Evaluation of Brazilian potential for generating electricity through animal manure and sewage

This paper reviews the chemical hydrolysis processes of dairy manure fiber to make its sugar accessible to microorganisms during anaerobic digestion and identifies obstacles and opportunities. Researchers, so far, investigated acid, alkali, sulfite, and advanced oxidation processes (such as hydrogen peroxide assisted by microwave/ultrasound irradiation, conventional boiling, and wet oxidation), or their combinations. Generally, dilute acid (3–10%) is less effective than concentrated acid (12.5–75%), which decrystallizes the cellulose. Excessive alkaline may produce difficult-to-degrade oxycellulose. Therefore, multi-step acid hydrolysis (without alkaline) is preferred. Such processes yielded 84% and 80% manure-to-glucose and -xylose conversion, respectively. Acid pretreatment increases lignin concentration in the treated manure and hinders subsequent enzymatic processes but is compatible with fungal cellulolytic enzymes which favor low pH. Manure high alkalinity affects dilute acid pretreatment and lowers glucose yield. Accordingly, the ratio of manure to the chemical agent and its initial concentration, reaction temperature and duration, and manure fineness need optimization because they affect the hydrolysis rate. Optimizing these factors or combining processes should balance removing hemicellulose and/or lignin and increasing cellulose concentrations while not hindering any subsequent process. The reviewed methods are neither economical nor integratable with the on-farm anaerobic digestion. Economic analysis and energy balance should be monolithic components of the research. More research is required to assess the effects of nitrogen content on these processes, optimize it, and determine if another pretreatment is necessary.

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“…Unfortunately, livestock manure is still an undervalued and unexploited source of clean and renewable energy. [16] Note: NR = not reported.…”

Section: Introductionmentioning

confidence: 99%

Chemical Methods for Hydrolyzing Dairy Manure Fiber: A Concise Review

2021

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“…The biogas generated is burned in flares (Fig. [1][2][3][4][5][6][7][8][9][10][11] [24]. Finally, the CLB's main source of heat is the incident solar radiation on the top of the biodigester (Fig.…”

Section: Base Scenario For Pig Farms Using Covered Lagoon Biodigestersmentioning

confidence: 99%

“…3-13); (ii) burning in a motor generator to generate electricity (Fig. [3][4][5][6][7][8][9][10][11][12][13][14]; and (iii) fuel generation (Fig. 3-15).…”

Section: Improved Pig Farm Base Scenario Flowchartsmentioning

confidence: 99%

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Insights to improve covered lagoon biodigesters through by-products recovery in pig farms

Almeida

Oliveira

Sousa

et al. 2021

Environmental Research and Technology

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Pig farming activity has an important role in the Brazilian economy and generates effluents with a high polluting potential. The covered lagoon biodigester is a simple and suitable alternative for the treatment of swine manure. This work aimed to propose improvements to the pig effluent treatment system composed by covered lagoon biodigesters. Therefore, a survey of a typical plant configuration of pig effluent treatment was accomplished and alternatives were suggested in order to get a greater energy sustainability in farms through resource recovery. The proposed interventions were based on studies of scientific papers, technical equipment manuals, technical research and consultation with professionals of the field. Th e op timization of the systems operation considers some criteria, such as: (i) need for solids removal; (ii) organic loading; (iii) operation temperature; (iv) effluent recirculation; and (v) biogas energy recovery. Firstly, a typical scenario was identified without any improvements, in which the biogas is sent to flares without energy recovery. Subsequently, systems improvement insights were proposed, mainly regarding effluent heating through a solar heating system or by recovering the thermal energy from biogas and biogas recovering. The treatment optimization would increase the efficiency of organic matter re moval and bi ogas production, as well as el ectric energy production and reduction in greenhouse gases emissions. The use of tools such as Life Cycle Analysis (LCA) can favor decision making and comparing proposed alternatives.

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“…At present, the treatment of livestock and poultry manure includes mainly physical methods [sedimentation ( 3 ), filtration ( 4 ), dry and wet separation ( 5 ), and high-temperature drying ( 6 )], chemical methods [precipitation ( 7 ), flocculation ( 8 ), and advanced oxidation processes ( 9 )], and biochemical methods [aerobic ( 10 ) and anaerobic fermentation ( 11 )]. Among these methods, anaerobic fermentation has been receiving large attention for being simple, inexpensive, and environment friendly ( 12 ).…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Risk Assessment of Applying Biogas Slurry in Peanut Cultivation

et al. 2021

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Biogas slurry, a byproduct of biogas plants, is considered a high-quality bio-organic fertilizer. Despite providing nutrients to crops, biogas slurry may contain a high concentration of heavy metals, leading to food safety problems and endangering human health if such metals are absorbed by plants. Therefore, biogas slurry should undergo systematic risk assessment prior to direct use on farmland to ensure its safety for soils and crops. In this study, the risk of applying biogas slurry in peanut cultivation was comprehensively evaluated. Based on nitrogen contents, different concentrations of biogas slurry were applied in peanut cultivation. The results achieved herein showed that the application of biogas slurry as a nutrient supplier in peanut cultivation would significantly affect the physical and chemical properties of soil and characteristics of the plant and the quality of peanuts. Although the heavy metal content of biogas slurry was within the permitted range, it had potential risks to human health and the environment. Principal component analysis (PCA) showed that biogas slurry was the primary source of heavy metals in soil. After the application of biogas slurry, the contents of As and Hg in the soil increased significantly, which were 11.12 and 26.67 times higher than those in the control soil. The contents of Cu, Zn, Pb, Cd, and As in peanut kernel samples under different levels of biogas slurry application were all lower than the maximum permissible limit set by the Standardization Administration of China. In contrast, the content of Hg in peanut kernels was higher than the maximum permissible limit value of 0.02 mg/kg. Peanut had a higher enrichment capacity of Cd and Zn and a higher migration capacity of Pb. The health risk assessment showed that the long-term consumption of peanuts grown with a high dosage of biogas slurry would be harmful to the health of children aged 2–6 years with a large consumption level.

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Evaluation of Brazilian potential for generating electricity through animal manure and sewage

Cited by 22 publications

References 31 publications

Chemical Methods for Hydrolyzing Dairy Manure Fiber: A Concise Review

Chemical Methods for Hydrolyzing Dairy Manure Fiber: A Concise Review

Insights to improve covered lagoon biodigesters through by-products recovery in pig farms

Comprehensive Risk Assessment of Applying Biogas Slurry in Peanut Cultivation

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