Design of UASBR Upflow Anaerobic Sludge Blanket Reactor

 These are the 4 top applications of the UASB reactors:

• Breweries and beverage industry

• Distilleries and fermentation industry

• Food Industry, Slaughter Houses.

• Pulp and paper

Together, these four industrial sectors account for 87% of the applications. However, the applications of the technology are rapidly expanding, including:

1.      treatment of chemical and petrochemical industry effluents

2.      textile industry wastewater

3.      landfill leachates

4.      Conversions in the sulfur cycle and removal of metals.

YOU NEED AN EXPERT WITH SPECIFIC INDUSTRY WISE EXPERIENCE TO DESIGN A PROPER UASBR SYSTEM. DIFFERENT SECTOR OF INDUSTRY REQUIRES SOME MINOR CHANGES IN DATA REQUIRED DURING DESIGN.IT COMES ONLY FROM EXPERIENCE. 

The UASB reactor can be designed as circular or rectangular. Modular design can be preferred when the volume of reactor exceeds about 400 m3. It is necessary to select proper range of operating parameters for design, such as, OLR, SLR, superficial liquid upflow velocity (referred as liquid upflow velocity), and HRT. The literature recommendations for all these parameters and design procedure to account these recommendations are given below.

What is Upflow Anaerobic Sludge Blanket?

Upflow anaerobic sludge blanket, or UASB, is a form of anaerobic (oxygen-free) digester used in wastewater treatment. It is a methane-producing digester which uses an anaerobic process and forming a blanket of granular sludge and is processed by anaerobic microorganism.

UASB was developed in 1970s by Letinga in the Netherlands. It is essentially a suspended growth system in which proper hydraulic retention time (HRT) and organic loading rate (OLR) is maintained in order to facilitate the dense biomass aggregation known as granulation.

How to Design UASB Pond

About a week ago, I asked the appointed vendor who will design and supply wastewater treatment unit about design calculation of UASB pond. The design of UASB pond is a function of:

• COD input of wastewater
• Flow of wastewater
• Organic loading rate
• Hydraulic retention time

Organic loading rate is a measure of the biological conversion capacity of the anaerobic digestionsystem. It is expressed in kg Chemical Oxygen Demand (COD) or Volatile Solids (VS) per cubic meter of reactor. A relatively high organic loading rate facilitated the formation of anaeronic granules in UASB systems.

In general, there are two ways to design an UASB reactor.

1. If input COD is 5000 – 15000 mg/L or more, the design method should be used based on Organic Loading Rate
2. If input COD less than 5000 mg/L, the design method should be based on velocity

Some H2S gas can pass the GSL separator and accumulate above the water level in the top of the reactor. This will be oxidized to sulphate by oxygen in the air to form Sulphuric Acid that will in turn cause corrosion of both concrete and steel. Below the water level: Calcium Oxide, (CaO), in concrete can be dissolve with by Carbon Dioxide, (CO2), in the liquid in low pH conditions. To avoid these problems, the material used to construct the UASB reactor should be corrosion resistant, such as stainless steel or plastics, or be provided with proper surface coatings, (e.g. coated concrete rather than coated steel, plastic covered with impregnated hardwood for the settler, plastic fortified plywood, etc).
Operation
Operation criteria: The optimum pH range is from 6.6 to 7.6 The wastewater temperatures should not be < p =" 350"> 20oC) and sometimes the start-up can take up to 3 – 4 months. In start-up process, hydraulic loading must be Ј 50% of the design hydraulic loading.
The start-up of the UASB reactor can be considered to be complete once a satisfactory performance of the system has been reached at its design load.

Let’s take an example.

Data

Waste water input flow rate (Q) = 62.5 m3/day

COD = 15,000 mg/L = 15 kg/m3

Organic loading rate = 5.5 kg COD/m3.day (I found that organic loading rate is sometimes state of art in wastewater treatment design. Some vendors may have already had the data)

Volume of tank = Q x C /OLR = 62.5 x 15 / 5.5 = 170 m3

Note: the above volume is the actual volume. You need to add more volume (as void volume).

