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heavy metals removal from sewage
1. HEAVY METALS IN
WASTEWATER
>> REMOVAL
B Biological methods
Submitted by :
MANISH AMAN
2014UCE1538
Submitted to :
Prof. A. B. Gupta
sir,
2. HEAVY METALS IN WWTP
Activated sludge process does not remove
most of the heavy metals efficiently
Heavy metals do not disappear nor react –
they are either in the water or in the
sludge!
Inhibition at high concentrations
More load mainly from the use of
chemicals
5. BIOSORPTION
Biomass can be physically and chemically
treated to increase adsorption.
Mane et. al. used chemically pretreated algal
biomass for SELENIUM removal.
Algae isolates viz. Spyrogyra sp and Nostoc
were treated with NAOH.
Also removes lead and Cadmium upto 60%.
6. FIXED ASP ---- FAST
( Hasani et. Al )
Submerged Fixed media.
Increased surface area/vol ratio.
Provides High Resistance to Shock Loads
Removal efficiencies (Pb,Cr,Ni) increased
with increase in biomass conc.
8. BIOLEACHING
It is the extraction of
metals from SEWAGE
SLUDGE with the help
of bacteria.
Strategy : lower the pH
; increase Fe3+ conc.
Increased removal
efficiencies(Cr,Cu,Zn) ;
reaches max. in 4-10
days time.
Fe+2,S
substrate
A.
FERROOX
-IDANS
Ph
reduction&
metal
solubilization
9. REMOVAL USING EPS
Extracellular polymeric substances produced by
Cloacibacterium normanense with crude glycerol is used.
Ni = 85% ; Al = 72% was removed
Factors affecting rate :
contact time (12Hrs) ; concentration(35 mg/l) ; method of
extraction of EPS (centrifugation)
Good alternative as bioflocculant and low cost
adsorbent.
11. Refrences
http://ascelibrary.org/doi/abs/10.1061/9780784479162.241
[1] Mane P. C, Bhosle A. B, Jangam C. M and Vishwakarma C. V,
“Bioadsorption of Selenium by Pretreated Algal Biomass”, Advances in applied
science research, volume 2, pp-207-211, 2011.
[2] Jianlong Wang, Can Chen, “Biosorbents for heavy metals removal and their
future”, Biotechnology Advances Vol.27, pp195–226, 2009.
Liu, F., Zhou, L., Zhou, J., Song, X., and Wang, D. (2012). "Improvement of
sludge dewaterability and removal of sludge-borne metals by bioleaching at
optimum pH." Journal of Hazardous Materials, 10.1016/j.jhazmat.2012.04.028,
170-177.
Bala subramanian, S., Yan, S., Tyagi, R.D., Surampalli, R.Y., 2010. EPS
producing bacterial strains of municipal ww sludge: isolation, molecular
identification, EPS characterization and performance for sludge settling and
dewatering. Water Res. 44, 2253–2266.
Notes de l'éditeur
They also used live algae for the same treatment and found that chemically treated were more efficient. They used NAOH (CAUTIC SODA) for the treatment and observed more efficient removal. Biomass work in 2 processes –adsorption and fixation.
@ 5mg/l conc. For Pb ,Cr,Ni were 84%,90%,87% respectively ..while @1mg/l 84 75 80.
Fixed media submerged in aeration tank for microbial growth
Process analogous to activated sludge process with increased surface area/vol ratio.
Proven in Thousands of Applications Globally
Stable Process with No Internal Moving Parts
Higher Loading Rates – Smaller Footprint
Provides High Resistance to Shock Loads
Typically No Daily Operation Required (Minimal Overall)
We can see howa fast set up looks like
Bioleaching of heavy metals from sewage sludge has been shown to be a promising technique for sludge decontamination in such a complex matrix. The effect of two types of substrates ( Fe2+Fe2+ and S0S0 ) and their combination on metal removal efficiencies was studied in a batch system using Acidithiobacillus ferrooxidans. The results showed that the inoculation of A. ferrooxidans and coaddition of Fe2+Fe2+ and S0S0 accelerated pH reduction and metal solubilization. After 4–10 days of bioleaching, the following removal efficiencies were obtained: Cr 80%; Cu 100%; and Zn 100%, which were the maximum that have been reported. The time required for Cr to reach the maximum was 10 days, whereas for Cu and Zn the time needed was only 4–6 days. Three different patterns of solubilization for Cr, Cu, and Zn were established as a function of pH and Fe3+Fe3+ concentration. Cr required a threshold pH of around 2.0 to initiate its solubilization, whereas Cu solubilization was controlled simultaneously by pH and Fe3+Fe3+ concentration. The pH appeared to be the sole factor responsible for the solubilization of Zn that was initiated at 4.0–4.5. Fundamental strategy for enhancing metal removal efficiencies is to lower the pH and to sustain high Fe3+Fe3+ concentration, which can be achieved by increasing sulfate concentration, facilitating Fe2+Fe2+ biooxidation, and decreasing the precipitation of jarosite and Read More: http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-025X%282008%2912%3A3%28159%29
Removal capacity study – flask were incubated at 250 rpm and 30 degree c for 12 h and anatomized for metal content.
The highest concentration of EPS was obtained
using EDTA compared to centrifugation or heating method.
However, 11 times higher amount of EDTA extracted EPS was
required to approximately give similar flocculation activity as
given by the EPS extracted by centrifugation method.
High metal removal efficiency was observed using 35mg/L of
B-EPS extracted by centrifugation method.
