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2022 ◽  
Vol 9 ◽  
Author(s):  
Jingyang Shi ◽  
Guangyi Zhang ◽  
Hang Zhang ◽  
Fa Qiao ◽  
Jie Fan ◽  
...  

To reveal the effects of thermal hydrolysis (TH) pretreatment (THPT) on anaerobic digestion (AD) of protein-rich substrates, discarded tofu was chosen as the object, and its batch AD tests of tofu before and after being subjected to TH at gradually increasing organic loads were carried out and the AD process characteristics were compared; furthermore, its continuous AD tests without and with THPT were also conducted and the difference of the microbial community structures was investigated. The results showed that, during AD of protein-rich tofu with increase in the organic load, inhibition from severe acidification prior to accumulation of ammonia nitrogen (AN) occurred. THPT helped overcome the acidification inhibition present in batch AD of tofu at such a high TS content of 3.6%, to obtain the maximum methane yield rate of 589.39 ml·(gVS)−1. Continuous AD of protein-rich tofu heavily depended on ammonia-tolerant hydrogenotrophic methanogens and bacteria. The continuous AD processes acclimated by HT substrates seemed to be resistant to severe organic loads, by boosting growth of ammonia-tolerant microorganisms, above all methylotrophic methanogens such as the genera RumEnM2 and methanomassiliicoccus. The process response of continuous AD of HT tofu was hysteretic, suggesting that a sufficiently long adaptation period was required for stabilizing the AD system.


2022 ◽  
Vol 11 (1) ◽  
pp. e6811121720
Author(s):  
Hellen Luisa de Castro e Silva ◽  
Regina Mambeli Barros ◽  
Ivan Felipe Silva dos Santos ◽  
Electo Eduardo Silva Lora ◽  
Marco Aurélio Kondracki de Alcântara ◽  
...  

The agro-industrial systems comprise activities which transform raw materials of agricultural, aquacultural, livestock and forestry industries from primary production stages to consumption. Pig farming stands out in national and international markets for agro-industrial processes such as slaughtering and meat processing. Although this sector positively contributes to the economies of several countries, the high flow of waste resulting from implementing integrated production systems has led to serious environmental consequences (e.g.,  polluted water bodies and Greenhouse Gases - GHGs emissions). Among the treatment methods, anaerobic digestion reduces the organic load of biomass in the absence of oxygen, generating biogas and organic fertilizer. However, there are limitations associated with high CH4 variability and low yield, resulting a minimal and slow implementation in Brazil. Some research has reported the use of mineral additives to optimize the digestion process. This study comprises a bibliographic review of pig farming systems and production models, followed by an analysis on a global scale and environmental consequences. It is also discussed the use of additive minerals which have been applied in anaerobic digestion of swine manure as well as some prospects for global advances with opportunities to mitigate GHGs and bottlenecks. Despite being a promising technology, detailed evaluations of the use of these additives and their implementation in treatment plants must still be carried out in such a way to understand the optimization of such process.


2022 ◽  
Vol 334 ◽  
pp. 08005
Author(s):  
Elisa Casula ◽  
Michele Mascia ◽  
Giorgia De Gioannis ◽  
Mirella Di Lorenzo ◽  
Marco Isipato ◽  
...  

Microbial fuel cells (MFCs) exploit the metabolic activity of electroactive microorganisms for oxidation of organic compounds and extracellular electron transfer to an external electrode. the technology is associate with very slowreaction rates, resulting in low current densities. Anodes with high specific surface should be used to increase the overall electricity generation. Carbon-based 3D materials, with high surface per unit of volume, are largely used anode materials in MFCs, although may show significant lack in efficiency due to mass transfer limitations, concentration gradients, velocity distribution and resistivity of the material. Consequently, the concomitant effect of several parameters should be assessed and quantified to design highly performing MFCs implementing 3D anode materials. In this work, miniature MFCs with 3D anodes are mathematically modelled to quantify the effect of operative parameters on performance. The model combines equations of charge conservation, mass transport phenomena, hydrodynamics, and kinetics of the involved processes under transient conditions, and provides 3D profiles with time of velocity, biofilm thickness, substrate concentration, current density and potential. The solution predicts a laminar flow, as it was expected with the low flow rates used. The concentration profiles show the consumption of substrate in the anode, with low values of local concentrations depending on organic load in the feed stream. The model also provides a versatile tool to optimise the operative conditions of the system, managing the flow arrangements to maximise either substrate removal or electricity generation.