Calculating an UASB Tank Based on Velocity

When input COD < 5,000 mg/l, using the method base on ORL is not effective in operation process because the granular sludge will be hardly formed. Therefore, the design criteria must be:
Up-flow velocity V Ј 0,5 m/h. Hydraulic retention time HRT і 4 h Chosen in table 1, the height of sludge is Hs = 3 – 5 m The height of setting area HSe і 1.2 m The volume of the UASB reactor: W = Q x HRTThe area of the UASB reactor: A = V / Q

GSL Separator Design

Slope of the separator bottom from 45 – 60oFree surface in the aperture between the gas collectors: 15 – 20% of reactor area.Height of separator from 1.5 – 2 m
The baffles to be installed beneath the gas domes should overlap the edge of the domes over a distance from 10 – 20 cm
Construct material: In the anaerobic conditions of an UASB reactor, there is a risk of corrosion in two main situations:
Some H2S gas can pass the GSL separator and accumulate above the water level in the top of the reactor. This will be oxidized to sulphate by oxygen in the air to form Sulphuric Acid that will in turn cause corrosion of both concrete and steel. Below the water level: Calcium Oxide, (CaO), in concrete can be dissolve with by Carbon Dioxide, (CO2), in the liquid in low pH conditions. To avoid these problems, the material used to construct the UASB reactor should be corrosion resistant, such as stainless steel or plastics, or be provided with proper surface coatings, (e.g. coated concrete rather than coated steel, plastic covered with impregnated hardwood for the settler, plastic fortified plywood, etc).

YOU NEED ONE TECHNICAL PERSON WITH EXPERIENCE TO RUN A PROPER UASBR SYSTEM.

Operation & Maintenance (O&M)

Operation criteria: The optimum pH range is from 6.6 to 7.6 The wastewater temperatures should not be < 5 °C because low temperatures can impede the hydrolysis rate of phase 1 and the activity of methanogenic bacteria. Therefore in winter season, methane gas may be needed to heat the wastewater to be treated in the reactor.

Always maintain the ratio of COD : N : P = 350 : 5 : 1 If there is a deficiency of some of these nutrients in the wastewater nutrient addition must be made to sustain the micro-organisms. Chemicals that are frequently used to add nutrients (N, P) are NH4H2PO4, KH2PO4, (NH4)2CO3…

Suspended solid (SS) can affect the anaerobic process in many ways:

Formation of scum layers and foaming due to the presence of insoluble components with floating properties, like fats and lipids. Retarding or even completely obstructing the formation of sludge granules. Entrapment of granular sludge in a layer of adsorbed insoluble matter and sometimes also falling apart (disintegration) of granular sludge. A sudden and almost complete wash-out of the sludge present in reactor Decline of the overall methanogenic activity of the sludge due to accumulation of SS Therefore, the SS concentration in the feed to the reactor should not exceed 500 mg/l In phase 2 and 3 the pH will be reduced and the buffer capacity of wastewater may have to be increased to provide alkalinity of 1000 – 5000 mg/l CaCO3.DESLUDGING PIPES SHOULD BE USED TO MANAGE THE UASB.

Start-up:

 An UASB reactor requires a long time for start-up, e.g. from 2 – 3 weeks in good conditions (t > 20oC) and sometimes the start-up can take up to 3 – 4 months. In start-up process, hydraulic loading must be Ј 50% of the design hydraulic loading.
The start-up of the UASB reactor can be considered to be complete once a satisfactory performance of the system has been reached at its design load.

