Dr. Iván ÑancucheoProfesor AsociadoUniversidad San Sebastián, Concepción

Nuevas tendencias para el tratamiento de drenajes ácidos de minas y soluciones industriales utilizando

reactores sulfidogénicos acidófilos”

In contrast, although sulfur is usually very abundant in natural

and man-made acidic environments, there have been

relatively few studies on sulfur-cycling in these.

Acidophilic iron-oxidisers +

Acidophilic iron-reducers +

Acidophilic sulfur-oxidisers +

Acidophilic sulfate-reducers ?

* Río Azufre; a small,

abandoned sulfur

mine; pH~ 2,3

What is the problem to obtain acidophilic SRB cultures?

• Sulfidogenesis at low pH is a proton-consuming reaction. The pH of

enrichment cultures increases (→ pH ~7) and selects for neutrophiles, not

acidophiles

initial pH: 2.0 2.9 3.5 4.0 4.5

• Lactate as carbon source

pHinternal 6.5

pHexternal 2.0CH3COOH

CH3COO- + H+

Fe-based medium Zn-based medium

sterile overlayer

overlay medium for direct isolation of

acidophilic SRB

underlay inoculated with acidophilic heterotroph AcidocellaPFBC

Selective recovery of transition metals based on the different solubilities

of their sulfide phases

pH 2 pH 4 pH 7

Fe2+ Fe2+ Fe2+ FeS

Zn2+ Zn2+ ZnS

Cu2+ CuS

• many transition metals can be highly effectively removed from mine waters

as reduced sulfide minerals

• the challenge was to make a “clean” products, i.e, free of other metal

sulfides and other minerals such as gibbsite (Al(OH)3)

Acidophilic sulfidogenic system operates as an

Upflow Biofilm Reactor (UBR)

Packed bed(immobilized SRB)

pH electrodeFeed in(pH 1.5-4)

Effluent out(pH 2-5)

meterpump

4 C3H8O3* + 7 SO4

2- + 14 H+ → 12 CO2 + 7 H2S + 16 H2O

H2S + Me2+ → MeS↓ + 2 H+

Acidophilic sulfidogenic reactor performance data :

Mynydd Parys AMD, Wales, UK

Analyte Concentration

(mg/L)

SO42- 2750

Fe2+ 280

Al3+ 90

Mg2+ 80

Zn2+ 70

Cu2+ 45

Ca2+ 42

Na+ 15

Mn2+ 10

NH4+ 1.8

(pH 2.1)

Objective: selective removal of copper (as CuS)

Acidophilic sulfidogenic reactor performance data:

Mynydd Parys AMD

Acidophilic sulfidogenic reactor performance data:

Cwm Rheidol AMD, Wales

Analyte Concentration

(mg/L)

SO42- 1162

Fe2+ 167

Al3+ 13

Mg2+ 48

Zn2+ 196

Cu2+ trace

Ca2+ 20

Na+ 12

Mn2+ trace

(pH 2.5)

Objective: selective removal of zinc (as ZnS)

• Fed characterized by extremely low pH (2.1) and zinc and iron as main transition metals (0.5 and 2 mM, respectively)

• The sulfidogenic system (2.3 L) was operated as a continuous flow mode unit for 99 days at 30°C

Simultaneous removal of Zn and Fe for treating acidic

mine water (Río Azufre; Arica y Parinacota Region)

Zn

GlycerolpH

Fe

Glycerol remaining

Flow rate

Acetate

Bacteria

Sulfate removal from extremely acidic wastewater* using the

acidophilic SRB bioreactor

Measurements correlate well with theoretic chemical stoichiometries

*pH 1.6 – 3

20 mM (~2 g/L) sulfate

no transition metals

0

10

20

30

40

50

60

70

80

0 20 40 60 80 100 120

Time (days)

Su

lfate

(m

M)

1.25

1.3

1.35

1.4

1.45

1.5

pH

feed pH

Sulfate in effluent

Sulfate added

4 C3H8O3* + 7 SO42- + 14 H+ → 12 CO2 + 7 H2S + 16 H2O

pH 1.45 – 1.3

~ 55 to 70 mM sulfate (~ 6.7 g/L)

no transition metals

Raffinate:

Packed bed(immobilized SRB)

pH electrodeFeed in(pH 1.6)

Effluent out(pH 3)

meterpump

H2S → S0

At. ferrooxidans

Net reaction: SO42- + glycerol → S0 + CO2

Where does the H2S go?

SO42- → H2S

As5 in acidic solutions ?

Dr. Ivan Nancucheo

Universidad San Sebastián,

Concepción

Phone: + 56 9 4910 1205

inancucheo@gmail.com

Muchas gracias

Sabrina Hedrich; BGR, Germany

Gordon Southam; University of Queensland

Guilherme Oliveira, ITV, Brasil

Walter Mac Cormack; Instituto Antártico Argentino

Alex Schwarz; Universidad de Concepción

Pedro Galleguillos; CICITEM