Effects of particle size on the pretreatment efficiency and subsequent biogas potential of polylactic acid.

The fragmentation of bioplastics (BPs) before pretreatment and anaerobic digestion is conducted for higher efficiency; however, based on the literature, the size reduction varies widely. In this study, initially, various combinations of thermal-alkaline pretreatments were applied at different strengths to the polylactic acid (PLA) in three groups (<0.5, 0.

Continuous production of high-concentrated ammonia broth through fermentation.

Being considered as a valuable resource and energy carrier, extensive research is going on to efficiently extract ammonia (NH) from anaerobic digestate. However, due to the well-known NH inhibition on methanogens, the total NH nitrogen (TAN) concentration is typically limited to 1-4 g N/L in digestate, making the NH extraction process energy-consumptive. Here, NH fermentation, specifically targeting augmented NH production through biological reaction, was performed in a continuous mode.

Use of reverse osmosis concentrate for mitigating greenhouse gas emissions from pig slurry.

Due to the high global warming potential (GWP) in a short time scale (GWP100 = 28 vs. GWP20 = 86), mitigating CH emissions could have an early impact on reducing current global warming effects. The manure storage tank emits a significant amount of CH, which can diminish the environmental benefit resulting from the anaerobic digestion of manure that can generate renewable energy.

Upflow anaerobic sludge blanket reactor operation under high pressure for energy-rich biogas production.

Autogenerative high-pressure digestion has an advantage of producing CH-rich biogas directly from the reactor. However, its continuous operation has rarely been reported, and has never been attempted in an upflow anaerobic sludge blanket reactor (UASB). Here, UASB was continuously operated at 10 g COD/L/d with increasing pressure from 1 to 8 bar.

Enhanced anaerobic treatment of sulfate-rich wastewater by electrical voltage application.

Treatment of sulfate-rich wastewater with high methane recovery is a major concern due to sulfide inhibition. Here, an electrical voltage (EV) aims to enhance methanogenesis and sulfidogenesis to treat sulfate-rich wastewater. Two (control and EV-applied) reactors were operated with a gradual decrease in chemical oxygen demand (COD)/SO ratios (CSR).

Electrical voltage application as a novel approach for facilitating methanogenic granulation.

Despite having high-rate methanogenic performance, up-flow anaerobic sludge blanket reactor still has challenges regarding long-start up period (3-8 months) for granulation. In this study, "electrical voltage (EV, 0.3 V) application" was attempted for facilitating granulation in the continuous operation with increased organic loading rates (0.

Environmental Injustices of Leaks from Urban Natural Gas Distribution Systems: Patterns among and within 13 U.S. Metro Areas.

Natural gas leaks in local distribution systems can develop as underground pipeline infrastructure degrades over time. These leaks lead to safety, economic, and climate change burdens on society. We develop an environmental justice analysis of natural gas leaks discovered using advanced leak detection in 13 U.

Automatic temperature rise in the manure storage tank increases methane emissions: Worth to cool down!

A significant amount of CH is emitting from livestock manure (LM) storage tank, which is being counted according to the guidelines provided by the Intergovernmental Panel on Climate Change (IPCC). Among various parameters affecting CH conversion factor (MCF) of LM, temperature is known as the most influential factor. As a degree of temperature, atmospheric temperature (T), not the manure temperature (T), is used for determining the MCF.

Electron bifurcation reactions in dark fermentation: An overview for better understanding and improvement.

Electron bifurcation (EB) is the most recently found mode of energy conservation, which involves both exergonic and endergonic electron transfer reactions to minimize energy loss. Several works have been devoted on EB reactions (EBRs) in anaerobic digestion but limited in dark fermentative hydrogen production (DF). Two main electron carriers in DF are ferredoxin (Fd) and reduced nicotinamide adenine dinucleotide (NADH), complicatedly involved in EB.

Production of high-calorific biogas from food waste by integrating two approaches: Autogenerative high-pressure and hydrogen injection.

Auto-generative high pressure digestion (AHPD) and hydrogen-injecting digestion (HID) have been introduced to directly produce high CH-content biogas from anaerobic digester. However, each approach has its own technical difficulties (pH changes), and practical issues (high cost of H) to obtain > 90% CH containing biogas, particularly, from the high-strength waste like food waste (FW). To overcome this problem, in this study, AHPD and HID were integrated, which can offset each drawback but maximize its benefit.

Use of citric acid for reducing CH and HS emissions during storage of pig slurry and increasing biogas production: Lab- and pilot-scale test, and assessment.

The use of sulfuric acid (SA) for reducing greenhouse gases (GHGs, mainly CH) emissions in manure management encounters with problems related with safety issue and increased HS emissions. In the present study, citric acid (CA) as an alternative to SA was assessed in the lab-scale experiment at various dosages (pH 5.0-7.

Combination of HSO-acidification and temperature-decrease for eco-friendly storage of pig slurry.

Owing to the economic benefit and efficiency, HSO-acidification is often applied for reducing CH emissions during storage of pig slurry (PS). However, it encounters with several problems related with safety and the concomitant HS emissions. To reduce the required amount of HSO, in this study, the storage at low temperature (20-35 °C) was applied to the mild-acidified PS (pH 6.

Enhanced Anaerobic Digestion of Long Chain Fatty Acid by Adding Magnetite and Carbon Nanotubes.

This study investigated the impact of stimulating direct interspecies electron transfer (DIET), by supplementing nano-sized magnetite (nFeO, 0.5 g Fe/g VSS) and carbon nanotubes (CNT, 1 g/L), in anaerobic digestion of oleic acid (OA) at various concentrations (0.10 - 4.

Effects of storage temperature on CH emissions from cattle manure and subsequent biogas production potential.

CH is one of the main greenhouse gases (GHGs) generated from agricultural sector, and a significant amount of it is emitted during the storage of livestock manure. To mitigate the CH emissions, strong acid addition to the manure was attempted, which is only applicable to slurry-type manure. On the other hand, lowering the storage temperature could be an effective method to reduce the CH emissions, particularly applicable to solid-type manure.

Effects of pig slurry acidification on methane emissions during storage and subsequent biogas production.

In addition to undesirable odorous gases, substantial amounts of greenhouse gases (GHG), particularly methane (CH), are generated during the storage of livestock manure. To reduce the CH emissions, first, pig slurry (PS) was stored for 40 d at 30 °C after adjusting the pH at 5.0-7.

Biohydrogen production from food waste: Current status, limitations, and future perspectives.

Among the various biological routes for H production, dark fermentation is considered the most practically applicable owing to its capability to degrade organic wastes and high H production rate. Food waste (FW) has high carbohydrate content and easily hydrolysable in nature, exhibiting higher H production potential than that of other organic wastes. In this review article, first, the current status of H production from FW by dark fermentation and the strategies applied for enhanced performance are briefly summarized.