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Application of iron nanoparticle to wastewater treatment

Mauro Zanette – Lecher Ricerche & AnalisiStefano Zuin – Venice Research Consortium

Antonio Marcomini – University Cà Foscari VeniceNicola Levorato – Depuracque Srl

Venice, November 23 th

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� Introduction� The Depuracque group� Concept & Study objectives� Planned activities� First results� Final consideration � Contact details

Outline

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Introduction

According to the 2nd Dissemination Workshop of the EU Nano4water cluster:

Nanotechnologies (NTs) can be applied to (waste) water treatment exploiting existing/newly developed nanomaterials (NMs) to develop promising separation, purification and detoxification technologies (NMs as adsorbants of specific contaminants or catalysts in degradation reactions).

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Introduction

Although several applications of NTs to water treatment have been successfully demonstrated at the laboratory scale, most of them:

�require validation of efficacy/efficiency in the field, and�are still far from market.

In addition, there is a wide debate, including both scientists and public, about the safety of NMs, especially their potential impact on environment and biota.

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The Depuracque group

• Design and construction of wastewater treatment plants:

Over 1500 plants in 40 years combining chemical-physical & biological tech. (SBR/MBR), ultra-filtration, reverse osmosis, vacuum evaporation, stripping and absorption;

Proprietary technologies and patents in landfill leachate treatment and solid waste inertization and decontamination.

• Industrial waste/wastewater treatment :

Two operation plants in Italy, 340KT/year treatment capacity.

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The Depuracque group

• Environmental contamination assessment and remediation projects:

Soil and groundwater decontamination using on-site technologies and mobile treatment plants;

•Analytical and Research Laboratory

Providing monitoring, sampling, chemical and microbiological analysis and consulting services for water, waste and emissions in the environmental, food and industrial sectors.

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The Depuracque group

The company has recently started research activities aimed at

(i) investigating possible application of NTs to wastewater treatment and groundwater decontamination;

(ii) developing analytical tools and protocols to detect NMs in wastewaters.

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Concept

It’s well recognized that treatment of landfill leachate, which is one of the main pollutants of soil and water resources, is of great importance as discharge regulations and standards are becoming more and more stringent.

As a result, today there is increasing interest in developing new and more efficient technologies for treatment of landfill leachate.

Depuracque owned/licensed plants treat more than 100KT/y landfill leachate

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Concept

Advanced oxidation processes (AOPs) are widely used within the wastewater treatment. Most of the AOPs use a combination of strong oxidants like ozone, oxygen or hydrogen peroxide with catalysts like transition metals, irons, etc. Typical AOPs includes e.g. O3/UV, H2O2/UV, H2O2/Fe(II).

The catalysis of hydrogen peroxide by ferrous sulfate, Fenton’s reagent, is one of the most common AOPs. The oxidation of organic compounds by Fenton’s reagent may proceed by the following chain reactions (Zhang et al., 2005):

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Concept

Since 1990s different research activities have been focused on the treatment of landfill leachate by Fenton process. Fenton process was used as a post-treatment or pre-treatment because the removal of bio-refractory organics in leachate with direct biological treatment is vey hard.

The effectiveness of Fenton’s reagent (H2O2, Fe(II)) has been widely demonstrated for the treatment of municipal landfill leachate (COD reduction up to 80%).

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Study objective

To investigate the effect of zero valent iron nanoparticles (nZVI) as iron source in Fenton process:

1. for reduction of the organic load in landfill leachate (i.e. reduction of COD), and

2.for improving biodegradability of leachate (i.e. increase of BOD5/COD ratio)

May Fenton process with nZVI be applied as a pre-treatment before final biological treatment ?

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Planned activities

To investigate the effect of nZVI as Fenton reagent for COD reduction, the following tasks were planned:

1. State of the art on “organic load removal of landfill

leachate by fenton process using nZVI

particles”

4. Batch experiments to quantify COD reduction and to investigate BOD5/COD

ratio.

2. Characterize landfill leachates collected and

processed by Depuracque

3. Definition of experimental protocol to verify COD

reduction and BOD5/COD ratio

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Planned activities

1. State of the art on “organic load removal from la ndfill leachate by fenton process using nZVI particles”

Based on literature data available, we have identified parameters affecting Fenton process:

• reaction time

• pH

• H2O2 to Fe(II) molar ratio

• Fenton’s reagent dose

• temperature

• COD

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Planned activities

Wastewater COD (mg/L)

nZVI added (mg/L)

H2O2added (mg/L)

H2O2 / COD

H2O2 / Fe

pH T (°C)

COD reduction (%)

t (min)

Chu et al., 2012

Cooking 8400 3000 102001.21-1.36

3.4 2 – 4 25 70% 60

Shafieiyoun et al., 2011

Landfills 38000 7000 91800 2.42 39 2 40 75% 30

Selected examples of literature data

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Planned activities

2. landfill leachate used for tests:

Origin: Closed municipal waste landfill - Veneto region, Italy

• pH 7,8

• COD 2500 mg/L

• TOC 465 mg/L

• electrical conductivity 13200 µS/cm

• TSS 320 mg/L

• BOD20 305 mg/L

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Planned activities3. Definition of experimental protocol

Experiment details

Leachate 500 mL; two sample, with or without pre-treatment

nZVI 0.1 – 10 g/lNANOFER STAR and NANOFER OX ( Nano Iron company)

pH Adjusted to 2.5 value by H2SO4

H2O2 / Fe molar ratio

5 – 40

Temp. 22 °C (indoor lab)

Reaction time 1 hour

Mixing By a variable speed motor connected to coated steel shaft and three blade propeller

Sampling Sample (5 ml) taken at pre-selected time intervals with syringe for analysis

Analysis COD, BOD5, TOC (to eliminate the remaining H2O2 and stop the oxidation reaction Catalase enzyme is used)

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Planned activities

3. Definition of experimental protocol

nZVI

H2O2

Leachate

pH controller

Acid (H2SO4) Base (NaOH)

Agitation

Schematic rapresentation of experiment

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Planned activities

3. Definition of experimental protocol

Aqueous dispersions of nZVI were prepared.

Stability over time of aqueous dispersion of NANOFER STAR

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Planned activities

3. Definition of experimental protocol

NANOFER STAR

Air-stable surface stabilized nZVI powder

http://www.nanoiron.cz/

NANOFER OX:

Ferrate powder (ferrate = iron in high oxidation state)

Characterization of both samples

are on going.

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First results

nZVI dose (with 5 g/l H 2O2)

0.2 g/l 0.8 g/l 1.6 g/l 5 g/l 10 g/l

COD reduction (%)

25 30 35 50 65

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Final considerations

•COD reduction by using NANOFER STAR ranged 25% - 65 % on the basis of reagent dosage.

•This technique is fast as COD removal is achieved i n the first 15 min of reaction.

•Quantification of BOD5/COD are on going.

Next step: evaluate new landfill leachates and inves tigate the effect of NANOFER OX for enhancement of Fenton reac tion.

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Contact details

Mauro Zanette , PhD

Lecher Ricerche e Analisi s.r.l. s.u.

Cell +39 366 6373343

Tel +39 041 5745699

Fax +39 041 5745525

via Roma n. 145 30030 Salzano (VE)

www.lecher.it

www.depuracque.it

Thank You very much for your attention.