Dear Max,

thanks a lot for this interesting information. I already heard about Ostara, as they implemented a nutrient recovery plant with Thames water London in 2013, based on the struvit precipitation process. And I would be curious to hear about your pilot plant results.

For us, the P-recycling is not the only topic. Since 2006, it is forbidden in Switzerland to bring sewage sludge on agricultural fields and it has to be treated thermically. Also, it will be a must to recovery a certain percentage of phosphorus. Therefore we were looking for a process that can combine both effects.

For the wastewater treatment plant that I mentioned, it is additionally of interest to gain thermal energy for a district heating system.

So the reasons why we are looking for a suitable pyrolyses process are
- gaining (thermal) energy
- thermical treatment of sludge and volume reduction
- recovery of phosphourus
- P-recovery from sludge seems to have a better efficiency than from the liquid phase

I would be glad if the discussion is going on.
Cheers,
Sabine

Hi Sabine,

just saw the messages and got interested in your application.
Was wondering how this particular wwtp is set up and if it might be possible to extract the phosphorus in an earlier process stage. Then you won't have to deal with heavy metals etc..

I am currently working for the eThekwini Municipality (EWS) in Durban, South Africa. We have been looking for phosphorus recovery technologies (instead of just removing it) to reach low effluent concentrations and were in contact with different suppliers. But the process would be installed after the sludge thickening step, in our case a Huber belt press, to treat the filtrate stream which goes back to head of works.
The proposed process is a precipitation process which recovers the phosphorus as struvite by adding magnesium. Struvite is a phosphorus rich fertiliser which could be used directly or by fertiliser companies to be blended in their products.

We have been in contact with a company in Canada, Ostara: www.ostara.com, and a company in Netherlands, Colsen: www.colsen.nl/site/en/.
Ostara has a more complex process which produces granuals and Colsen a more simple approach which makes sand like product.
Colsen offers also a thermophilic digestion process which aims to produce more biogas due to the improved digestion conditions. EWS will set up a pilot plant soon to test its applicability here in Durban. Might be another option for improved sludge treatment in your case.

I am happy to share more information if that might be of interest for you.

Cheers,
Max

Dear Elisabeth,

thanks a lot for your answer and effort. Even the post is a yaer old, the topic is still a current one.

The mentioned difference is really a topic : We are looking for a solution to get gas (and not oil) and a kind of biochar (and most likely one that is free of heavy metals, so that it could be used for phosphorous recycling). But if the heavy metals will get out oft he char and into the process exhaust air depends on the process temperature, that varies a lot between the technologies of the mentioned companies.

We spoke to the company Pyreg at a fair and it seems that they are able to handle the process with suwage sludge, but not sure about the energy bilance and the heavy metal residues in the char.

I also found an intersting article on the German DWA-magazin KA 4/14. On page 272 the wastewater treatment plant Linz-Unkel is mentioned because they are planning to implement a pyrolysis process with flameless oxidation. They have even been in the news: www.general-anzeiger-bonn.de/region/noer...-article1249946.html

I will post if we have more results for our research here. But for now, we unfortunately couldn’t start the planned research project and the planning went back into the hands oft he responsible person from the wastewater treatment plant. But it might be that there will be news in the upcoming months.

We’ll see what time brings.

Cheers,
Sabine

Dear Sabine and all,

Your post is over a year old but it stuck in my mind. I recently got to know an expert on pyrolysis (Gerhard Muggen from the Netherlands) via a webinar we had on 29 April, where pyrolysis was on the agenda (forum.susana.org/forum/categories/98-res...n-usa-and-kenya#8393).

I asked him about pyrolysis of sewage sludge. He sent me the following information by e-mail and has allowed me to post it:

+++++++++

Dear Elisabeth,

We have done pyrolysis of sewage sludge. It is possible, but we have seen following challenges / problems:

• It is costing a lot of energy to remove the water, so not energy efficient.
• The quality of the oil is quite bad. It will be a 3 phase oil (watery phase, thick phase and something in between)
• Quite a lot of N in the oil, leading to high NOx after burning.
• Some minerals go to the ash, which is good. Still some minerals go to the oil which is not good.

