Swine diets impact manure characteristics and gas emissions: Part I protein level

Assessment of a Novel Real-Time Bio-Liquor Circulation System for Manure Management and Mitigation of Odor Potential in Swine Farming

Recently, circulating biologically treated manure in slurry pits has been used as an odor reduction technology, but few successful results have been reported, due to the lack of proper control strategies for bioreactors. This study was conducted to investigate the performance of the developed real-time controlled bio-liquor circulation system (BCS) at farm scale. The BCS was operated sequentially as per swine manure inflow (anoxic, aerobic, and settling) circulation to the slurry pit. Each operational phase was self-adjusted in real-time using a novel algorithm for detecting the control point on the oxidation reduction potential (ORP) and pH (mV)-time profiles, the nitrogen break point (NBP), and the nitrate knee point (NKP) in the aerobic and anoxic phases, respectively. The NH4-N in the slurry manure was thoroughly removed (100%) in the bioreactor, optimizing the duration of each operational phase by accurately detecting real-time control points. The newly developed real-time BCS decreased the nitrogen and organic matter in the slurry pit by >70%, and the potential ammonia and methane emissions by 75% and 95%, respectively. This study highlights that improved BCS that utilizes ORP tracking and pH (mV)-time profiles can effectively optimize BCS operation, and thereby reduce malodor and GHG emissions from swine farms.

Carbon Footprint of the Pork Product Chain and Recent Advancements in Mitigation Strategies

The carbon footprint of pork production is a pressing concern due to the industry's significant greenhouse gas emissions. It is crucial to achieve low-carbon development and carbon neutrality in pork production. Thus, this paper reviewed the recent studies about various sources of carbon emissions throughout the current pork production chain; feed production, processing, and manure management are the major sources of carbon emissions. The carbon footprint of the pork production chain varies from 0.6 to 6.75 kg CO2e·kg-1 pig live weight, and the carbon footprint of 1 kg of pork cuts is equivalent to 2.25 to 4.52 kg CO2e. A large reduction in carbon emissions could be achieved simultaneously if combining strategies of reducing transportation distances, optimizing farmland management, minimizing chemical fertilizer usage, promoting organic farming, increasing renewable energy adoption, and improving production efficiency. In summary, these mitigation strategies could effectively decrease carbon emissions by 6.5% to 50% in each sector. Therefore, a proper combination of mitigation strategies is essential to alleviate greenhouse gas emissions without sacrificing pork supply.

Deammonification Potential of Pig Slurries and Vapor Condensates from Sewage Sludge Drying-Substrate Quality and Inhibition

Deammonification is a well-established process for sludge liquor treatment and promising for wastewaters with high nitrogen loads because of its low energy demand compared to nitrification/denitrification. Two wastewaters with high NH4-N concentrations and a rising significance in Germany-pig slurry (12 samples) and condensates from sewage sludge drying (6 samples)-were studied for their deammonification potential. Furthermore, a comprehensive quality assessment is presented. Both wastewaters show a wide range in terms of CODt, CODs, TN and NH4-N, whereby condensates show a greater variability with no direct relation to dryer type or temperature. In the slurries, CODt shows a relative standard deviation of 106% (mean 21.1 g/L) and NH4-N of 33% (mean 2.29 g/L), while in condensates it reaches 148% for CODt (mean 2.0 g/L) and 122% for NH4-N (mean 0.7 g/L). No inhibition of ammonium-oxidizing-bacteria was detected in the slurries, while two out of five condensates showed an inhibition of >40%, one of >10% and two showed no inhibition at all. Since the inhibition could be avoided by mixing, deammonification can be recommended for condensate treatment. For slurry treatment, the importance of employing some form of solid-liquid-separation as a pretreatment was noted due to the associated COD.

Uncertainty in non-CO2 greenhouse gas mitigation contributes to ambiguity in global climate policy feasibility

Despite its projected crucial role in stringent, future global climate policy, non-CO2 greenhouse gas (NCGG) mitigation remains a large uncertain factor in climate research. A revision of the estimated mitigation potential has implications for the feasibility of global climate policy to reach the Paris Agreement climate goals. Here, we provide a systematic bottom-up estimate of the total uncertainty in NCGG mitigation, by developing 'optimistic', 'default' and 'pessimistic' long-term NCGG marginal abatement cost (MAC) curves, based on a comprehensive literature review of mitigation options. The global 1.5-degree climate target is found to be out of reach under pessimistic MAC assumptions, as is the 2-degree target under high emission assumptions. In a 2-degree scenario, MAC uncertainty translates into a large projected range in relative NCGG reduction (40-58%), carbon budget (±120 Gt CO2) and policy costs (±16%). Partly, the MAC uncertainty signifies a gap that could be bridged by human efforts, but largely it indicates uncertainty in technical limitations.

