The 13th IWA Leading Edge Conference

on Water and Wastewater Technologies

Workshop 6

Microalgae Based

Wastewater Treatment Facilities:

Progress, Experiences and

Perspectives for the Next Years

HARVESTING IN A SUSTAINABLE WAY?

13-JUN-2016

Robert Reinhardt Algen, algal technology centre, Slovenia

2

BACKGROUND

Albaqua Cornet project – pilot scale

treatment of paper mill wastewater

Excellent results in 6 month operation

AlgaeBioGas Eco-innovation project – algal

treatment of biogas digestate

Demonstration plan operating for 2 years

Liquid phase

Algal bacterial biomass used for biogas

Saltgae H2020 project – treatment of salty

wastewater from food industry (Algae, AD,

RO)

Just starting

Hydrocyclone preconcentraion

3

PROCESS CONTEXT

Pre-treatment Algal-bacterial

treatment

Downstream processing

WW Treated water

Harvesting

Algal-bacterial biomass

Energy Nutrients Algal

products

4

PROCESS OBJECTIVES

Energy recycling – positive energy balance

Eliminate aeration cost & energy consumption

Nutrient recycling

One stage for secondary & tertiary treatment

Avoid conversion of COD to GHG

Consume CO2 instead of releasing it

Heavy metals & “heavy” organics

Produce useful biomass

Salt-tolerant treatment

5

HARVESTING & DOWNSTREAM

Clean water

Dewatered

Dry

Fractioned

Biomass

Heavy metals

Hard organics

Bio-adsorbents

Nutrient recovery

Energy recovery

Salt

Objectives

Water content

C : N ratio

Biogas substrate

Lipids

HTL

HTC

Gasification

Biofuels

Nutrients

Fitostimulants

Organics

Fertilizers

Animal feed

Bioplastics

Adsobents

Fillers

Other

Purpose

Water content ~ 1:1000

Particle size

Particle density

Salt

Bioflocculation

Cost

Energy

Use of chemicals

Pathogens

Challenges

Sedimentation

DAF

Filtration

Electrofloculation

Centrifuge / Decanter

Hydrocyclones

Combination/multistage

Technology

Harvesting & dowstream

6

OBJECTIVES

Clean water

Dewatered

Dry

Fractioned

Biomass

Heavy metals

Hard organics

Bio-adsorbents

Nutrient recovery

Energy recovery

Salt

Objectives

Always, no tertiary treatment

Much more biomass comapared to aerobic sludge

Energy?

Deposit – incineration?

Fertilizers

Positive energy balance

Biorefinery

To what extent

Desalination, reflux, energy extraction

7

BIOMASS PURPOSE

Water content

C : N ratio

Biogas substrate

Lipids

HTL

HTC

Gasification

Biofuels

Nutrients

Fitostimulants

Organics

Fertilizers

Animal feed

Bioplastics

Adsobents

Fillers

Other

Purpose Energy?

Fertigation?

Suitable for biogas? Additional substrates

Water is the enemy

Stressing? Lipid content?

Moderate dewatering

Treatment of the liquid phase?

Slow release fertilizers - popularity?

Lack of knowledge

Heavy metals

Toxic species, pathogens

Biodegradable – Renewable substrates

Protein content

Fate

High value?

8

CHALLENGES

Water content ~ 1:1000

Particle size

Particle density

Salt

Bioflocculation

Cost

Energy

Use of chemicals

Pathogens

Challenges

Move 1 ton of water to get 1 kg biomass

Size & shape resist filtering

Algal density = water density

Salt is not assimilated

Species that bind to others – a dream

Compare to sedimentation

Interrelated

Same as aerobic treatment

9

TECHNOLOGY

Sedimentation

DAF

Filtration

Electrofloculation

Centrifuge / Decanter

Hydrocyclones

Combination/multistage

Technology

Best if it works

Unreliable

Very good results

Depends on the species

Costly

Good results

Possibly second stage

Possibly first stage

Might be required

10

SEDIMENTATION

11

BIOFLOCCULATION

12

ELECTROCOAGULATION

13

DISCUSSION

Energy and cost efficiency of harvesting

Bio-flocculation – can we control it?

How can we treat salty water?

Can we release water with algae to the environment? Is

C/BOD for algae a true C/BOD?

Regulatory aspects of releasing algae.

14

ALGAEBIOGAS

Welcome to visit AlgaeBioGas demonstration centre in

Ljubljana, Slovenia

15

THANK YOU

Robert Reinhardt

AlgEn, algal technology centre

Ljubljana, Slovenia

http://algen.eu/

http://algaebiogas.eu/

robert@algen.si