Wastewaster treatment and waste gas treatment has been explained in this presentation

1. Biomethanation and energy recovery,
Bioscrubbers, Biofilters
V.Sundaralakshmi
2014027036

2. BIOMETHANATION
Biomethanation is the process of conversion of organic matter in the waste (liquid or solid) to biogas and
manure by microbial action in the absence of air.
 Methanogens (Archaebacteria) are obligate anaerobes which produce CH4 by reducing acetate and/or CO2.
 Methanogens are widely used in anaerobic digestors to treat wastewater as well as aqueous organic pollutants.
Industries have selected methanogens for their ability to perform biomethanation during wastewater
decomposition. An example is the members of Methanosaeta genus dominate the digestion of palm oil mill
effluent (POME) and brewery waste.
 Anaerobic decomposition of waste materials produces large amounts of methane. Many sewage treatment plants
produce this fuel.
 Biogas, a mixture of different gases is produced by anaerobic microbes using domestic and agricultural wastes.
 Bulk (about 50 – 70%) of biogas is methane (CH4) and other gases are in low proportions. These include CO2 (25
– 35%), H2 (1 – 5%), N2 (2 – 7%) and O2 (0 – 0.1%).
 Interest in biomethanation as an energy-saving waste treatment has led to the development of a range of anaerobic
reactor designs.

3. BIOMETHANATION
• Anaerobic digestion is a technologically
simple process, with a low energy
requirement, used to convert organic material
from a wide range of wastewater types, solid
wastes and biomass into methane.
• The methanogenic activity occurs at 55˚C or
higher.
• pH – neutral (6.5-7.5).

4. ANAEROBIC DIGESTION
SYSTEMS
HIGH RATE ANAEROBIC REACTORS
1.Biomass retention.
2.High SRT and low HRT.
3.Used in treatment of waste wasters.
LOW RATE ANAEROBIC REACTORS
1. Usually very low or no biomass
retention.
2. High HRT.
3. Used in treatment of solid wastes

5. Anaerobic digestion is used as source of renewable energy since
the process produce biogas. Biogas can be directly used as a fuel
or can be upgraded to natural gas quality biomethane.

6. HIGH-RATE ANAEROBIC REACTORS FOR
WASTEWATER TREATMENT
1. Anaerobic Contact Reactor(AC).
2. Upflow Anaerobic Sludge Blanket Reactor(UASB).
3. Anaerobic Filter Reactor(AF).
4. Anaerobic Fluidized And Expanded Bed Systems.

7. ANAEROBIC CONTACT REACTOR
 The anaerobic contact process (ACP) was
developed in 1950s and was first high rate
anaerobic treatment system.
 Produce methane but methane collection
increases operational problems.

8. UPFLOW ANAEROBIC SLUDGE BLANKET
REACTOR(UASB).
1. The Upflow Anaerobic Sludge Blanket (UASB)
reactor was developed in 1970 at Wageningen
University, Netherlands.
2. This is one of the most remarkable and
significant developments in high-rate anaerobic
treatment technology.
3. Organic loading in the range of 1-20 kg COD
/m3.d can be applied with removal efficiency of
75 to 85 % and HRT of 4 to 24 h.

9. ANAEROBIC FILTER REACTOR
1. The anaerobic filter (AF) (Hamilton 2012) are also known
as the fixed film digester or packed bed digester.
2. The AF system will remain attractive for treatment of
mainly soluble types of wastewaters, particularly when the
sludge granulation process cannot occur satisfactory.
3. The major disadvantage of the AF concept is the difficulty
to maintain the required contact between sludge and
wastewater, because clogging of the “bed” easily occurs.
4. High loading rates up to 10 kg COD m−3 day−1.

10. ANAEROBIC FULIDIZED AND EXPANDED BED
SYSTEMS
1. The fluidized bed (FB) system IS an advanced anaerobic technology which may
reach loading rates exceeding 40 kg COD m−3 day−1, when operated under defined
conditions.
2. The FB process is based on the occurrence of bacterial attachment to non-fixed or
mobile carrier particles, which consist, of fine sand, basalt, pumice, or plastic
3. FB reactors are very efficient due to following reasons:
• Good mass transfer resulting from liquid turbulence and high flow rate around the
particles
• Less short circuiting and less clogging due to the occurrence of large pores
Through bed expansion
• High specific surface area of the carriers make FB reactors highly efficient

11. Biofilters
BIOFILTERS:
• Biofilter is one of the most important separation processes that can be employed to remove organic
• pollutants from air, water, and wastewater
• Bio filtration is a pollution control technique using a bioreactor containing living material to capture
and biologically degrade pollutants. Its common use include processing of waste water.
• Biofilters have become the most popular biological treatment technology for odor emissions
emanating from waste water treatment plant because of their simplicity and low construction and
operating costs.

12. PROCESS INVOLVED:
 In a biofiltration system, the pollutants are removed due to biological degradation rather than physical straining as is the
case in normal filter.
 With the progression of filtration process, microorganisms(aerobic, anaerobic, and facultative bacteria; fungi; algae; and
protozoa) are gradually developed on the surface of the filter media and form a biological film or slime layer known as
biofilm.
 The development of biofilm may take few days or months depending on the influent organic concentration.
 The crucial point for the successful operation of a biofilter is to control and maintain a healthy biomass on the surface of
the filter. Since the performance of the biofilter largely depends on the microbial activities, a constant source of
substrates (organic substance and nutrients) is required for its consistent and effective operation.
 There are three main biological processes that can occur in a biofilter,
(i) attachment of microorganism,
(ii) growth of microorganism
(iii) decay and detachment of microorganisms.

13.  Biofilter performance is highly dependent on the nature of the carrier material, also called filter bed.
 The carrier material is a solid phase on which adhesion of biocatalyst(microorganisms) takes place
resulting in the development of a so called biofilm growing as a result of pollutant degradation.

14. Bio-trickling filters
 Bio-trickling filters work in a similar manner to
biofilters, except that an aqueous phase is trickled
over the packing.
 The trickling solution contains essential inorganic
nutrients such as nitrogen, phosphorous, potassium,
etc. and is usually recycled.
 Bio-trickling filters are more complex than biofilters
but are usually more effective, especially for the
treatment of compounds difficult to degrade or
compounds that generate acidic byproducts, such as
H2S

15. PRINCIPLE OF BIO-TRICKLING FILTERS

16. BIO SCRUBBERS
• Bioscrubbers for waste gas treatment are characterized by a physica1 separation of absorption of
volatile compounds into water and subsequent biological treatment of the water in two unit operations.
Bio scrubbing process: Two units.
First part:
A scrubber is used to absorb soluble waste gases into water.
Second part:
Occurs in a basin unit where waste compounds are biological oxidized.

17. BIOSCRUBBER

18. The advantages of bioscrubbers compared to biofilters are:
• Smaller volume of the equipment;
• Better pH control;
• No clogging problems of packing materials;
• Lower occurrence of toxic concentrations in the water phase.
Disadvantages:
• Only cost-effective for pollutants with a dimensionless Henry's law's coefficient below 0.01;
• More difficult to attain elimination efficiencies higher than 98%;
• More complicated start-up procedure;
• Higher operational costs.