Control of odor emissions from livestock farms: A review

Odor emission seriously affects human and animal health, and the ecological environment. Nevertheless, a systematic summary regarding the control technology for odor emissions in livestock breeding is currently lacking. This paper summarizes odor control technology, highlighting its applicability, advantages, and limitations, which can be used to evaluate and identify the most appropriate methods in livestock production management. Odor control technologies are divided into four categories: dietary manipulation (low-crude protein diet and enzyme additives in feed), in-housing management (separation of urine from feces, adsorbents used as litter additive, and indoor environment/manure surface spraying agent), manure management (semi-permeable membrane-covered, reactor composting, slurry cover, and slurry acidification), and end-of-pipe measures for air treatment (wet scrubbing of the exhaust air from animal houses and biofiltration of the exhaust air from animal houses or composting). Findings of this paper provide a theoretical basis for the application of odor control technology in livestock farms.

Assessing Nursery-Finishing Pig Manures on Growth of Black Soldier Fly Larvae

Livestock manure is an important component of agricultural organic waste, and in recent years, with the development of research on the bioconversion of manure, BSFs have been proven to be useful in the treatment of a variety of livestock wastes. In-depth research on the composition of manure and its effect on the development of BSFL is, however, very scarce. The purpose of this study was to identify the parameters that influenced the growth of BSFL that was fed fattening pig manure. The pH, moisture, and nutrients of the fattening manures (namely, nursery, growing, and finishing pig manures) were measured. To examine the influence of manure types on larval growth, 100 larvae were inoculated in 100 g of each type of manure in triplicate. According to the findings, larvae fed finishing pig manure had the lowest dry weight (30.2 ± 6.1 mg) compared to those fed growing (58.2 ± 7.3 mg) or nursery (65.5 ± 6.2 mg) pig manure. The correlation coefficients (r) between the nutrients in the manure and the weight of the larvae were calculated. Hemicellulose had the greatest |r| value (0.9569). Further research revealed that larvae raised on hemicellulase-pretreated finishing pig manure frequently weighed 21-30% (days 2-8) more than larvae raised on control manure. In conclusion, hemicellulose was a significant component that might hinder larval growth. The results of this study could be used to improve the system before it is put into use.

Ammonia mitigation potential in an optimized crop-layer production system

Livestock and crop production are the main sources of ammonia (NH₃) emissions, which are known to degrade the air quality. Numerous studies have been conducted to explore the mitigation potential of various approaches, although few have examined the systematic NH₃ emission mitigation potential when considering both crop and livestock systems based on coherent in situ measurement results. Herein, we design an optimal system wherein coupled crop and layer production systems reveal feasible approaches for significant mitigation potential at each stage of the process. Specifically, these measures involve (i) using a low crude protein (LCP) feed, (ii) composting manure with certain additives, and (iii) substituting manure with optimal fertilization in a summer maize-winter wheat cropping system. The results show that (i) LCP feed leads to a 14 % reduction in NH₃ emissions at the housing stage, (ii) introducing additives during the composing stage reduces NH₃ emissions by 16 %-46 %, and (iii) the NH₃ reduction potential reaches 35 %-44 % at the field application stage. In the overall crop-layer system, the optimal system with the improved management strategy applied at every stage results in a 48 % and 56 % reduction in NH₃ emissions for per unit eggs and grain production, respectively, relative to a traditional production system. This study confirms that NH₃ emissions can be cut in half by implementing optimal crop-livestock systems with appropriate mitigation approaches. This is a feasible model that can be promoted and extended in various agricultural areas, which together with technological, policy, and economic support can enable significant mitigation potential for sustainable agriculture development.

Swine diets: Impact of carbohydrate sources on manure characteristics and gas emissions

Swine growers seeking to lower costs and environmental impact have turned to alternative carbohydrate feed sources. A feeding trial was conducted to determine the effect carbohydrate sources have on manure composition and gas emissions. A total of 48 gilts averaging 138 kg BW were fed diets consisting of (a) low fiber (LF) grain, or (b) high fiber (HF) aro-industrial co-product (AICP). The LF diets included corn and soybean meal (CSBM) and barley soybean meal (BSBM). The HF AICP diets were CSBM based and supplemented with one of the following materials: beet pulp; corn distillers dried grains with solubles; soybean hulls; or wheat bran. Diets were fed for 42 d with an average daily feed intake of 2.71 kg d-1. Feces and urine were collected twice daily and added to manure storage containers in which manure slurries were monitored for gas emissions and chemical properties. Manures of animals fed HF diets had significantly (P < 0.05) more excretion of solids, C, N, and organic N, but less total S compared to pigs fed the LF diets. Animals feed HF diets had significantly (P < 0.05) higher levels of ammonia, sulfide, volatile fatty acids, and phenols in manure compared to pigs fed the LF diets. Manure of animals fed HF diets had 30% (P < 0.05) lower NH3 and 17% lower hydrogen sulfide emissions; however, fiber had no impact on odor emissions. Based on the partitioning of nutrients, animals fed HF fiber diets had increased manure retention for C and N but decreased levels of N gas emissions and manure S. There were little differences in manure and gas emissions for animals fed LF diets, but the source of HF AICP diets had a significant impact on manure composition and gas emissions.