UASB Units

UASB type units are one in which no special media have to be used since the sludge granules themselves act as the 'media' and stay in suspension. UASB system is not patented. A typical arrangement of a UASB type treatment plant for municipal sewage would be as follows:

1. Initial pumping
2. Screening and degritting
3. Main UASB reactor
4. Gas collection and conversion or conveyance
5. Sludge drying bed
6. Post treatment facility

In the UASB process, the whole waste is passed through the anaerobic reactor in an upflow mode, with a hydraulic retention time (HRT) of only about 8-10 hours at average flow. No prior sedimentation is required. The anaerobic unit does not need to be filled with stones or any other media; the upflowing sewage itself forms millions of small "granules" or particles of sludge which are held in suspension and provide a large surface area on which organic matter can attach and undergo biodegradation. A high solid retention time (SRT) of 30-50 or more days occurs within the unit. No mixers or aerators are required. The gas produced can be collected and used if desired. Anaerobic systems function satisfactorily when temperatures inside the reactor are above 18-20°C. Excess sludge is removed from time to time through a separate pipe and sent to a simple sand bed for drying.

Design Approach

Size of Reactor: Generally, UASBs are considered where temperature in the reactors will be above 20°C. At equilibrium condition, sludge withdrawn has to be equal to sludge produced daily. The sludge produced daily depends on the characteristics of the raw wastewater since it is the sum total of (i) the new VSS produced as a result of BOD removal, the yield coefficient being assumed as 0.1 g VSS/ g BOD removed, (ii) the non-degradable residue of the VSS coming in the inflow assuming 40% of the VSS are degraded and residue is 60%, and (iii) Ash received in the inflow, namely TSS-VSS mg/l. Thus, at steady state conditions,

SRT= Total sludge present in reactor, kg          Sludge withdrawn per day, kg/d

     = 30 to 50 days.

Another parameter is HRT which is given by:

HRT= Reactor volume, m³ 
         Flow rate, m³/h

     = 8 to 10 h or more at average flow.

The reactor volume has to be so chosen that the desired SRT value is achieved. This is done by solving for HRT from SRT equation assuming (i) depth of reactor (ii) the effective depth of the sludge blanket, and (iii) the average concentration of sludge in the blanket (70 kg/m³). The full depth of the reactor for treating low BOD municipal sewage is often 4.5 to 5.0 m of which the sludge blanket itself may be 2.0 to 2.5 m depth. For high BOD wastes, the depth of both the sludge blanket and the reactor may have to be increased so that the organic loading on solids may be kept within the prescribed range.

Once the size of the reactor is fixed, the upflow velocity can be determined from

Upflow velocity m/h = Reactor height
                                     HRT, h

Using average flow rate one gets the average HRT while the peak flow rate gives the minimum HRT at which minimum exposure to treatment occurs. In order to retain any flocculent sludge in reactor at all times, experience has shown that the upflow velocity should not be more than 0.5 m/h at average flow and not more than 1.2 m/h at peak flow. At higher velocities, carry over of solids might occur and effluent quality may be deteriorated. The feed inlet system is next designed so that the required length and width of the UASB reactor are determined.

The settling compartment is formed by the sloping hoods for gas collection. The depth of the compartment is 2.0 to 2.5 m and the surface overflow rate kept at 20 to 28 m³/m²-day (1 to 1.2 m/h) at peak flow. The flow velocity through the aperture connecting the reaction zone with the settling compartment is limited to not more than 5 m/h at peak flow. Due attention has to be paid to the geometry of the unit and to its hydraulics to ensure proper working of the "Gas-Liquid-Solid-Separator (GLSS)" the gas collection hood, the incoming flow distribution to get spatial uniformity and the outflowing effluent.

Physical Parameters

A single module can handle 10 to 15 MLD of sewage. For large flows a number of modules could be provided. Some physical details of a typical UASB reactor module are given below:

Reactor configuration	Rectangular or circular. Rectangular shape is preferred
Depth	4.5 to 5.0 m for sewage.
Width or diameter	To limit lengths of inlet laterals to around 10-12 m for facilitating uniform flow distribution and sludge withdrawal.
Length	As necessary.
Inlet feed	gravity feed from top (preferred for municipal sewage) or pumped feed from bottom through manifold and laterals (preferred in case of soluble industrial wastewaters).
Sludge blanket depth	2 to 2.5 m for sewage. More depth is needed for stronger wastes.
Deflector/GLSS	This is a deflector beam which together with the gas hood (slope 60) forms a "gas-liquid-solid-separator" (GLSS) letting the gas go to the gas collection channel at top, while the liquid rises into the settler compartment and the sludge solids fall back into the sludge compartment. The flow velocity through the aperture connecting the reaction zone with the settling compartmentt is generally limited to about 5m/h at peak flow.
Settler compartment	2.0-2.5 m in depth. Surface overflow rate equals 20-28 m3/m2/d at peak flow.

