Environmental Engineer at Envo Projects,Delhi,India.www.envoprojects.com I am collecting Articles i found interesting here so that i can read them at my leisure later on.This blog is for my own self improvement.TO AVOID COPYRIGHT VIOLATIONS, ALL POSTS ARE SHOWN ALONG WITH SOURCES FROM WHERE ITS TAKEN.PLEASE CONTACT ME IF YOU ARE THE AUTHOR AND YOUR NAME IS NOT DISPLAYED IN THE ARTICLE. +918076071358(WHATSAPP)
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I HAVE SHARED ALL MY PRACTICAL WATER TREATMENT EXPERIENCES WITH SOLVED EXAMPLE HERE SO THAT ANYBODY CAN USE IT.
SEARCH THIS BLOG BELOW FOR ENVO ,COMPACT STP,ETP,STP,FMR,MBBR,SAFF,IRON,ARSENIC,FLUORIDE,FILTER,RO,UASB,BIO GAS,AERATION TANK,SETTLING TANK,DOSING,AMC.
PRICE LIST OF COMPACT STP (SEWAGE TREATMENT PLANT)
Capacity
Ex Delhi Cost
5 kld
Please contact for price
10 kld
25 kld
30 kld
50 kld
100 kld
Note:
1.Variation
from our standard make or standard
design
will vary the cost mentioned.
2.All
Taxes Extra as applicable
3.All
Transportation charges extra as actual.
An introduction to MBBR (moving bed biofilm reactor )/ FM Reactor/ FAB /FMR Reactor wastewater treatment
When communities of microorganisms grow on surfaces, they are called biofilms. Microorganisms in a biofilm wastewater treatment process are more resilient to process disturbances compared to other types of biological treatment processes. Thus, biofilm wastewater treatment technologies can be considerably more robust especially when compared to conventional technologies like activated suldge process..
In the MBBR biofilm technology the biofilm grows protected within engineered plastic carriers, which are carefully designed with high internal surface area. These biofilm carriers are suspended and thoroughly mixed throughout the water phase. With this technology it is possible to handle extremely high loading conditions without any problems of clogging, and treat industrial and municipal wastewater on a relatively small footprint.
System description
The MBBR biofilm technology is based on specially designed plastic biofilm carriers orbiocarriersthat are suspended and in continuous movement within a tank orreactorof specified volume. The design of associated aerators, grids, sieves, spray nozzles and other integral parts to the reactor is also of great importance in making up the system as a whole .
The industrial and municipal wastewater is led to the MBBR treatment reactor where biofilm, growing within the internal structures of the biocarriers, degrade the pollutants. These pollutants that need to be removed in order to treat the wastewater are food orsubstratefor growth of the biofilm. The biocarrier design is critical due to requirements for good mass transfer ofsubstrateand oxygen to the microorganisms . Excess biofilm sloughs off the biocarrier in a natural way .
An aeration grid located at the bottom of the reactor supplies oxygen to the biofilm along with the mixing energy required to keep the biocarriers suspended and completely mix within the reactor.
Treated water flows from reactor through a grid or a sieve, which retains the MBBR biocarriers in the reactor. Depending on the wastewater, the reactors are may be equipped with special spray nozzles that prevent excessive foam formation.
The MBBR is a biological aerobic degradation of organic pollutants. The process utilizes millions of tiny, polyethylene biofilm elements that provide a high surface area as a home for a vast, highly active bacteria culture. This fixed film process features a flexible reactor design, the ability to handle load increases without the need for extra tankage, and remains stable under large load variations, including temperature, strength or pH. Like the activated sludge process, the MBBR process utilizes the whole volume of an open tank. Unlike an activated sludge reactor,it does not require sludge return to operate effectively. In MBBR , addition of media quantity and Air Quantity is the Key Factor.
Total reactor volume of the MBBRs is designed for different hydraulic retention time for different types of waste water at average flows and than checked against peak flows. Essentially nutrient levels and DO levels are the only control points for the system.
