1. ExcellenceAVA Green Chemistry Development (AVA) offers advanced technologies for the treatment of biomasses and waste streams, based on the hydrothermal treatment technology (HTC). This technology allows the recovery of the most important ingredients such as potassium, calcium, magnesium, nitrogen, sulphate and the finite resource phosphate as fertilizer (fertilizer production) while simultaneously producing high quality biocarbon or activated carbon e.g. as soil improvement. We call this integrated approach HTCycle, showing hydrothermal carbonisation as a platform technology for the circular economy with a zero waste approach.

2. Objectives using the example of sewage sludgeAVA aims to increase the amount of sludge converted into high value products such as fuel, activated carbons for water treatment, recovered phosphorus, soil remediation material, carbon sequestration schemes and other applications. The HTCycle process turns the present sewage sludge disposal (incineration) from a costly process into an income-generating activity.

HTC consists in applying high temperatures and pressures to biomass in the presence of water, which results in two main products: a coal-like product (HTC-coal) and water-soluble products. This process allows converting different wet biomass streams, such as sewage sludge, into fuels and other substances of industrial interest including a nearly 100 % recovery of phosphorus. The expected outcomes of HTCycle are the creation of a new business pathway in the upgrade of sludge into new resources using HTC, which will pave the way to provide economically attractive and environmentally friendly alternatives to utilization of what nowadays is considered a difficult waste.

In summary, the following are the general objectives of HTCycle:

Introducing the HTC technology in the market as a circular solution for sewage sludge reuse in the wastewater treatment sector worldwide.

Encouraging resource efficiency by upgrading sewage sludge into valuable products using HTC and by the recovery of raw nutrients and phosphorous.

Reducing greenhouse gas emissions on treating sludge. Increasing choices for European WWTPs by offering them a new alternative for the sewage

sludge disposal solution. Disseminating and promoting knowledge on the economic and environmental advantages of the

HTC process in the sewage sludge disposal sector. Turning wastewater management into a more sustainable activity by reducing the incineration of

the sewage sludge.

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Figure 1. HTC transforms sewage sludge into new products

3. Concept and methodology

3.1.ConceptBy means of hydrothermal carbonization, wet biomass e.g. sewage sludge with 25% total dry matter is converted into carbonaceous solids at relatively high yields in water, with pressure and temperatures at the lower region of the liquefaction process. The lack of need for energy-intensive drying before the process opens up new possibilities for sewage sludge as feedstock for this technology, producing hydrochar and carbonaceous liquids, high value products that can be used as fuel, activated carbons for water treatment, soil remediation, carbon sequestration schemes and as raw material applications.

Current stage of development of the innovation using the example of sewage sludge

AVA has been developing and testing its advanced HTC technology in a modular pre-industrial HTC plant with a capacity of 20,000 tons/y. The prototype is located in Relzow, Germany and it had been. The technology is entering into commercial exploitation for other wet biomass waste streams, such as agricultural and forestry residues. AVA carried out tests with sewage sludge which have shown satisfactory results. The tests comprised the carbonization of 200 tons of sewage sludge, with 75% moisture, from the neighbouring municipality of Karlsruhe. The products (1t) yielded a solid phase, HTC-coal or carbon, composed of 40% C, 2% N and 5% H (in weight) and a liquid phase that can be further treated by the wastewater treatment plant. The latest analysis of the products (bio-coal, black carbon) obtained, carried out by well-known laboratories such as, Fresenius and Synlab, have confirmed their high quality and the destruction of harmful compounds, such as dioxins, and endocrine disruptive substances. AVA detected some technical barriers during the testing, such as the need to build a waste water treatment plant, and the drying of the HTC-coal. AVA has already designed the solutions required to optimize the process regarding sludge treatment. Also, preliminary analysis of the liquid phase obtained shows, that it can either be recirculated to the wastewater treatment plant or, reused as fertilizer. Furthermore there has already obtained the permit for water discharges from the municipality. The AVA-HTC process is as safe in this regard as incineration.

AVA will apply with these improvements in order to evidence the suitability of HTC as an optimal sludge disposal and resource recovery pathway. As an advantage, all needed licences and permissions are already existing for this location. For closing the loop, sludge of the local WWTP will be treated and transformed into HTC-coal (used for process energy), activated carbon (used for water purification) and recycled phosphorus.