Process Design Parameters

A few process design parameters for UASBs are listed below for municipal sewages with BOD about 200-300 mg/l and temperatures above 20°C.

HRT	8-10 hours at average flow (minimum 4 hours at peak flow)
SRT	30-50 days or more
Sludge blanket concentration (average)	15-30 kg VSS per m3. About 70 kg TSS per m3.
Organic loading on sludge blanket	0.3-1.0 kg COD/kg VSS day (even upto 10 kg COD/ kg VSS day for agro-industrial wastes).
Volumetric organic loading	1-3 kg COD/m3 day for domestic sewage (10-15 kg COD/m3 day for agro-industrial wastes)
BOD/COD removal efficiency	Sewage 75-85% for BOD. 74-78% for COD.
Inlet points	Minimum 1 point per 3.7-4.0 m2 floor area.
Flow regime	Either constant rate for pumped inflows or typically fluctuating flows for gravity systems.
Upflow velocity	About 0.5 m/h at average flow, or 1.2 m/h at peak flow, whichever is low.
Sludge production	0.15-0.25 kg TS per m3 sewage treated.
Sludge drying time	Seven days (in India)
Gas production	Theoretical 0.38 m3/kg COD removed. Actual 0.1-0.3 m3per kg COD removed.
Gas utilization	Method of use is optional. 1 m3 biogas with 75% methane content is equivalent to 1.4 kWh electricity.
Nutrients nitrogen and phosphorus removal	5 to 10% only.

HOW TO DESIGN BIO GAS HOLDER
GAS PRODUCTION & POWER GENERATION:

The gas flowing upward with the liquid will be prevented from escaping with the treated flow by GLSS and beam deflector, which will divert it to the gas collector domes. The gas produced shall be passed through 100 mm dia FRP pipe for individual domes and collected at a common point for each reactor by a common header of 200 mm dia pipe from where it will conveyed to the gas holder for constant flow to the gasomete generator or flaring in open atmosphere at about 6 meter above ground level.

Quantity of Gas Production:

PARAMETER	INLET OF UASB	OUTLET OF UASB	REMOVAL IN UASB
BOD	1700 ppm	340 ppm	80%
COD	3300 ppm	1320 ppm	60%
TSS	1800 ppm	450 ppm	75%

FLOW IN UASB = 1500 KLD (Taking full future capacity into account)

Influent COD@ 3300 ppm = 4950 Kg

Effluent COD = 1980 Kg

COD removed in a day = 2970 kg

Bio gas produced @ 0.1 cu mtr per kg of COD removed = 297 cu mtr per day.

Capacity of gas holder:

The primary purpose of a gas holder is to adjust the difference in the rate of gas production and consumption. As bio gas enters or leaves, the holder rises or falls  by guide rails.

Provide a gas holder of 300 cu mtr capacity.

POWER GENERATION:

The bio gas produced in UASB process should be utilized for production of electric power. The amount of electric power generated shall be as under:

Bio Gas production = 297 cu mtr /day

Methane content (65.75%) = 195.28 cu mtr

Calorific value =28.9 MJ/N.cu mtr

Energy content 195.28x28.9x273/(273+30)=5048 MJ/Day

Generator efficiency--- 30%

Electricity generated =0.3x5048x1000000/3600x1000

                                      = 420.66

Electric power generated = 420.66x0.04167=17.5289 kw  say17 kw 

                                     = 1.25x 17= 21.25 kva.

