Processing Of Swine Manure Research Articles

Solid–Liquid Separation and Its Environmental Impact on Manure Treatment in Scaled Pig Farms—Evidence Based on Life Cycle Assessment

Recently, there has been a significant focus on the issue of pollution caused by livestock and poultry rearing, which is recognized as a prominent contributor to nonpoint source pollution in the agricultural sector. This study employed the life cycle assessment (LCA) methodology to evaluate the environmental impact of several pig manure processing scenarios with the aim of determining the appropriate solid–liquid separation tool for large-scale pig farms. The findings indicate that the utilization of a screw extruder for solid–liquid separation in Scenario 2 has a lower environmental impact. In contrast to Scenario 1, Scenario 2 exhibits reduced environmental potential in the areas of global warming, human toxicity, acidification, and eutrophication. Specifically, the global warming, human toxicity, acidification, and eutrophication impacts decreased by 56%, 81%, 83%, and 273%, respectively, due to the implementation of solid–liquid separation. The type of solid–liquid separation equipment used during the processing of swine manure, as well as the subsequent treatment, have a significant impact on environmental emissions. Compared to Scenario 2, Scenario 3, which utilizes a centrifugal microfilter for solid–liquid separation, exhibits a lower environmental impact in terms of human toxicity, resulting in a reduction of 0.736 kg DCB-eq. In general, solid–liquid separation is a viable and environmentally friendly method for the disposal of waste from large-scale pig farms. The adoption of this method is highly recommended. During its implementation, careful consideration should be given to factors such as separation efficiency and pollution emissions. It is crucial to select appropriate equipment for solid–liquid separation to effectively process the waste.

Removal performance and inhibitory effects of combined tetracycline, oxytetracycline, sulfadiazine, and norfloxacin on anaerobic digestion process treating swine manure

Combined veterinary antibiotics (CVAs) belonging to different antibiotics classes could cause exacerbated impacts on the anaerobic digestion (AD) process of swine manure. Four different antibiotics “two tetracyclines: tetracycline (TC) and oxytetracycline (OTC), one fluoroquinolones: norfloxacin (Norf), and one sulfonamides: sulfadiazine (SDZ)” were combined to evaluate their removal performances and its inhibition effects on AD. Results indicated that CVAs removal decreased from 84.3 to 63.7 %, with an increase in the initial concentration from 12.5 to 50 mg L−1, where the removal of CVAs occurring in the order OTC > TC > Norf > SDZ. An average of 9.5, 7.5, 9.5, and 32.1 % of the spiked TC, OTC, SDZ, and Norf were remained in the sludge, respectively. With 50 mg L−1 of CVAs, a competitive adsorption phenomenon was found to have a notable impact on biodegradation microorganisms' activity leading a 73.1 % decrease in CH4 production. CVAs caused a temporal inhibition to the acidogenic activity followed by partial inhibition to methanogenic by 66.8 %, and IC50 was 38.5 mg L−1. Moreover, CVAs resulted in acetate accumulation, while 26 % and 48 % lower in TS and COD removal, respectively, were observed. A significant reduction in the relative abundance of bacteria and archaeal genera was also mentioned. The findings of this research would provide a more in-depth understanding of AD's performance in treating swine manure contaminated with combined antibiotics.

Effects of microbial agents on bacterial community composition during swine manure composting

The process of swine manure and wheat straw aerobic composting was examined, with exogenous microbial agents being added in treatment group. The physicochemical properties were measured by conventional methods, and bacterial community characteristics were investigated by high throughput sequencing analysis. Exogenous microbial agents increased high-temperature duration, reduced pH value at the end of fermentation stage, augmented total nitrogen content, reduced C/N ratio. Results from principal component analysis showed that microbial agents affected the stability of bacterial community during composting. At the phylum level, the relative abundance of Firmicutes, Proteobacteria, and Chloroflexi was higher in the treatment group. At the class level, the relative abundance of Clostridia, Alphaproteobacteria, and Gammaproteobacteria in the treatment group were higher at the mesophilic and thermophilic phases. At the family level, Peptostreptococcaceae, Clostridiaceae_1, and Halanaerobiaceae of the Clostridia and Micromonosporaceae in the treatment group were higher at the mesophilic and thermophilic phases. Halocella was significantly positively correlated with exogenous microbial agents, while Ammoniibacillus was significantly negatively correlated with it. It suggested that microbial agents significantly changed the physicochemical properties and bacterial community structure during swine composting.

Supercritical Ethanol Liquefaction of Swine Manure for Bio-Oils Production

Problem statement: Environmental problems associated with animal waste are the most critical challenges faced by the US intensive confi nement livestock industries. There is an import an d urgent need to develop an efficient way to reduce t he pollution of animal waste while extracting valuable energy. Supercritical liquefaction process ing of swine manure into a liquid fuel was considered as a cost-effective approach for reducin g animal waste in swine farms while simultaneously increasing the farmer's income. Approach: Swine manure was converted to bio-oils by using et hanol as a solvent in an autoclave in the reaction temper ature range of 240-360°C without any catalyst. The effect of reaction temperatures on the bio-oil yiel d and properties was investigated. The oil product was evaluated by Fourier Transform Infrared spectro scopy (FTIR), elemental analyses, heating values, water content analyses, ash content and solids cont ent. Results: The experimental results show that the yield of the liquefaction products was significantl y influenced by the reaction temperature. The maximum oil yield of 26.7% (of dry matter) with low content of oxygen (11.48%) and heating value of 33.98 MJ kg -1 was obtained at reaction temperature of 300°C. A l ow content of carbonyl and aliphatic groups and a high aromaticity in the bio-oil were f ound in the bio-oils from high temperature as determined by FTIR. The elemental composition of the bio-oil samples changes with reaction temperature. However, no particular trends in the elemental composition were found within the range of reaction temperature used. Conclusion: This research proved that supercritical ethanol li quefaction was an effective way to remove oxygen and utilize c arbon and hydrogen in swine manure to produce energy condensed bio-fuel. Further work is needed t o optimize the bio-oil production process in terms of oil yield and oil quality.

Comparison of saccharification process by acid and microwave-assisted acid pretreated swine manure

The saccharification process of swine manure by conventional and microwave-assisted acid pretreated were investigated using cellulose enzymes, respectively. The optima for microwave-assisted acid pretreated swine manure is achieved when swine manure of 50 g l(-1) of substrate concentration and water amount 40 ml was pretreated by 4% H2SO4 concentration with 445 W microwave powers for 30 min at pretreatment period, and temperature 50 degrees C, enzyme loading 2 mg g(-1) substrate, substrate concentration 5 g l(-1) and initial medium pH 4.8 at enzymes hydrolysis period by microwave-assisted acid pretreated, respectively. The optimal conditions by conventional acid pretreated is obtained when 50 g l(-1) swine manure was submerged in 40 ml, 4% H2SO4 maintained at 130 degrees C for 3 h at pretreatment period, and temperature 45 degrees C, enzyme loading 2 mg g(-1) substrate, substrate concentration 15 g l(-1) and initial medium pH 5.2 at enzymes hydrolysis period, respectively. Under the optimum conditions microwave-assisted acid pretreatment could achieve higher yield of reducing sugar, short reaction time, and lower energy consumption than from the conventional acid pretreatment, which indicates that microwave-assisted acid pretreatment is more suitable for swine manure pretreatment than by acid alone.