Author(s):  
Elena Mikhailovna Evgrafova ◽  
Alexander Nickolaevich Nevalennyy ◽  
Lina Yurievna Lagutkina ◽  
Aliya Baimuratovna Akhmedzhanova ◽  
Elena Pershina

The article focuses on the problem of adopting the effective methods for combined cultivation of food products in cities, which requires the rapidly deployable and scalable aquaponic urban farms for year-round cultivating the aquaculture and crop products. Experimental work on cultivating the agricultural products in a small-sized system of combined recirculating fish farming and intensive crop production (aquaponics) has been carried out. A well-grounded idea of the qualitative and quantitative requirements for feed formulations, the possibilities of their optimization due to including the ingredients of natural origin was obtained. With combined recirculating fish farming and intensive crop production the control over the physiological state of the aquatic organisms grown on feed on their own formulation is carried out on the analysis of special biochemical parameters, which complement the general characteristics of the limits of reference values of homeostasis constants and determine the physiological status of fish. Feeding rates (% of body weight) of fish determine the amount of organic load for nutrition of plant growing objects, in particular leafy greens. In the course of research it was found out that when feeding sterlet (100 g) with the developed feed with protein content 45% the feeding rate is 4% of the body weight. The equivalent area 1 m2 with leafy greenery accounts for 40–50 g of feed with a mass of water bodies up to 5.0 kg/m3.


2021 ◽  
Vol 2 (6) ◽  
pp. 29-35
Author(s):  
M. Lenzi ◽  
M. Leopatti Persiano ◽  
M. Ciarapica

An experience in seawater microcosms was conducted to evaluate the effectiveness of the zeolite chabazite (CHA) in the mitigation of water eutrophication produced by sediments with high organic load. The experience was conducted in microcosms with addition and in the absence of effective microorganisms (EM). In the absence of EM, the ammonium abatement by CHA compared to the controls without CHA, was elevated only in the first week, while with the addition of EM, the abatement occurred for the entire experience (one month), although gradually reducing, as ammonia releases increased over time. Ammonium releases were 1.4 to 2.3 times lower in CHA microcosms compared to CHA-free controls and, among those in which CHA was present, they were lower in the presence of EM. Soluble orthophosphates also showed a reduction in microcosms with CHA, compared to the control microcosms, with a more marked results in the absence of EM, probably due to the formation of insoluble salts.


2021 ◽  
Vol 2 (1) ◽  
pp. 12-24
Author(s):  
Badrinath Vengarai Jagannathan ◽  
Steven Kitchens ◽  
Stuart Price ◽  
Melissa Morgan ◽  
Paul Priyesh Vijayakumar

Foodborne illness due to the consumption of contaminated products continues to be a serious public health issue. Bacteriophages might provide a natural and effective way to control and reduce the pathogenic bacterial population on food products. Researchers have conducted various experiments to prove their effectiveness against different pathogens and their ability to act as a natural intervention to control pathogen populations, especially in the food industry. In this study, a cocktail of bacteriophages (phages) was added to wash water in the presence of a high organic load along with commercially used sanitizers (chlorine or Sanidate 5.0) to study the efficacy of the phage–sanitizer combination in the challenge water. It was determined that in the absence of organic loads, the sanitizer by itself or the combination with phages significantly (p < 0.001) reduced the contamination by 3.00–5.00 log CFU/mL. In the presence of organic loads, the sanitizer by itself did not contribute to a significant reduction (p > 0.05) compared to the control. However, the sanitizer–phage combination led to a 3.00-log and 6.00-log reduction (p < 0.001) of the pathogen at the end of 3 and 6 h, respectively, in the presence of high organic loads. Therefore, utilizing a combination treatment (phage–sanitizer) might be one solution to reduce pathogen contamination in the food industry, especially the fresh produce industry, thus providing safe food for consumption.


