Monitoring of Trace Elements on the Anaerobic Digestion of Saline Sewage

Rice straw is an agricultural residue produced in abundant quantities. Open burning and plowing back the straw to the fields are common practices for its disposal. In-situ incorporation and burning cause emissions of greenhouse gas and particulate matter. Additionally, the energy potential of rice straw is lost. Anaerobic digestion is a technology that can be potentially used to utilize the surplus rice straw, provide renewable energy, circulate nutrients available in the digestate, and reduce greenhouse gas emissions from rice paddies. An innovative temperature phased anaerobic digestion technology was developed and carried out in a continuous circulating mode of mesophilic and hyperthermophilic conditions in a loop digester (F1). The performance of the newly developed digester was compared with the reference digester (F2) working at mesophilic conditions. Co-digestion of rice straw was carried out with cow manure to optimize the carbon to nitrogen ratio and to provide the essential trace elements required by microorganisms in the biochemistry of methane formation. F1 produced a higher specific methane yield (189 ± 37 L/kg volatile solids) from rice straw compared to F2 (148 ± 36 L/kg volatile solids). Anaerobic digestion efficiency was about 90 ± 20% in F1 and 70 ± 20% in F2. Mass fractions of Fe, Ni, Co, Mo, Cu, and Zn were analyzed over time. The mass fractions of Co, Mo, Cu, and Zn were stable in both digesters. While mass fractions of Fe and Ni were reduced at the end of the digestion period. However, no direct relationship between specific methane yield and reduced mass fraction of Fe and Ni was found. Co-digestion of rice straw with cow manure seems to be a good approach to provide trace elements except for Se.

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Enhancing anaerobic digestion of dairy and swine wastewater by adding trace elements: evaluation in batch and continuous experiments

Water Science & Technology ◽

10.2166/wst.2019.420 ◽

2019 ◽

Vol 80 (9) ◽

pp. 1662-1672 ◽

Cited By ~ 3

Author(s):

Jing Wang ◽

Maria Westerholm ◽

Wei Qiao ◽

Ahmed Mahdy ◽

Simon M. Wandera ◽

...

Keyword(s):

Trace Elements ◽

Anaerobic Digestion ◽

Critical Role ◽

16S Rrna Gene Sequencing ◽

Swine Wastewater ◽

Rrna Gene ◽

Continuous Systems ◽

Batch Tests ◽

Rrna Gene Sequencing ◽

Low Dosage

Abstract Trace elements play a critical role for microbial activity in anaerobic digestion (AD) but their effects were probably overestimated in batch tests and should be comparably evaluated in continuous systems. In this study, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+ were added in different concentrations to manure wastewater, and the effects were compared in both batch and continuous systems. The results were used to demonstrate suitable trace element compositions for AD of dairy and swine wastewater, and to compare the outcomes from batch and continuous systems. Fe2+ and Zn2+ were identified as being the most efficient stimulant of dairy and swine wastewater respectively. The addition of 5 mg/L Fe2+ and 0.4 mg/L Zn2+ increased the batch specific methane yield by 62% and 126% for dairy and swine wastewater, respectively. Nevertheless, a lower increment of 2% and 21%, for dairy and swine wastewater was obtained in the 120-day continuously-fed experiments. The 16S rRNA gene sequencing results indicated a relationship between the methanogens population, specific methanogenic activities, propionate, and dissolved hydrogen. Conclusively, the addition of a low dosage of Fe2+ and Zn2+ is a feasible strategy to enhance the methanogenic metabolism of the AD of dairy and swine wastewater respectively.

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A review on strategies to optimize metabolic stages of anaerobic digestion of municipal solid wastes towards enhanced resources recovery

Sustainable Environment Research ◽

10.1186/s42834-019-0037-0 ◽

2019 ◽

Vol 29 (1) ◽

Cited By ~ 4

Author(s):

Edwin N. Richard ◽

Askwar Hilonga ◽

Revocatus L. Machunda ◽

Karoli N. Njau

Keyword(s):