For my company the conversion of these wet streams is not interesting for the time being as I focus on streams with a moisture content of max. 50 to 55 % moisture.

Actually we can do any type of biomass. We have done chicken manure, bone residues, sewage sludge and we can make from all streams oil. Problem is that the moisture content is too high to make it feasible. If there would be a sustainable and low cost method to dry this type of biomass it could be interesting.

We currently work with streams not competing with the food chain. For example: wood residues, Empty Fruit Bunch, Sugar cane bagasse, straw, rice husk, corn stover, etc. In that case you have good quality oil which you can use for energy purposes and could be starting material for chemicals.

Kind regards,

Gerhard

Gerhard Muggen
Managing Director BTG Bioliquids BV
Pyrolysis oil, the sustainable alternative! Follow us now on twitter at: www.twitter.com/BTG_btl and subscribe to our newsletter on www.btg-btl.com
PO Box 835, 7500 AV
Josink Esweg 34, 7545 PN
Enschede, The Netherlands
Web: www.btg-btl.com

+++++++++

(one difference is that the product from his pyrolysis process is oil, not biochar; not sure if that has any implications on the maximum possible water content in the input material; edit on 12 May: "There are several ways to do pyrolysis. You have slow and fast pyrolysis and depending on the biomass type and process conditions the share between oil, gas and char is changing and can be changed." (information by Gerhard Muggen) )

Sabine, how did you progress with your research project? You had written:

We are currently looking for companies that offer pyrolysis technology to treat wastewater sludge.

Kind regards,
Elisabeth

Dear all,

I am working for the ingeneering office Kuster+Hager in Switzerland and we are currently looking for companies that offer pyrolysis technology to treat wastewater sludge.

We already found some companies on the internet, some we already contacted, but I would like to know if anyone can share some experiences with that technology (especially high temperature pyrolysis).

We want to support a local wastewater treatment plant where the main responsible person wants to establish some environmental friendly technology to
- Treat the sludge (reduce the amaount)
- Gain more energy (gas)
- Have the possibility to recover phosphorous (without heavy metals)

Phosphorous is a scarce resource that we should recover from the sludge (or sewage sludge ash) and it will be an obligation in Switzerland soon. But the important part is that we are able to remove it without the heavy metals.

If it is possible to find a company that fits to the mentioned ideas, it is planned to establish a research project at the plant.

Can anyone help with this question ? I was looking for companies in Switzerland with only one result, so I checked also for companies in other countries (mainly Germany). I will list here the companies that I found by research on the internet:

- PYROMEX: www.pyromex.com/index.php/de/
- Pyreg: www.pyreg.de/website/resources/documents/pyreg_dt.pdf
- TechTrade GmbH: www.techtrade.de
- DGEngineering GmbH: www.dgengineering.de
- WES Waste & Energie Solutions GmbH: www.WES-gmbh.biz
- Visser & Smit Hanab GmbH: www.visser-smit-hanab.de/
- G&A Gutes Aufbereiten: www.gutes-aufbereiten.de/
- Eisenmann Anlagenbau GmbH & Co.KG: www.eisenmann.com
- UC Prozesstechnik: www.ucgmbh.de/
- Pyrum Innovations: www.pyrum.de/
- Carbolinio : www.carboilino.ch/

Biochar producers :
- Black Carbon: www.blackcarbon.dk/
- Carbon Terra : www.carbon-terra.eu/de
- Rewenergy: www.rewenergy.de/
- Biomacon : www.biomacon.com/

Main question would be if anyone knows companies located in Switzerland as this would be the basis for the research project. Otherwise we need to find other ways.
I’m thankful for any information or advice on this topic!

Thank you very much!
Sabine