Biomethane Low Impact Production and Carbon

Dioxide Bio-Capture for Circular Economy

G. D’Imporzano, F. Adani

Project objectives:

Develop an innovative system for biogas upgrading to bio-methane and

suitable for CO2 recovery, by nanoporous materials,

Develop strategies that maximize the mass transfer and use of CO2 for

the cultivation of microalgae with the ultimate goal to produce

sustainable local high quality protein by recovered CO2 and digestate

LOMBARDY DISTRICT

Lombardy has more than 800 biogas plant treating slurry , manure and energycrops.

Producing digestate, biogas (methane CO2) and heat

CO2

Digestate richin nutrients

Microalgae(local quality protein, added value protein)

Biogas purification

BiomethaneAdvanced Biofuel

Feed

LOMBARDY DISTRICT

Lombardy is a region of intensive farming (livestock)

the net input of feed from extra region (e.g. soymeal) causethe import of 60.000 tons of nitrogen per year (EUROSTAT).

Finally Lombardy produce manure and slurry equal to 38million m³/year, thus 140.000 tons of nitrogen….

The use of chemical N fertilizers (e.g urea) cause theadditional input of 100.000 tons/year of nitrogen in thesystem.

High photosynthetic efficiency (up to 20% of PAR, 10% glogal)High areal productivityHigh nutrient uptakePossibility of carbon fertilization

MICROALGAE

Koller et al 2014

MICROALGAE VALUABLE COMPOUNDS

Nanosponge: innovative CO2 capture and biogas upgrading

Low energy for separationEasy systemComplete regeneration of after useLow production costsTRL 5-6

Nanosponge: innovative CO2 capture and biogas upgrading

Low energy for separationEasy systemComplete regeneration of after useLow production costsTRL 5-6

Arthrospira platensis, generally known asSpirulina, is a microalgae rich in protein (60-70%), vitamins e pigments used as dietsupplement and now exploited as feedadditives

ARTHROSPIRA PLATENSIS

OBJECTIVES OF THE STUDY

To replace chemical fertilizer by digestate based nutrients in the cultivation of spirulina

To reduce or substitute the use of NaHCO3 by the alkalinity of ammonia present in the digestate

To increase CO2 uptake thanks to lower pH set up

To reduce the loss of ammonia (ammonia stripping) keeping lowerpH in the culture medium

Obtain significant production

Parameters

pH 8.68

TS (g kg-1)

TKN (mg kg-1)

1.23±0.5

4000± 15

N-NH +(mg kg-1)4

COD (g L-1)

P (mg kg-1)

3900± 10

11± 1

127± 9N-NH4+~150 ppmN-NH4+~ 4000 ppm

UDF

Ultra Filtrated Digestate

Trials set up

STEP WISE

Results

STEP WISE

Results

STEP WISE

It is possible to replace chemical fertilizer by digestate basednutrients in the cultivation of spirulina, using a step wisesupply

It is possible to reduce the use of NaHCO3 by the alkalinity of ammonia present in the digestate

It is possible to grow spirulina at pH 8-8.5 and increasing the CO2 uptake and production (increase in photosinteticefficiency)

To reduce ammonia volatilization step wise addition and higher pH are needed

FINDINGS

Scenedesmus acutus, Tetradesmus obliquus

High yield and effective N recycling

Robust strain thriving in wastewaterenvironment

Scenedesmus acutus

Trials set up

Results

Results

FINDINGS

Scenedesmus acutus actually thrive on digestate

higher CO2 addition ( lower pH) increase the nitrogen uptakeand and total photosintetic efficiency

Ammonia volatilization is reduced by lower pH and effectivealgae growth

Quick growthRobust strain

Chlorella

Results

FINDINGS

Chorella grow on digestate

higher CO2 addition ( lower pH) does not bring good results

Ammonia volatilization is reduced by step wise addition and high grow rate

The EU regulation 767/2009 states that these materials cannot be used as feed ingredients: Faeces, urine and separated digestive tract content

All waste obtained from the various phases of the treatment of the urban, domestic and industrial waste water.

there are relevant legislation for the recovery of nutrients in production purpose:

1069/2009. ex (1774 directive) on disposal and reuse of animal by-products it is stated that the reuse of animal byproduct should be supported (The disposal of all animal by-products is not a realistic option).

Quality of products and compliance with regulation

• manure shall be used for the manufacturing of organic fertilisers or soil improvers to be placed on the market in accordance with Article 32 following processing by pressure sterilisation, when applicable, and permanent marking of the resulting material;

• alternative methods of use and processing of manure can be authorised (different from pressure sterilization) The procedure for authorisation of an alternative method of use of animal by-products be initiated either by the Commission or by a Member State or by an interested party, …the European Food Safety Authority (EFSA) will be involved in evaluation

• Changes can be made in the legislation according to technological progress: Progress in science and technology may lead to the development of processes which eliminate or minimise the risks to public and animal health. Amendments to the lists of animal by-products set out in this Regulation should be possible, in order to take account of such progress.

Quality of products and compliance with regulation

• pig slurry or digestate often exist where thermal energy is available and can be used to sterilize slurry. In alternative membrane based technology such as Ultra filtration combined with reverse osmosis (UF+RO we have several for digestate treating ) can assure no microorganism pass the treated material. These points may open to consider the thermal treatment or UF and RO process as suitable treatment for the production of fertilizers.

• The new draft on FERTILISING PRODUCTS REGULATION, under revision states for instance that digestate, even coming from organic waste (no sludge of from civil wastewater) can be used for the production of fertilizers if :

• No Salmonella sp. in 25 g sample

• Less than 1000 CFU/g fresh mass for E. Coli

Quality of products and compliance with regulation

Waste Manag. 25 (1), 417–425, 2005

E. coli

Hygienisation in AD

1 ha cultivated with maize 0.54 ton/ha N

Nutrient recovery1 ha cultivated with algae 2-3 ton/ha N

Sustainability: What has a price?Who decides?Who pay?

Termodynamic is a fact

Economy is an agreement

Physic and termodynamic boundaries

CO2 in the atmosphere

N and P in water

Energy in a system

….

Physic and termodynamic boundaries

CO2 in the atmosphere

N and P in water

Energy in a system

….

LCA: un vantaggio per chi?

0%

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100%

No recovery Nutrient and carbon recovery

Impact of production and recovery of nutrients

Sustainability: a change of culture

Thank you for your attentionand your questions.

DiSAA - Università degli Studi di Milano

Lab. Suolo e Ambiente, Lab. Biomasse e Agroenergia, Lab. Bioeconomia e

Chimica Verde

Via Celoria, 2 20133 Milano

Tel. 02-50316543, Fax. 02-50316521

Web site: http://users.unimi.it/ricicla/

Giuliana.dimporzano@gmail.com