Electrochemical Methods for Wastewater TreatmentS. Hild, C. Abt, R. G. Simon, A.-D. Steinkamp, M. Stöckl, K.-M. Mangold | hild@dechema.de

DECHEMA-Forschungsinstitut, Theodor-Heuss-Allee 25, 60486 Frankfurt, Germany

Electrochemistry

Re-Salt: Recycling of Industrial Salt-laden ProcessWater www.resalt.web.th-koeln.de

01.10.2016 – 30.09.2019; Funded by: BMBF

RADAR – Wastewater treatment with Radicals

Goals and Approach:

• Removal of persistent micropollutants in situ

• Development of a scalable electrolysis cell

• Energy-efficient and on-demand wastewater treatment

• No further need of chemicals

• Synergetic operation of a gas diffusion electrode (GDE) and boron doped diamondelectrode (BDD)

H2O2O3

M

e

m

b

r

a

n

e

+

BDD

GDE

-

O2

H2O

OH.

Cell

Mixing-reactor

H2O

Micropollutants in wastewater

O3 + H2O2 → 2 OH• + 3/2 O2

+ ‒

ElektroWirbel: Closing of Industrial Material Cyclesby new Electrochemical Magnetically StirredReactors www.dechema-dfi.de/ElektroWirbel.html

01.09.2016 – 31.08.2019; Funded by: BMBF

First time combination of a magnetically stirred reactor with electrochemical polarization. • Elimination of organics from salt containing waste water• Electrochemical regeneration of the deployed magnetic particles• Regained feedstocks can be returned in the economic cycle

Electrochemical magnetically stirred reactors offer a high innovationpotential in other scopes • Elimination of trace substances in sewage plants• Processing brackish water / water softening• Treatment of particle and/or fiber containing medias• Recovery of valuable materials like heavy metal ions• Microbiological / electro organic electrosynthesis

KEStro: Wastewater Treatment Plants

as Stabilizers for Power Grids www.kestro.de

01.05.2014 – 31.07.2017; Funded by BMBF

• Balance of supply and demand in power grids needed due to increasingamount of renewable energy

• Waste water treatment plants as stabilizers for power supply systems

• Energy demand: microorganisms produce energy from organic substances in waste water in a microbial fuel cell (MFC)

• Excess energy: 3-step process for the elimination of micropollutants from waste water by electrosorption and electrolysis

The chlor-alkali electrolysis counts as the most important industrial processfor the production of Cl2 and NaOH. An increasing Cl2 demand worldwide isthe consequence of the rising plastic production. The resulting process wateris salt-laden but insufficiently concentrated and contaminated with organics.Hence, for a recirculation of the wastewater several limitations have to beovercome.

The joint project focusses on the following aspects:

• Purification: Development of efficient purification techniques for the removal of trace substances

• Concentration: Re-concentration of the clean salt-laden water resulting in pure water and highly concentrated saltwater

• Analytics: Introducing offline and online analytics for trace substances in saltwater

Excess energy:Elimination of

micropollutants

Energy demand:Microbial fuel cell

O2

ano

de:

bio

film

cath

od

e: G

DE

H2O

CO2

waste water

RADAR: Wastewater Treatment with Radicals www.machwasmaterial.de/RADAR.html

01.04.2017 – 31.03.2020; Funded by BMBF

Goals and Approaches

H2O2O3

M

e

m

b

r

a

n

e

+

BDD

GDE

-

O2

H2O

OH.

Cell

Mixing-reactor

H2O

Micropollutants in wastewater

O3 + H2O2 → 2 OH• + 3/2 O2

• In situ removal of persistent micro-pollutants(e.g. pharmaceuticals)

• Development of a scalableelectrolysis cell

• Energy-efficient and on-demandwastewater treatment

• No further need of chemicals

• Synergetic operation of a gas diffusionelectrode (GDE) and boron dopeddiamond electrode (BDD)

Main Characteristics of a BDD

Scan rate: 0,1 V/s; 0,01 M H3PO4

Electrode area: 9cm²

• p-type semiconductor

• High overpotential for oxygen and hydrogen evolution in aqueous electrolyte

• Polycrystalline surface

10µm

SEM – pictureCyclovoltammogram

(Pattern: KIT)