Moving Bed Biofilm Bioreactor (MBBR) process uses the whole tank volume for biomass growth. It uses simple floating media, which are carriers for attached growth of biofilms. Biofilm carrier movement is caused by the agitation of air bubbles. This compact treatment system is effective in removal of BOD as well as nitrogen and phosphorus while facilitating effective solids separation.
Design and Construction Principles
Neutralised and settled wastewater passes through MBBR for reduction in BOD/COD. Most of the MBBR plants are provided with vertically or horizontally mounted rectangular mesh sieves or cylindrical bar sieves. Biofilm carriers are made up of high density (0.95 g/cm3) polyethelene. These are normally shaped as small cylinders with a cross inside and fins outside. The standard filling of carrier is not more than 465 m2/m3. Generally, design load for COD-BOD removal is 20 g COD / m2d. Smaller carriers need smaller reactor volume at a given loading rate (as g/m2d) when the carrier filling is same.
It is advisable to use MBBR in combination with a DEWATS as a pre-treatment unit, depending on the local conditions and input characteristics. It is a very robust and compact alternative for secondary treatment of municipal wastewater, having removal efficiency for BOD 90 – 95% (low rate) and that of 75 – 80% for high rate. Average nitrogen removal is about 85%. There is no need for sludge recirculation. Phosphorus and faecal coliform reduction is feasible with additional passive (non-mechanical) or active (mechanical) system components.
A constantly operating MBBR does not require backwashing or return sludge flows. It has minimal head-loss. Coarse-bubble aeration in the aeration zone in the wastewater treatment tank provides ease of operation at low-cost. Agitation continuously moves the carrier elements over the surface of the screen thus preventing clogging. Maintenance of MBBR system includes screening, influent equalisation, clarifier system, sludge handling and integrated control system. There is no need to maintain f/M ratio as there is self-maintenance of an optimum level of productive biofilm. Skilled labour is required for routine monitoring and operations of pumps and blowers.
DEWATS stands for “Decentralized Wastewater Treatment Systems”.
In the
DEWATS, the waste water/sewage is let through a multi stage low maintenance
system to treat it and recycle it for flushing, gardening and other non potable
end uses.
DEWATS--- modified
septic tank system can be adapted very easilly with the size he is building and
please use bacterial culture from one another septic tank for faster start
up.
He has browsed the net and uses the term
Aerobic, Anaerobic, bacteria
culture, etc. He has also enquired with some suppliers for a solution.
He has read an article 3-4 months back in a
magazine about the use
of Bacterial Culture (solution) to completely digest the solid waste in
the septic tanks.
Provides treatment for domestic and industrial wastewater
Low initial investment costs as no imported materials or components are needed
Efficient treatment for daily wastewater flows of up to 1000m3
Modular design of all components
Tolerant towards inflow fluctuations
Reliable and long-lasting construction design
Low maintenance costs
Hence
DEWATS technology is an effective, efficient and affordable wastewater treatment solution for small and medium sized enterprises (SME).Apartments,Resorts,Restaurants etc
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
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. 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.
If input COD is 5000 – 15000 mg/L or more, the design method should be used based on Organic Loading Rate
If input COD less than 5000 mg/L, the design method should be based on velocity
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 Ñ– 4 h Chosen in table 1, the height of sludge is Hs = 3 – 5 m The height of setting area HSe Ñ– 1.2 m The volume of the UASB reactor: W = Q x HRTThe area of the UASB reactor: A = V / Q
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
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 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:
Initial pumping
Screening and degritting
Main UASB reactor
Gas collection and conversion or conveyance
Sludge drying bed
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. INDIAN STANDARDS
ENVO PROJECT"S FIRST UASBR PROJECT WAS IN 2005. SOME OF OUR PROJECT PHOTOS
Environmental Entrepreneur,Green Biz.NRN Murthy of Infosys says that we Indians are weak in execution.We need to realize the need and practice of gud project management. Form a group of competent Managers,Give them responsibilities and review the project from day One.