Effectiveness Of Anaerobic Digestion Research Articles

Integrated omics analysis on the bacterial community in the anaerobic digestion of chicken manure materials in biogas production farm

The overall effectiveness of anaerobic digestion is affected by the initial three phases as a result of substrates created for the methanogens to take in. In this study, the bacterial composition of the various chambers in the anaerobic digestion of chicken manure was investigated. Diversity of the microbial community for chicken manure was relatively simpler, consisting mainly of Lactobacillus, compared to the main digestion chambers with a more complex community. Chicken manure only has hydrolysis phase occurring, while the main digesters have the first three phases of anaerobic digestion concurrently occurring. A comparison of the metagenomics versus metaproteomics analysis revealed that the main difference was in the percentage of unknown microorganisms. The quantity of volatile fatty acids detected in each respective chamber suggested the effectiveness of the microorganisms in assimilating the metabolites. Successful integration of these study modes would present a better understanding on anaerobic digestion of complex systems.

Aquatic Macrophyte Biomass Periodically Harvested Form Shipping Routes and Drainage Systems in a Selected Region of Poland as a Substrate for Biogas Production

One of the identified obstacles to the development of biogas plants is the limited sources of organic substrates. Hydrophytes varying in morphology, chemical composition, and origin proved to be viable alternatives. This study’s aim was to determine the feasibility of deploying biomass from the cleansing of water reservoirs for anaerobic digestion. A mass and energy balance was estimated for Warmia–Mazury Province (Poland), the so-called Thousand Lake District. The effectiveness of anaerobic digestion was determined in anaerobic batch respirometric reactors. The biomass of hydrophytes harvested from this area approximated 38,070 Mg FM/year. The biogas yield from emergent plants approximated 350 m3/MgVS, and the average CH4 content of biogas reached 55%, whereas the respective values obtained from submerged biomass reached 270 m3/MgVS and 58% CH4. The total CH4 volume achievable from the facility fed with waste biomass of this type allows producing ca. 1,654,560 m3CH4/year, which enables reaching 866 kW theoretical thermal power and 636 kWe net electrical power with the facility. The contribution of biomass from mowing in this energy effect was about 84%, whereas that of the submerged vegetation obtained by hacking the bottom was 16%.

Shock-adaptation in a three-stage anaerobic reactor treating tofu whey wastewater

Anaerobic digestion is often used to treat wastewater with high organic content. The effectiveness of anaerobic digestion is determined by organic loading rate and hydraulic retention time, as well as influenced by temperature, pH, and wastewater composition. The multi-stage reactor system is stable towards sudden changes in the influent and fluctuations in hydraulic and organic loadings. The objective of the study was to investigate the adaptability and stability of the three-stage anaerobic reactor after a hydraulic shock loading. This study used tofu whey wastewater due to its enormous generated volume, varying COD concentration, and the low pH. A three-stage anaerobic packed-bed reactor system that had operated for 26 days at a total hydraulic retention time of 3.75 days or 1.25 day per reactor (0.33 l-wastewater per hour) was used in the experiment. The reactor was filled with wastewater at 4 l/h, twelve times the usual flow rate, for one hour. During this period, the changes in pH, COD concentration, and biogas production were monitored. Compared with the performance before the shock loading, COD and pH did not show changes after the 24-hour observation period, except for the pH in the second stage. In addition, biogas and methane production in the second stage was lower than production before the shock loading, even though the total production remained constant. This suggests that the second stage acted as the buffering reactor during the shock loading.

Effectiveness of ecotechnologies in agriculture for the recovery and reuse of carbon and nutrients in the Baltic and boreo-temperate regions: a systematic map

BackgroundAgriculture is the main sector responsible for nutrient emissions in the Baltic Sea Region and there is a growing pressure to identify cost-effective solutions towards reducing nitrogen and phosphorus loads originating from farming activities. Recycling resources from agricultural waste is central to the idea of a circular economy, and has the potential to address the most urgent problems related to nutrients use in the food chain, such as depletion of natural phosphorus reserves, water pollution and waste management. This systematic map examined what evidence exists relating to the effectiveness of ecotechnologies in agriculture for the recovery and reuse of carbon and/or nutrients (nitrogen and phosphorus) in the Baltic Sea region and other comparable boreo-temperate systems.MethodsWe searched for both academic and grey literature. English language searches were performed in 5 bibliographic databases and search platforms, and Google Scholar. Searches in 36 specialist websites were performed in English, Finnish, Polish and Swedish. The searches were restricted to the period 2013 to 2017. Eligibility screening was conducted at two levels: title and abstract (screened concurrently for efficiency) and full text. Meta-data was extracted from eligible studies including bibliographic details, study location, ecotechnology name and description, type of outcome (i.e. recovered or reused carbon and/or nutrients), type of ecotechnology in terms of recovery source, and type of reuse (in terms of the end-product). Findings are presented here narratively and in a searchable database, and are also visualised in a web-based evidence atlas (an interactive geographical information system). In addition, knowledge gaps and clusters have been identified in the evidence base and described in detail.ResultsWe found 173 articles studying the effectiveness of 177 ecotechnologies. The majority of eligible articles were in English, originated from bibliographic databases and were published in 2016. Most studies with reported locations, and given our boreo-temperate scope, were conducted in Europe and North America. The three most prevalent ecotechnologies in the evidence base (collectively 40.7%) were; soil amendments, anaerobic digestion and (vermi)composting. Manure was the principal waste source used for recovery of nutrients or carbon, making up 55.4% of the all studies in evidence base, followed by a combination of manure and crop residues (22%). There were 51 studies with 14 ecotechnologies that reported on recovery of carbon and nutrients together, predominantly via (vermi)composting and anaerobic digestion. Only 27 studies focused on reuse of recovered nutrients and carbon through soil amendments.ConclusionsThis systematic map report provides an evidence base that can be useful for researchers and decision-makers in policy and practice working on transformation from linear to circular economy in the agricultural waste sector. Three potential topics for future systematic reviews are: (1) effectiveness of products recovered from different types of agricultural wastes as soil amendments or fertilizers; (2) effectiveness of anaerobic digestion as an ecotechnology used for recovery of nutrients and carbon; (3) effectiveness of composting and/or vermicomposting as ecotechnologies used for recovery of nutrients and carbon.