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Figure 2. HTCycle and combination with renewables to generate the needed HTC process energy

The wastewater treatment service provider will have reduced sludge disposal costs, a proven method of phosphate recovery and an additional water treatment step (removal of endocrine disruptive substances such as hormones and antibiotics).

Figure 3. HTC plant process diagram

In general the AVA HTC method in application is focusing on several valuable products depending on the feeding material and ingredients:

Solid phase:HTC-Coal for energy production & storage : AVA HTC-coal has many advantages: it is a CO2

neutral fuel, it contains a high calorific value - approx. 25 MJ/kg (HHV) and has very good combustion properties, the remaining ash has a very high melting point and it is a stable product for storage and transportation. The coal produced during the activities could be used to generate the needed HTC process energy or as …

Activated carbon adsorbents : this selected and activated HTC-coal has been successfully designed via the hydrothermal process for the removal of micro-pollutants (e.g. hormones, antibiotics, heavy metals) from water. The current market prices of activated carbon range between 200 and 2,000 €/ton. The activated carbon produced during the activities could be used in the nearby WWTP to have an additional water polishing step before releasing it to the environment or as …

Hydrochar: this selected and micro-bacterial activated HTC-coal is comparable with Terra Preta because both are mixtures out of several substances can activate and enhance the soil. Terra Preta increase micro-bacterial activity and biodiversity wherever it is used like our product. Only Terra Preta and hydrochar are able to immobilize Nitrogen into the soil but not for the plants or the roots. The current market prices of hydrochar range between 200 and 1,000 €/ton.

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Liquid phase:Separation and recycling of phosphorus : during the HTC process, AVA will separate, in a patented process step, the phosphorus from the incoming sewage sludge as phosphoric acid. The phosphorus recovery efficiency rate of this process is around 85 %.

Separation and recycling of nutrients: during the HTC process, AVA will separate the ingredients such as potassium, calcium, magnesium, nitrogen, sulphate in different ways like precipitation, membrane filtration or stripping.

with chemical P-elimination

Parametersewage sludge (feeding

material)HTC process water

HTC-coalHTC-coal (phosphorous reduced)

HTC leaching water

c / g/kgDM n / % n / % n / % n / % n / %

Phosphorous 34 100 3 97 3 94

Nitrogen 43 100 70 30 19 11

Sulphur 9 100 47 53    

Pottasium 4,1 100 35 65 59 41

Calcium 44 100 2 98 90 10

Magnesium 6,6 100 7 93 26 74

Figure 4. HTC process chain with yields / ratio

AVA has made an estimation of the potential incomes from these main products that could be gained from a plant processes 15,000 ton of dry biomass / year depending on feeding biomass

Products Production Unitary price (€/t)Estimated incomes

(€ /y)

HTC-coal 8,000-10,000 t/y dry matter

220 €/t dry matter (gate fee) 1,760,000 -2,200,000

Alternative:Activated carbon 2,500-4,000 t/y 500-2,000 depending on the

quality of the coal1.25-8.0 million (replaces

HTC-coal revenue,

Alternative:AVA-hydrochar

16,500-18,500 t/y 200-1,000 depending on the quality of the coal

3.3-18.5 million (replaces HTC-coal revenue

Phosphate 1,000 t/y 400-500 400,000-500,000In addition to HTC-coal

revenue

Nutrients 500 t/y 100-500 50,000-250,000In addition to HTC-coal

revenue

Figure 5. HTC products

After 6 years of HTC technology a new design of the plant is engineered. It will reduce power consumption by 40% and increased yield by 30%. Integrated with pre-treatment and post-treatment modules and additional modules for an integrated resource management.

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The main parts of the new HTC process designed by AVA in Relzow, among others, includes a phosphorous recovery unit (85 % recovery), a software and hardware unit to automatize and control the plant, the main plant (which includes reactor, pumps, valves, etc.), a flue gas cleaning technology and a treatment/reuse plant for process water.

Figure 1. The New HTC Core Technology 3D-design

3.2.Political situation and ambitionThe trend in the sector is decidedly towards an increase in incineration, abandoning other methods: from the 1,779.96 thousands of tons of sludge produced in Germany in 20101, 53% were incinerated, mostly in mono-combustion systems. In the other countries, spreading on soil is still the predominant disposal method, although it is expected that, due to the concerns about high mercury and heavy metals content, as well as endocrine disruptive substances, the sector follows the trend set in Germany and other countries, such as Switzerland (forbidden since 2006) and Austria (forbidden in Tirol and Salzburg) towards more restrictive legislation against the use as fertilizer and a wider use of incineration.