Author(s):  
Itzel Romero-Soto ◽  
Celestino Garcia-Gomez ◽  
Luis Leyva-Soto ◽  
Juan Napoles-Armenta ◽  
María Concha-Guzman ◽  
...  

Abstract The application and design of treatment systems in wastewater are necessary due to antibiotics' potential toxicity and resistant genes on residual effluent. This work evaluated a coupled bio-electrochemical system to reduce chloramphenicol (CAP) and chemical oxygen demand (COD) on swine wastewater (SWW). SWW characterization found CAP of &lt;10 μg/L and 17,434 mg/L of COD. The coupled system consisted of preliminary use of an Up-flow Anaerobic Sludge Blanket Reactor (UASB) followed by electrooxidation (EO). UASB reactor (primary stage) was operated for three months at an organic load of 8.76 kg of COD/m3d and 50 mg CAP/L as initial concentration. In EO, we carried out a 22 (time operation and intensity) factorial design with a central composite design; we tried two Ti cathodes and one anode of Ti/PbO2. Optimal conditions obtained in the EO process were 240 min of operation time and 1.51 A of current intensity. It was possible to eliminate 44% of COD and 64.2% of CAP in the preliminary stage. On bio-electrochemical, a total COD and CAP removal were 82.35% and &gt;99.99%, respectively. This coupled system can be applied to eliminate antibiotics and other organic pollutants in agricultural, industrial, municipal, and other wastewaters.


Author(s):  
DARWIN ◽  
◽  
MARDHOTILLAH ◽  
ATMADIAN PRATAMA ◽  
◽  
...  

Anaerobic co-digestion of oil palm frond waste with cow-manure was evaluated. The study aimed to evaluate a stepwise organic load with an increase solid concentration to the on-going anaerobic digestion of cow manure. The anaerobic digestion process was operated in continuous mode under the mesophilic condition. Results showed that the maximum methane productivity of 1700 ml CH4∙day-1 was obtained when the anaerobic co-digestion of OPFW and cow manure was loaded with the substrate concentration between 4 and 8% TS. The pH culture dropped dramatically from 6.9 to 6.3 when substrate concentration was increased from 10 to 12% TS. The acidic pH had restricted the conversion of organic materials in which the COD removal was less than 25% removal. This study is exceedingly notable for the industrial development of waste management processes, which handle and treat tons of organic wastes daily.


2021 ◽  
Vol 10 (16) ◽  
pp. e550101624044
Author(s):  
Rogério Ferreira da Silva ◽  
Gilson Lima da Silva ◽  
Victória Fernanda Alves Milanez ◽  
Gustavo José de Araújo Aguiar ◽  
Marcelo Fabrício Araújo ◽  
...  

Textile industries activities can positively affect a city’s economy. However, those industries require a great deal of water and sheds high organic load into water bodies, causing a considerate environmental impact. As potential pollutant substances, the dye’s presence in textile effluents are recalcitrant and can change the chemical and physical properties. It also resists conventional treatments. The treatment based on advanced oxidation processes presents to be efficient on dye’s degradation, but it may generate secondary toxic compounds, therefore is necessary to use techniques to evaluate its toxicity after the treatment. This study evaluated a laundry effluent, both before and after the treatment using the photo - Fenton processes. Applying liquid chromatography, results have shown that the dye's degradation was higher than 90% and a COD decrease to 73%.


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