Influence of a light source on microalgae growth and subsequent anaerobic digestion of harvested biomass

The aim of the study was to determine the influence of the light source on the taxonomic structure and chemical composition of the harvested biomass, and on the fermentative biogas/methane production. Cultivation of a mixed microalgae culture was carried out in closed vertical photobioreactors equipped with different light sources. The effectiveness of anaerobic digestion was analysed by respirometric measurements. The harvested microalgae biomass was characterized by various taxonomic structures and varied chemical composition depending on the light source used during cultivation stage. In variants where warm white LED lighting and red light were used, species from the Cyanoprokaryota division predominated, characterized by a high concentration of organic compounds and nitrogen in the biomass. TOC values amounted to almost 430 mg/g TS. In the remaining variants, Chlorophyta predominated, and TOC values were in the range of 388.0–411.3 mg/g TS. A significantly higher biogas/methane production (p = 0.05) was found in variants in which biomass with Cyanoprokaryota predominating was tested. The biogas yield was in the range of 383.2 L/kg VS to 400.8 L/kg VS, and the methane content was close to 55%. A lower effectiveness of biogas and methane formation were observed in variants with Chlorophyta as a predominating taxonomic group.

The effectiveness of anaerobic digestion in removing estrogens and nonylphenol ethoxylates

The fate and behaviour of two groups of endocrine disrupting chemicals, steroid estrogens and nonylphenol ethoxylates, have been evaluated during the anaerobic digestion of primary and mixed sewage sludge under mesophilic and thermophilic conditions. Digestion occurred over six retention times, in laboratory scale reactors, treating sludges collected from a sewage treatment works in the United Kingdom. It has been established that sludge concentrations of both groups of compounds demonstrated temporal variations and that concentrations in mixed sludge were influenced by the presence of waste activated sludge as a result of transformations during aerobic treatment. The biodegradation of total steroid estrogens was >50% during primary sludge digestion with lower removals observed for mixed sludge, which reflected bulk organic solids removal efficiencies. The removal of nonylphenol ethoxylates was greater in mixed sludge digestion (>58%) compared with primary sludge digestion and did not reflect bulk organic removal efficiencies. It is apparent that anaerobic digestion reduces the concentrations of these compounds, and would therefore be expected to confer a degree of protection against exposure and transfer of both groups of compounds to the receiving/re-use environment.

INFLUENCE OF ANAEROBIC DIGESTION ON DAIRY MANURE PHOSPHORUS EXTRACTABILITY

On-farm anaerobic treatment is used for solids, odor and pathogen removal, and energy recovery. Not much information is available on the effect of this treatment method on phosphorus (P) dynamics. The objective of this study was to investigate the effect of different inoculum-to-substrate ratios (ISR) on P extractability from anaerobically digested dairy manure. Dairy manure (substrate) and anaerobically digested dairy manure (inoculum) were collected from a full-scale on-farm anaerobic digester. High ISR (HIS, with ISR = 2.0) and low ISR (LIS, with ISR = 0.3) samples were prepared on a volatile solids (VS) basis. These samples were subjected to mesophilic (35°C) anaerobic digestion in batch reactors without mixing for 120 d. Specific methane yield, TS, and VS removal were higher in the LIS system compared to the HIS system. Serial and repeated extraction methods were used to characterize P extractability. De-ionized (DI) water and MgCl2 were used as extractants in the serial extraction method with extractant-to-manure ratios (EMR) ranging from 3 to 127. For repeated extraction, manure was extracted six times with DI water (EMR = 3). While anaerobic treatment decreased water-extractable P (WEP) in LIS extracts at EMR values of 3 and 7 by 28% and 24%, respectively, a significant increase (40%) in WEP occurred at an EMR of 3 at HIS. Water-extractable P in all other serial extracts of treated manure was higher than that in extracts of untreated manure regardless of ISR and EMR. Extractability of P increased sharply up to the third extraction step, after which it leveled off. The effectiveness of anaerobic digestion at LIS to reduce P extractability was also observed up to the second extraction step. In contrast, the digested manure always produced higher WEP levels for the HIS system. Our results indicate that, depending on the ISR used, anaerobic digestion of dairy manure can increase or decrease manure P extractability and, hence, its availability in runoff. However, it appears that this impact could be more pronounced under conditions where low runoff volumes are generated and for the first few precipitation events after land application of manure.