We can go for a gas engine of capacity 10 KW . If any gas is left , it will be flared or supplied to staff quarters.

NOTE: A 56 mld UASB plant having  Inlet COD =400 ppm can safely run a 45 KW gas engine.

   REFERENCE BOOK FOR DESIGN

1. Given influent data

Flow to UASB
500 KLD continuous over 24 hours

Convert to cubic meters per day
Q = 500 m3 per day

Hourly flow
Qh = 500 divided by 24 = 20.8 m3 per hour

Influent characteristics
pH 8.4
TSS 1500 mg per L
BOD 2000 mg per L
COD 4000 mg per L
Oil and grease 100 mg per L

This is typical high strength slaughterhouse wastewater and suitable for UASB after basic pretreatment.

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2. Key design criteria from Metcalf and Eddy and Indian UASB practice

For slaughterhouse wastewater, accepted design ranges are

Organic loading rate
5 to 10 kg COD per m3 per day

Hydraulic retention time
6 to 10 hours

Upflow velocity
0.5 to 1.0 m per hour

Target COD removal
60 to 70 percent

We will design conservatively to avoid biomass washout.

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3. Organic load calculation

Influent COD concentration
4000 mg per L = 4 kg per m3

Daily COD load
= Flow × COD
= 500 × 4
= 2000 kg COD per day

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4. Reactor volume based on organic loading

Select design organic loading rate
= 6 kg COD per m3 per day

Required UASB volume
= COD load divided by OLR
= 2000 divided by 6
= 333 m3

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5. Check hydraulic retention time

HRT = Reactor volume divided by flow

= 333 divided by 500
= 0.666 day
= 16 hours

This is higher than the minimum recommended value and is good for slaughterhouse wastewater with fats and proteins.

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6. Reactor geometry selection

Assume cylindrical reactor for uniform flow.

Assume liquid depth
= 6.0 m
This is standard in Indian UASB designs.

Required cross sectional area
= Volume divided by depth
= 333 divided by 6
= 55.5 m2

Diameter of reactor
Area = pi × D squared divided by 4

D squared = 4 × 55.5 divided by pi
D squared = 70.7
D = 8.4 m

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7. Upflow velocity check

Upflow velocity
= Flow per hour divided by area

Flow per hour
= 20.8 m3 per hour

Upflow velocity
= 20.8 divided by 55.5
= 0.37 m per hour

This is within safe limits and minimizes sludge washout.

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8. Sludge blanket considerations

Design sludge blanket height
= 40 to 50 percent of reactor depth

Adopt
= 2.5 to 3.0 m sludge blanket

Granular sludge concentration typically
20 to 30 g VSS per L

This volume is sufficient for stable digestion of slaughterhouse organics.

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9. Gas production estimate

Assume COD removal
= 65 percent

COD removed
= 2000 × 0.65
= 1300 kg per day

Methane yield
= 0.35 m3 CH4 per kg COD removed

Daily methane production
= 1300 × 0.35
= 455 m3 CH4 per day

Biogas including CO2
≈ 600 to 650 m3 per day

This is enough for boiler or hot water use in the slaughterhouse.

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10. Oil and grease impact and pretreatment note

Oil and grease at 100 mg per L is acceptable only if

A grease trap or DAF is provided before UASB
TSS is reduced to below 800 mg per L

Without pretreatment, granule flotation and scum formation will occur.

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11. Expected UASB effluent quality

COD removal 60 to 70 percent
Expected outlet COD
1200 to 1600 mg per L

BOD removal 65 to 75 percent
Expected outlet BOD
500 to 700 mg per L

Post treatment like MBBR or SBR is mandatory for reuse compliance in India.

