Tuesday, October 31, 2017

What is a Biogas Plant?

The question of "What is a Biogas Plant?" is becoming a popular question as biogas plants, also known as anaerobic digestion plants, become more common, and people hear about them talked about through various routes.

We set about answering the question by making a video in which we go further to describe what goes in inside a biogas facility, stage by stage.

The video which follows is the result of that exercise in providing information, and the video also explains upgrading biogas to become biomethane, because this is becoming such a common feature of many UK biogas plants:

In case for any reason you are unable to watch the video, we have copied the text from the video below:

What is a Biogas Plant? (Transcript)

Biogas is mostly methane gas, and when methane burns it produces a clean heat source, without harmful by-products. It is also a "renewable" energy, and because it is renewable it is also said to be "green" and eco-friendly.

The best way to understand what a biogas plant is, is to know what happens inside a biogas plant, which we will now explain.

1 - Organic material arrives at the biogas plant.

These are also known as anaerobic digestion facilities. The organic material delivered may include animal manure, food waste, agricultural residues, or wastewater solids (sludge).

The organic materials are the "input", or "feed" for the biogas plant. Each individual biogas plant is tailor-made for the feed materials which it will accept. The accepted materials may be from just one source or a combination of several types of organic food source.

2 - Organic material is broken down in a "digester".

The digester is a big tank or multiple tanks for wet digestion, (where the biomass is mixed in water).

Or, the digester may be a long tube, for plug-flow digestion.

And, sometimes (for a dry digester which operates on biomass solids), the digester reactor vessel is configured like a tunnel.

A tunnel type dry digester may be rounded, with large paddles to move the feedstock through the digester.

Or, the digester may have a flat floor for batch-by-batch production, and be large enough for feedstock loading and unloading vehicles to work in.

The digester is always airtight, and is usually equipped with mixing and heating equipment.
Naturally occurring microorganisms grow in the zero-oxygen environment.

They use the organic matter as their food, and break down (digest) the organic matter.

At most AD plants the digester is continuously fed with organic materials (the feedstock) and biogas, and the remaining liquid and solids, are also simultaneously discharged.

3 - Raw biogas is produced.

The biogas flows out of the digester continually and is made of mostly methane. It also contains carbon dioxide, water vapour, and small amounts of what are known as, "trace" compounds.

"Natural gas" which is made from fossil fuels is methane like biogas, the difference is that natural gas contains none of the impurities we just mentioned, two slides ago.

The most damaging impurities, if not removed from the biogas, are usually hydrogen sulphide, and siloxanes.

Biogas can replace "natural gas", but first it must be processed to as far as possible, remove everything but the methane.

The degree of processing which takes place in the anaerobic digestion plant varies according to the use intended for the upgraded biogas.

Upgraded biogas of the highest quality is called "biomethane" or "renewable natural gas".

4 - After digestion in the Anaerobic Digestion Plant (Biogas Facility), which can take anything from 5 days to 60 days, the biogas is used in one of many ways.

Biogas may be used to: Produce heat, electricity, vehicle fuel. Or, it may be used for injection in the gas grid (natural gas pipelines), after it has been upgraded to become "biomethane".

5 - However, the biogas accounts for only a small proportion of what is left, after digestion. 

The digester residue is known as "digestate" comprising solid fibres and a liquid.

The solids and liquids can be used to provide marketable products, such as fertiliser, compost, soil amendments or animal bedding.

These are called "co-products", and can be sold for a profit.

We hope that you now have a clear understanding of what a biogas plant does.
If you would like to read more, we suggest the following sources.

For the original American Biogas Council article upon which this was based, go to https://anaerobic-digestion.com/abiogasc

For our detailed article, visit our A.D. website at: https://anaerobic-digestion.com/anaerobic-digestion-basics

Videos like this one, are available to order. Get a quote from us now... via: https://anaerobic-digestion.com/advertising


Monday, October 16, 2017

How to Feed a Digester Weltec MultiMix - Better Biogas Yield and Stability

How to Feed a Digester for High Biogas Output - Weltec MULTIMix 

Visit: http://blog.anaerobic-digestion.com/weltec-biopower-extends-ad-plant-france/
How to Feed a Digester for High Biogas Output The Weltec MULTIMix Way.

Avoid problems with inconsistent throughout quality, and avoid downtime when feeding a digester with, grass silage, whole-plant silage, and manure for biogas production.

