nutrients. First, recovery kinetics was studied by comparing bittern-impregnated biochar (BtB) with the Mg-impregnated biochar (MgB). Subsequently, the synergistic physical and chemical interactions were observed for P and N recovery. Almost complete PO43-P recoveries were achieved within 10 min for both biochars. However, NH4+-N recovery was stable after 2 h, with 26% recovery by MgB and 20% recovery by BtB. Biochars activated with steam (steam-activated biochar) and KOH (KOH-activated biochar) gave superior activities to those of unactivated biochars and activated carbon (AC) nutrient recovery and struvite purity. Moreover, the activated biochars showed a lower risk of surface runoff, similar to that of AC. Therefore, activated biochars can be used as an alternative to AC for economical struvite production from a combination of wastewater sources.

Effect of wood and peanut shell hydrochars on the desiccation cracking characteristics of clayey soils

Soil cracking can significantly alter the water and nutrient migration pathways in the soil, influencing plant growth and development. While biochar usage has effectively addressed soil cracking, the feasibility of using less energy-intensive hydrochars in desiccating soils remains unexplored. This study investigates the impact of wood and peanut shell hydrochars on the desiccation cracking characteristics of clayey soil. A series of controlled environmental laboratory incubations with regular imaging was conducted to determine crack development's dynamic in unamended and hydrochar-amended soils. The results reveal that the addition of wood hydrochar at 2% and 4% dosage reduced the crack intensity factor (CIF) by 22% and 43%, respectively, compared to the unamended control soil. Similarly, the inclusion of peanut shell hydrochar at 2% and 4% lowered the CIF by 22% and 51%, respectively. The presence of hydrophilic groups on the surface of hydrochars, such as O-H, CH, and C-O-C, enhanced the water retention capacity, as confirmed by Fourier-transform infrared analysis. The CIF decrease is attributed to mitigated water evaporation rates, enabled by enhanced water retention within the hydrochar pore spaces. These findings are supported by scanning electron microscopy analyses of the hydrochar morphology. Despite CIF reduction with hydrochar incorporation, the crack length density (CLD) increased across all hydrochar-amended series. In contrast to unamended soil which exhibited pronounced widening of large cracks and extensive inter-pore voids, the incorporation of hydrochar resulted in higher CLD due to the formation of finer interconnecting crack meshes. Consequently, the unamended control soil suffered greater water loss due to heightened evaporation rates. This study sheds new light on the potential of hydrochars in addressing desiccation-induced soil cracking and its implications for water conservation.

Nutrient release pattern and mitigation of N2O emissions under the application of activated poultry manure compost biochar with organic resources

Biochar was generally used to reduce the macronutrient releases and to mitigate N2O gas emissions in cropland. This experiment evaluated the trend of major plant nutrient releases using the modified Hyperbola model and the greenhouse gas emissions by incorporating different poultry manure compost biochar with organic resources. The treatments consisted of the control as the organic fertilizer materials, the incorporated poultry manure compost biochar with organic fertilizer materials (PMCBF), and the incorporated plasma-activated poultry manure compost biochar with organic fertilizer materials (PAMBF) under redox conditions. The results showed that the cumulated highest concentrations of NH4-N and NO3-N were 2168.6 mg L-1 and 21.7 mg L-1 in the control, respectively. Compared with the control, the predicted reduction rates of NH4-N release from the PMCBF and PAMBF were 26.2% and 15.4%, respectively. In the control, the cumulated highest concentrations of PO4-P and K in leachate were 681.04 mg L-1 and 120.5 mg L-1, respectively. The predicted reduction rates of PO4-P and K were 55.1% and 15.5%, respectively, under the PAMBF compared to the control. The modified Hyperbola model with cumulated NH4-N, PO4-P, and K-releases under the treatments was a good fit (p < 0.0001). For greenhouse gas (GHG) emissions, the lowest cumulative N2O was 59.59 mg m-2 in the soil incorporated with PMCBF, and its reduction rate was 23.5% compared with the control. The findings of this study will contribute to more profound insights into the potential application of PAMBF and PMCBF as bio-fertilizers adapted to mitigate NH4-N, PO4-P, and K releases and N2O emissions, offering scientific evidence for organic farming strategies.

Changes in the nutrient profile and the load of mycotoxins, phytoestrogens, and pesticides in horse pastures during spring and summer in Austria

Pastures are used for grazing and the production of conserved roughage in horses. Yet, the nutritional profile of the forage varies from spring to late summer, affecting equine nutrient supply and health. In addition, environmental factors may also favor plant contaminants such as mycotoxins. This study aimed to determine the nutritional profile and contaminant load of selected horse pastures from early spring till late summer. The nutrient composition (main macronutrients, macro elements and trace elements), as well as mycotoxins, metabolites, pesticides, and plant-derived compounds of seven horse pastures were analyzed. Each pasture was sampled three times and the samples were categorized according to the status of the pasture plants: ear emergence, early- till full bloom, and drought-damaged vegetation. Drought-damaged pastures demonstrated a rise in the acid to neutral detergent fiber ratio, calcium, iron, and magnesium but lower potassium contents. Mycotoxins and other contaminants were found in the pastures including 64 fungal compounds (ergot alkaloids (13) and metabolites from Fusarium (21), Aspergillus (2), Penicillium (8), Alternaria (8) and other fungal species (12), one bacterial metabolite (cereulide), twelve plant metabolites (including eight phytoestrogens and three cyanogenic glycosides (linamarin, lotaustralin and prunasin)), 11 nonspecific metabolites and six pesticides. Fusarium metabolites showed the highest concentrations among the fungal metabolites and drought-induced stress increased the contamination levels (range: 123-3873 µg/kg DM). In conclusion, there was a dominant effect of the developmental stages of the plants, botanical composition of the pastures and weather conditions on the nutritional composition and presence of contaminants on pastures.