HTC is a solution for this widespread problem: it is a safe and economic way of disposing of the sludge, and will yield a product that has a high value in the market.

Novelty of the innovation business project and key market application of the result

The main disposal method for sewage sludge nowadays and the present trend for the future is incineration. Other methods (as soil conditioner), although more moderate in costs, have raised serious health and environmental impact concerns and are being phased out, which leaves incineration as the only available option. As it has been explained before, incineration is neither technically nor economically efficient: disposal fees keep rising steadily, in some regions even beyond the 100€/ton of dewatered sludge, as incineration plants have to comply with more restrictive legislation with regard to emissions and as wastewater treatment plants find themselves with no other option for disposal. The innovation of the present project lies in the introduction of a new sludge disposal method that is competitive against incineration on the technical, safety and economic areas, bringing new actors to the sector and ensuring, through this new use of HTC, a stabilization of the sludge treatment prices. Moreover, HTC not only disposes the sewage sludge, but also, it uses it as the feedstock to produce valuable products, which can be sold and provide an additional income for the HTC plant operator. In this sense, HTCycle aims to change the industry of sludge disposal, into a sector that provides valuable products to other industries.

Advantages against incineration and added value for customers1 EUROSTAT, 2014

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HTC has lots of advantages comparing with the current main technology available: incineration. The first advantage of HTC against incineration is economic: the disposal of sewage sludge with HTC will entail lower costs than incineration and therefore, the price per ton disposed will be significantly lower: a preliminary estimation by AVA-CO2, based on the results of their tests, situate the price at 50€/ton disposal costs compared to the 80-110 € of incineration.

The HTC method dewaters wet biomass more efficiently than any other technology. According to a study performed by the Zurich University for Applied Sciences (Switzerland), the HTC process saves up to 61% thermal energy and up to 69% electrical energy compared to traditional thermal drying methods.

Finally, the multi-batch system developed by AVA is modular (e.g. modules of 50,000 tons of sludge), which has the advantage of being able to adapt to the growth of industry and/or a population at a reduced cost and effort. This characteristic of the plant, improves the economic feasibility in places with low sewage sludge production or seasonal sewage sludge production.

Improvement potential over time

AVA continuous efforts in research and improvement of the HTC technology will allow a further improvement of this technology. There is also potential for the development of obtained products, as varying the parameters in the process can result in new products with applications not yet explored.

The HTC process also brings environmental benefits. According to a study of the ZHAW, the combustion of coal-HTC in a lignite power plant is particularly suitable for the reduction of greenhouse gas emissions, ecotoxicity and radioactive waste. The replacement of fossil fuels by HTC-coal and the associated reduction of greenhouse gas emissions were also investigated in a recent study by Vogt & Fehrenbach (2012). They identified a big potential for climate protection in the replacement of fuel oil by HTC-coal in the auxiliary firing of sludge incineration plants in the state of Berlin.

Other advantages regarding HTC technology may include:

Waste heat can be used in the HTC process Use of green electricity generated with sewage gas for HTC process Especially Phosphorous but also nutrients recovery and recycling. Reduction of fossil fuels use (as HTC-coal substitute them)

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Figure 6. Sewage sludge disposal methods in the EU (Emscher Genossenschaft Lippe Verbrand (EGLV) 2006)

3.3.The companyAVA is a technology based company situated in Relzow, Germany. Its professional team counts with more than 30 years of experience in HTC, management and energy projects. As one of the pioneers in the industrial application of this innovative HTC process, thanks to the effort done in research and development in this technology since 2009, AVA can provide solutions for the treatment of multiple types of biomass in order to produce a solid biofuel. AVA holds 17 patents for equipment and major HTC plant systems. Due to AVA expertise in both industrial development and construction of industrial plants of hydrothermal carbonization of wet biomass in multi-batch process, AVA can offer its customers a wide range of services, from the elaboration of feasibility studies for treatment of biomass streams through HTC, to the supply and installation of turnkey hydrothermal carbonization plants and finally to a great range of after sales services such as technical support, maintenance, technical training of staff and sales support for HTC products.

AVA supports cooperation with the most important Universities and Institutes in Europe.

ZHAW Zürch, CH (Engineering) UHOH Stuttgart, GER (Agriculture, Research&Development) Fraunhofer Institut Germany, GER (Engineering) KIT Karlsruhe, GER (Technology, Scale-up) a.s.o.

signed Stepan Kusche

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