With the MULTIMix digester feed delivery system, WELTEC BIOPOWER offers a unique solution which removes foreign materials, BEFORE being conveyed to the feed pump.

The system also shreds the substrate to size and consistency which is optimised, for rapid uptake by the biogas bacteria.

The MULTIMix system thus ensures the technical and economic stability of biogas plants, by preventing failures, and thus ensuring an uninterrupted process of digestion of the substrates used.

Advantages of Installing a Weltec MULTIMix:

1, Processes fibrous, sticky and soft substrates (up to a high dry weight percentage).
2, Provides bacteria-oriented substrate shredding for immediate biogas production.
3, Ensures an optimum loading of the digester with a homogeneous, macerated bio-suspension.
4, Minimises the risk of floating and sediment layers.
5, Improves overall anaerobic digestion plant energy efficiency, through the reduction of agitation energy needed, and significantly increases the pump feed pump's typical service life.
which substantially reduces wear and tear.

Two quick MULTIMix tips, for biogas plant operators, follow:

Tip 1, Several digesters can be fed with only one MULTIMix.
Tip 2, A MULTIMix unit can easily be retrofitted to your biogas plant.

Video based on the Weltec MULTIMix web page at www.weltec-biopower.com

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CLICK HERE: http://blog.anaerobic-digestion.com/weltec-biopower-extends-ad-plant-france/

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More Information about Feed Digester:

Feedstocks | Anaerobic Digestion
www.biogas-info.co.uk/about/feedstocks/
The material that is used in anaerobic digestion is called feedstock. What goes into a digester determines what comes out, so careful choice of feedstocks is ...

Digester Feed Products - Vogelsang USA
www.vogelsangusa.com/products/digester-feed-products/?L=1
Biogas technology needs to be secure and efficient at all times to enable cost-effective plant operation. Digester feeding plays a key role here. Wet feeding is the ...

[PDF]“Design & Analysis of an Anaerobic Digester to Feed a Biogas Fuelled ...
research.ncl.ac.uk/pro-tem/components/pdfs/material.../Butcher_Design&analysis.pdf
19 Aug 2010 - “Design & Analysis of an Anaerobic Digester to Feed a. Biogas Fuelled Boiler for a Medium Sized. Industrial Enterprise”. Matthew Butcher.

Biogas - Digester Feed Material
www.biogassa.co.za/index.php/biogassa-blog/112-digester-feed
Anaerobic digestion - Wikipedia
https://en.wikipedia.org/wiki/Anaerobic_digestion
Anaerobic digestion is a collection of processes by which microorganisms break down ..... The residence time in a digester varies with the amount and type of feed material, and with the configuration of the digestion system. In a typical two-stage ...

Silage - Wikipedia
https://en.wikipedia.org/wiki/Silage
Silage is fermented, high-moisture stored fodder which can be fed to cattle, sheep and other such ruminants (cud-chewing animals) or used as a biofuel feedstock for anaerobic digesters. .... The advantages of silage as animal feed are several: During fermentation, the silage bacteria act on the cellulose and carbohydrates in ...

Digestate - Wikipedia
https://en.wikipedia.org/wiki/Digestate
Digestate is the material remaining after the anaerobic digestion of a biodegradable feedstock. Anaerobic digestion produces two main products: digestate and ...

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Wednesday, October 11, 2017

Remarkable Uses for Sewage Sludge Including Producing Biogas

What could possibly be the use for all that mucky filthy smelly sewage sludge? 
NEVERTHELESS, We found some remarkable uses for Sewage Sludge, Including producing biogas. 

Sewage sludge, which is the by-product of the treatment of our foul sewage in wastewater treatment works on first sight would seem to be a useless material, but is it? We set out to find out, and the result is this article. Scroll down to see that.

1. Hygienize It and Spread It on Land: 

If spread on land it will raise soil-available phosphorous says Wikipedia (see below). That's a good outcome for the growth of crops, but raising soil salinity is not so good, so we guess we had better keep looking. 
Use of sewage sludge has shown an increase in the level of soil-available phosphorus and soil salinity, also heavy metals build-up. The findings of a 20-year field study of air, land, confirmed this ... via Sewage sludge - Wikipedia

2. Use it as Alternative Fuel source in the Cement Industry: 

An attractive disposal method for sewage sludge is to use it as an alternative fuel source in the cement industry. The resultant ash is incorporated in the cement matrix. via Use of Sewage Sludge in Cement Industry - BioEnergy Consult

4. Make Coal: 

Carbonscape out of New Zealand microwaves and compresses organic matter – wood chips, corn stalks and even sewage – into eco-coal. It burns like regular coal, but the carbon doesn't come deep from the ground. Renewable Fuel Technology, meanwhile, has devised a modified version of the Fischer-Tropsch process to convert organic matter into coal. Organic matter gets converted to syngas first.