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12. Final UASB design summary

Flow
500 KLD

Reactor volume
333 m3

Reactor type
Single cylindrical UASB

Diameter
8.4 m

Liquid depth
6.0 m

Hydraulic retention time
16 hours

Upflow velocity
0.37 m per hour

Organic loading rate
6 kg COD per m3 per day

Estimated biogas
600 to 650 m3 per day

PART A

INLET DISTRIBUTION SYSTEM DESIGN

The goal is uniform upward flow across the entire reactor area so the sludge blanket remains stable and no dead zones form.

1. Design basis

Total flow
500 m3 per day
= 20.8 m3 per hour

Reactor internal diameter
8.4 m

Reactor cross sectional area
55.5 m2

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2. Number of inlet points

Metcalf and Eddy recommendation
1 inlet per 3 to 5 m2 of reactor area for high strength wastewater

Adopt conservative value
1 inlet per 4 m2

Required number of inlet points
= 55.5 divided by 4
= 13.9

Adopt
16 inlet points

This gives excellent flow distribution for slaughterhouse wastewater.

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3. Flow per inlet

Total hourly flow
20.8 m3 per hour

Flow per inlet
= 20.8 divided by 16
= 1.30 m3 per hour

Convert to liters per second
= 1.30 divided by 3.6
= 0.36 L per second

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4. Inlet pipe sizing

Recommended inlet velocity
0.6 to 1.0 m per second
Select
0.75 m per second

Pipe area required
Q divided by velocity
= 0.00036 divided by 0.75
= 0.00048 m2

Equivalent pipe diameter
≈ 25 mm

Adopt
32 mm internal diameter for clog free operation

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5. Inlet layout

One central feed header pipe
Diameter 200 mm

Radial distribution arms
4 arms at 90 degrees

Each arm serves
4 inlet risers

Inlet nozzles placed uniformly across the floor
Clear spacing between nozzles
≈ 1.8 to 2.0 m

Each inlet riser ends 150 to 200 mm above reactor bottom with downward facing nozzle to avoid sludge ingress.

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PART B

GLS SEPARATOR DESIGN
Gas Liquid Solid separator is the heart of the UASB.

---

6. Design criteria

Upward liquid velocity at GLS zone
less than 0.6 m per hour

Gas collection efficiency
greater than 90 percent

Inclination of deflector baffles
45 to 60 degrees

---

7. GLS surface area

GLS projected area is normally
25 to 35 percent of reactor cross sectional area

Adopt
30 percent

GLS area
= 0.30 × 55.5
= 16.7 m2

---

8. Number of GLS modules

For an 8.4 m diameter reactor
Use 4 identical GLS modules

Area per module
= 16.7 divided by 4
= 4.2 m2

Each module roughly
2.1 m × 2.0 m footprint

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9. GLS vertical arrangement

Bottom of gas hood
= 3.0 m above reactor floor

Top of gas hood
= 4.8 m above reactor floor

Gas collection zone height
≈ 1.8 m

Settling zone above GLS
≈ 1.0 to 1.2 m

Clear liquid zone below effluent weir
≈ 0.8 m

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10. Effluent launders

Peripheral launder channel provided at reactor wall

Weir loading rate
< 250 m3 per meter per day

Required weir length
= 500 divided by 250
= 2.0 m

Available circumference
= pi × 8.4
= 26.4 m

Hence weir loading is extremely safe.

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PART C

GAS DOME DESIGN

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11. Biogas production basis

Earlier calculated biogas
≈ 600 to 650 m3 per day

Hourly biogas generation
= 650 divided by 24
≈ 27 m3 per hour

---

12. Gas dome volume

Recommended gas storage
20 to 30 percent of daily gas production

Adopt
25 percent

Gas storage volume
= 0.25 × 650
= 160 m3

---

13. Gas dome geometry

Use fixed concrete dome integrated above GLS

Assume dome height
2.5 m

Required dome plan area
= Volume divided by height
= 160 divided by 2.5
= 64 m2

This matches well with reactor top area.