Innovative high digestibility protein feed materials reducing environmental impact through improved nitrogen-use efficiency in sustainable agriculture

Sustainable development in agriculture brings both environmental and economic benefits. Contemporary agriculture is also about increasing nutrient use efficiency, especially nitrogen, as the critical nutrient causing the most significant environmental pressure. This creates the need to produce highly digestible protein feed with high bioavailability, reducing losses of biogenic elements to feces. In this review, the latest trends and the potential for their implementation in sustainable agriculture have been compared, as well as the need to reduce the negative environmental impact of agriculture has been demonstrated. Applying local protein sources to feed animals reduces greenhouse gas emissions associated with transportation. The production of highly digestible fodder leads to a reduction in environmental pollution caused by excessive nitrogen outflows. Another approach indecreasing ammonia emissions from livestock farming is feed protein reduction and amino acid supplementation. All of the aforementioned approaches may result in beneficial long-term changes, contributing to environmental safety, animal welfare and human health.

Swine diets impact manure characteristics and gas emissions: Part II protein source

Soybean meal is the dominate protein source for swine diets in the world driven largely by economics, nutritive value, and availability; but conditions can change requiring growers to consider more economical and available protein alternatives. A feeding trial was conducted to determine the impact dietary protein source material on manure slurry chemical properties and manure gas emissions. A total of 32 gilts averaging 130 kg BW were fed either a control diet formulated with soybean meal (SB) or an alternative protein source that included corn gluten meal (CG); canola meal (CM); or poultry meal (PM), with all diets containing 176 g protein kg^-1. Diets were fed for 45 d with an average daily feed intake of 2.68 kg/d. Feces and urine were collected twice daily after each feeding and added to animal-specific manure storage containers. At the end of the study, manure slurries were monitored for gas emissions and chemical properties. Dietary protein source had a significant effect (P < 0.05) on manure pH, total solids, total C, protein N, and total S. Pigs fed the diets containing CM had significantly higher levels of sulfide, butanoic acid, and branch chain fatty acids compared to pigs fed SB diets (P < 0.05). Pigs fed CM diets had significantly lower emissions of NH₃ compared to pigs fed SB diets (P < 0.05). There were no significant differences in C or S emissions or in odorant emission as affected by source of dietary protein. Hydrogen sulfide was the most dominate odorants for all dietary treatments.

Development of a Real-Time Controlled Bio-Liquor Circulation System for Swine Farms: A Lab-Scale Study

Simple Summary

Odor emission from swine production facilities can irritate the people living in surrounding areas, although the farmers consider odor emission as a part of farming practice. Despite the governmental and institutional efforts, odor-related complaints from the neighborhood communities around the swine farms are rapidly increasing and have been identified as a key concern to sustaining progress of the swine industry globally. Bio-liquor circulation systems (BCSs) in swine farms have become popular among the farmers as an odor reduction technology in Korea. However, due to the lack of appropriate operating strategies, the odor reduction capacity of BCSs is often depleted. In this lab-scale study, a real-time control strategy based on oxidation–reduction potential (ORP) and pH (mV) time profiles was developed and applied for BCS operation. This study shows the potential effectiveness of using ORP and pH (mV) time profiles as operational parameters for the BCS to improve swine manure properties in slurry pits and thus reduce odor emission.

Abstract

In this study, an attempt was made to develop a real-time control strategy using oxidation–reduction potential (ORP) and pH (mV) time profiles for the efficient operation of bio-liquor circulation system (BCS) in swine farms and its effectiveness in reducing odor emission through improving manure properties in the slurry pit was evaluated. The lab-scale BCS used in this study comprised a bioreactor and a slurry pit. The bioreactor was operated in a sequence of inflow of swine manure → anoxic phase → aerobic phase → circulation to the slurry pit. The improvement in swine manure properties was elucidated by comparing the results of the BCS slurry pit (circulation type, CT) and conventional slurry pit (non-circulation type, NCT). The results revealed that the ORP time profile successfully detected the nitrate knee point (NKP) in the anoxic phase. However, it was less stable in detecting the nitrogen break point (NBP) in the aerobic phase. The pH (mV) time profile showed a more efficient detection of NBP. Compared to the NCT slurry pit, concentrations of ammonium nitrogen (NH₄-N) and soluble total organic carbon (STOC) and other analyzed swine manure properties were much lower in the CT slurry pit. In the aspect of odor reduction, around 98.3% of NH₃ was removed in the CT slurry pit. The real-time controlled BCS can overcome the drawbacks of fixed time-based BCS operation and therefore can be considered as a useful tool to reduce odor emission from intensive swine farming operations. However, further studies and refinement in control algorithms might be required prior to its large-scale application.