5. Produce Biogas and Purify that Into Pipeline-Grade Methane: 

BioEnergy Solutions builds, maintains and operates the anaerobic manure digesters that convert manure into methane. The process isn't entirely green – carbon dioxide in the gas from the manure has to be burned off before the methane can be sent down a pipeline – but it does eliminate many of the hazards associated with manure. Revenue can also be generated through carbon credits and selling the solids as cow beds or fodder for, maybe someday, organic flooring or building materials. via 11 Great Things to Do With Sewage | Greentech Media

6. Make a Sludge Compost Using USDA's Method:  

When sewage sludge and woodchips are mixed and composted, as by the Beltsville aerated pile method (Willson et al., 1980),!/ a stabilized product results from the action of aerobic thermophilic microorganisms, which utilize a part of the organic material for their growth and activity. During this decomposition, the composting biomass heats to temperatures in the pasteurization range of 55*^ to 70^C, with the resulting destruction of enteric pathogenic microorganisms. The end result is humus like material useful as a soil conditioner and a source of plant nutrients. It is essentially free of human enteric pathogens and offensive odors. via Sludge Compost as - USDA 

7. Extract Gold from Sewage Sludge! 

In some sites, "concentrations of gold in sewage sludge are sufficiently high for recovery to be ... The USGS has explored ways to remove potentially dangerous metals from treated sewage that is used as fertilizer and also pursued the possibility of ... via There's Gold In Them Thar Sewage Pipes, Swiss Researchers Say

8. Use Sewage Treatment Plants Sludge to Ensure Greenery at 4 Parks

Secondary treated sewage will be further treated using chlorine. The settled sludge is sent for recirculation to the equalisation tank. The dry sludge coming out of the system can be used as manure. According to officials, this will be rolled out to other ... via Sewage treatment plants to ensure greenery at 4 parks

9. Extract energy from Sewage Sludge:



A water company says new techniques can help it extract 90% of calorific value from sewage sludge.

Thames Water is planning to greatly increase the amount of energy it can extract from sewage sludge.

The water company can currently only extract half of the calorific value – the energy contained in raw sewage – from the sludge it treats by using anaerobic digestion (AD) to turn it into gas.

However, external affairs and sustainability director Richard Aylard told the London Infrastructure Summit yesterday (October 2017) that the company was developing new AD methods that could nearly double the amount of energy it can use.

“That will get us to 90% and also massively reduce the amount of residue that has to go out to farms,” Aylard told delegates. via Thames Water to increase energy extraction from sewage

10. New Technology Turns Poo Sewage Sludge to Petroleum-Like Biocrude Oil
A team of scientists from the Pacific Northwest National Laboratory (PNNL) at the US Department of Energy has found a way to reuse sewage sludge into biocrude oil, turning human waste into reusable fuel.

According to the study published by the PNNL, the researchers has devised a simple technology called hydrothermal processing (HTP). 

During HTP, sewage sludge is pressurized to about 3,000 pounds per square inch and then put into a reactor (a pressurized tube that's extremely hot at 660 degrees Fahrenheit). 

The heat in the reactor enables the cells in the sludge to break down, forming tow by-products: biocrude oil and "an aqueous liquid phase" that can be transformed into other kinds of chemical products.

"HTP converts organic material into biocrude oil, natural gas, or both, with potentially more than 99% conversion of organics. HTP uses the same processes which form fossil fuels, (heat, pressure, time, and water) but amplifies these conditions so the conversion occurs in a much shorter timeframe. 

This technology is specifically designed for wet feed stocks. The byproduct is a clear, sterile water," the Water Environment & Reuse Foundation (WERF) told Treehugger.

We hope you agree that there are some truly remarkable uses for sewage sludge!
See also www.anaerobic-digestion.com/anaerobic-digestion-basics/anaerobic-sludge-digestion