Fatty Acids ◽

Trace Elements ◽

Activated Carbon ◽

Anaerobic Digestion ◽

Volatile Fatty Acids ◽

Solid Wastes ◽

Municipal Solid Wastes ◽

Ammonia Inhibition ◽

Moisture Contents ◽

Pre Treatment

AbstractRecently, there are increased efforts by municipals and researchers to investigate the potential of utilizing municipal solid wastes (MSW) for resources recovery. In many parts of developing countries, MSW is mostly collected for disposal with little emphasis on resources recovery. However, the MSW has high organic and moisture contents, and are suitable substrates for anaerobic digestion (AD) process to recover biogas for energy and digestate which can be used as fertilizers or for soil amendments. Resources recovery from the AD process consists of four metabolic stages; hydrolysis, acidogenesis, acetogenesis, and methanogenesis. These metabolic stages can be affected by several factors such as the nature of substrates, accumulation of volatile fatty acids, and ammonia inhibition. In this review, different optimization strategies towards resources recoveries such as pre-treatment, co-digestion, trace elements supplementation, optimization of key parameters and the use of granular activated carbon are discussed. The review reveals that the currently employed optimization strategies fall short in several ways and proposes the need for improvements.

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Study on the biogas potential of anaerobic digestion of coffee husks wastes in Ethiopia

Waste Management & Research ◽

10.1177/0734242x20939619 ◽

2020 ◽

pp. 0734242X2093961 ◽

Cited By ~ 1

Author(s):

Ning Du ◽

Meng Li ◽

Qian Zhang ◽

Mihret Dananto Ulsido ◽

Ruyi Xu ◽

...

Keyword(s):

Trace Elements ◽

Organic Matter ◽

Anaerobic Digestion ◽

Volatile Fatty Acids ◽

Biogas Production ◽

Dual Purpose ◽

Effective Utilization ◽

Leading Role ◽

Initial Ph ◽

Waste Reclamation

The poorly controlled discharge of coffee husks in Ethiopia causes severe environmental pollution and is a waste of resources. The volatile solid and carbon content in coffee husks waste indicates that it is rich in organic matter and has huge potential to produce biogas. This study investigated the feasibility of coffee husks to produce biomass through anaerobic digestion, based on temperature, initial pH, inoculum/substrate (I/S) ratio and carbon/nitrogen (C/N) ratio. The study demonstrated that the maximum production of biogas and methane reached 3359.6 ml and 2127.30 ml, respectively, under the conditions of mesophilic temperature (35±1°C), an initial pH of 7, an I/S ratio of 0.75 and a C/N ratio of 30. Based on this result, the effects of trace elements (Fe2+, Ni2+, Co2+) on biogas production and methane content were also explored. Compared with the group with no addition of trace elements, the experiment adding trace elements had significant enhancement effects on the production of biogas and methane, in which Fe2+ played a leading role ( p<0.05). Fe2+ promoted the hydrolysis and acidification of coffee husks, resulting in the production of a series of intermediates such as volatile fatty acids and the other kinds of dissolved organic matter. Furthermore, the cooperation of Ni2+, Co2+ and Fe2+ enhanced the activity of the enzyme system in methanogens, promoting methane production. The results in this paper show that coffee husks have clear biogas potential through anaerobic digestion, and its effective utilization could fulfill the dual purpose of solid waste reclamation and local environmental protection in Ethiopia.

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The valuation of malnutrition in the mono-digestion of maize silage by anaerobic batch tests

Water Science & Technology ◽

10.2166/wst.2008.491 ◽

2008 ◽

Vol 58 (7) ◽

pp. 1453-1459 ◽

Cited By ~ 59

Author(s):

L. Hinken ◽

I. Urban ◽

E. Haun ◽

I. Urban ◽

D. Weichgrebe ◽

...

Keyword(s):

Trace Elements ◽

Anaerobic Digestion ◽

Trace Element ◽

Biogas Production ◽

Renewable Energy Sources ◽

Anaerobic Bacteria ◽

Trace Element Content ◽

Energy Crops ◽

Maize Silage ◽

Batch Tests

Anaerobic digestion is a technology which is used to produce methane from organic solids and energy crops. Especially in recent years, the fermentation of energy crops has become more and more important because of increasing costs for energy and special benefits for renewable energy sources in Germany. Anaerobic bacteria require macro and micro nutrients to grow. Absence of these elements can inhibit the anaerobic process significantly. In particular mono-substrates like maize or certain industrial wastewater often cannot provide all required nutrients. For this reason this research investigates the influence of substrate and trace elements on anaerobic digestion in detail. Different agricultural anaerobic biomasses are analysed with special regard to their trace element content. Based on these results, the influence of three trace elements (iron, cobalt, and nickel) on anaerobic digestion was studied in anaerobic batch tests at different sludge loading rates and for different substrates (maize and acetate). Biogas production was found to be 35% for maize silage and up to 70% higher for acetate with trace element dosage than in the reference reactor.

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