Dome diameter
≈ 9.0 m

Provide minimum freeboard
0.5 m above maximum gas level

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PART D

BIOGAS PIPING DESIGN

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14. Main gas header pipe

Peak gas flow
27 m3 per hour
= 0.0075 m3 per second

Recommended gas velocity
8 to 12 m per second

Select
10 m per second

Pipe area
= 0.0075 divided by 10
= 0.00075 m2

Equivalent diameter
≈ 31 mm

Adopt
50 mm diameter GI or HDPE gas pipe to avoid pressure losses and condensation blockage

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15. Gas safety and accessories

Mandatory fittings

Water seal trap
Flame arrestor
Pressure relief valve
Condensate drain at lowest point
Non return valve

Design gas pressure
10 to 20 cm water column

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PART E

FINAL DESIGN SUMMARY

Inlet points
16 numbers

Inlet riser diameter
32 mm

Main inlet header
200 mm

GLS modules
4 numbers

GLS total area
16.7 m2

Gas dome volume
160 m3

Main gas pipe
50 mm

Expected gas pressure
low pressure biogas system

HEIGHT DESCRIPTION

From bottom to top:

1. Reactor shell

• Internal diameter: 8.4 m

• Liquid depth: 6.0 m

• Cylindrical RCC structure

2. Inlet zone

• Inlet distribution pipes shown at the bottom

• Actual inlet risers are placed about 150 to 200 mm above floor level

• Flow is upward through the sludge blanket

3. Sludge blanket zone

• Height: 3.0 m

• Active anaerobic digestion zone

• Granular sludge retained here

4. GLS separator zone

• Height: 1.8 m

• Located from 3.0 m to 4.8 m above reactor floor

• Gas hoods deflect biogas

• Solids slide back to sludge blanket

• Liquid moves upward

5. Settling zone

• Height: 1.0 m

• From 4.8 m to 5.8 m

• Allows fine solids to settle back

6. Effluent launder

• Located just below liquid level

• Peripheral launder with V notch or serrated weir

• Leads to post treatment unit

7. Gas dome

• Dome height: 2.5 m

• Integrated RCC gas dome

• Collects biogas from GLS

• Connected to gas piping with condensate trap and safety devices

                           

Expected UASB effluent quality

COD removal 60 to 70 percent
Expected outlet COD
1200 to 1600 mg per L

BOD removal 65 to 75 percent
Expected outlet BOD
500 to 700 mg per L

Post treatment like MBBR or SBR is mandatory for reuse compliance in India.

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MBBR 1 (50% fill)
Reactor volume 167 m3
Media volume 83 m3
Dimensions 9.8 × 3.9 × 4.5 m
HRT 8.0 hours

Clarifier 1
Diameter 5.0 m
Depth 4.0 m

MBBR 2 (50% fill)
Reactor volume 146 m3
Media volume 73 m3
Dimensions 9.0 × 3.6 × 4.5 m
HRT 7.0 hours

Clarifier 2
Diameter 5.6 m
Depth 4.0 m

Total aerobic HRT after UASB
≈ 15 hours

EXPECTED FINAL PERFORMANCE

After Clarifier 2:

BOD
< 20 mg per L

COD
< 150 mg per L

TSS
< 10 mg per L

Suitable for filtration and disinfection for reuse.

Process Efficiency Chart (Summary)

Stage	Effluent BOD (mg/L)	Effluent COD	TSS/FOG
Influent	2000	5000	2000/1000
After O&G Trap	~1800	~4800	1800/300
After DAF	~1200	~3500	500/150
After UASB	~500	~1500	300/100
After MBBR1	~250	~800	100/50
After MBBR2	~100	~400	50/20
After Filters	<50	<200	<10
Reuse	Typically <30	<100	<5

ZLD will further polish via evaporation.

                                        INDIAN STANDARDS

ENVO PROJECT"S FIRST UASBR PROJECT WAS IN 2005. SOME OF OUR PROJECT PHOTOS

VIDEO OF THE PLANT

Read on http://www.slideshare.net/nitinyadav16/anaerobic-treatment-of-industrail-wastewater

Source: http://nptel.ac.in/courses/105104102/Lecture%2032.htm