Our Product & Services
What We Provide....
Anaerobic digestion (AD) is a treatment for wastewater in the absence of oxygen, producing biogas that can be used to generate electricity and heat. Wastewater treatment using anaerobic process is a very promising technology, which presents extremely interesting advantage compared to the classical aerobic treatment. Green & Smart Sdn Bhd has started doing anaerobic treatment since 1972 and tank digesters from 1984 and built many types of anaerobic treatment system (like UASB, complete mix, contact type, etc) successfully, as turnkey contractors.
For palm oil mill effluent, Green & Smart Sdn Bhd has developed POME-MAS™(Palm Oil Mill Effluent-Mesophilic Anaerobic System) technology, which is different from existing technologies. This will give higher COD reduction efficiency and higher yield of biogas.
Ahead of the competition, G & S is continuously conducting research on the anaerobic treatment.
We will take the Palm Oil Mill Effluent (POME) after the last cooling pond. After removing most of the fiber and broken nuts, it will be pumped to a holding tank where it is well homogenized. Then, the effluent will be pumped into closed anaerobic reactor tanks.
The enclosed anaerobic reactor will operate under mesophilic condition at 30°C-40°C under fully mixed condition. The overflow from digester will go to a settling tank. The supernatant will go to aeration ponds for further treatments. The settled sludge will be recycled to the digesters or send to sludge drying bed.
The biogas from the top of the reactors will go to an automatic CDM compliant closed flare (GREEN-FLARE™). Here all methane must be destroyed before going out of flare chimney; the exhaust temperature maintained above 550°C always.
FEATURES OF OUR SYSTEM:
With our 26 years of anaerobic digestion with 30 over reactors in many countries, we have managed to develop POME-MAS™ specifically for palm oil mill effluent (POME). At present, there are 12 reactors running in FELDA mills. They are of various sizes ranging from 1500 cubic meter to 5000 cubic meter. They are running satisfactorily since 2009. The COD reduction efficiency is from 89% to 95% as can be seen in client’s Acceptance Test Letter. Client tested each rector with its design hydraulic capacity for 24 hours for 12 continuous days. The test were carried out by client and certified by them. Unusual shock loads were sustained well and reactors recovered quickly. We believe we can achieve consistent COD reduction efficiency above 92% (BOD reduction 95% to 97%) with proper supervision and operation.
Gas production is consistent and methane (CH₄) content varies between 60%-75%. Sample tests of H2S shows values between 600ppm to 1000 ppm at flare inlet.
The higher the COD reduction efficiency, higher will be the gas production. This will give higher power production and more revenue.
OUR CREDENTIALS ON BIOGAS PROJECTS
We have commissioned more than 30 anaerobic reactors since 1984 until now, out of that, 12 are for POME. We also have different types of wastewater treatment plants. Our digesters are supplying gas to boilers consistently at Carlsberg Brewery, Shah Alam; Mohan Brewery, India and Heveafil, Batang Kali for more than 10 years, where they are connected to dual fuel burners. Biogas can be used as fuel for gas engine to generate power.
- COD reduction efficiency of POME-MAS™ reactors 2, 3 and 4 for Palm Oil Mill 1 on July 2009
- COD reduction efficiency of POME-MAS™ reactor 1 for Palm Oil Mill 2 on November 2010
- COD reduction efficiency of POME-MAS™ reactor for Palm Oil Mill 4 on June 2009.
- COD reduction efficiency of POME-MAS™ reactor 2 for Palm Oil Mil 2 on December 2010
- COD reduction efficiency of POME-MAS™ reactor 1 for Palm Oil Mill 3 on May and Jun 2010
Most conventional wastewater processes for sewage treatment are ‘aerobic’ – that is, the bacteria used to break down the waste products takes in oxygen to perform their function. This, results in high-energy requirements (oxygen has to be supplied by air blower or aerators) and a large volume of waste bacteria (‘sludge’) is produced. At present in Malaysia, sewage treatment processes are mainly aerobic in nature.
Waste water can also be treated by ‘anaerobic’ process. The bacteria in ‘anaerobic’ process do not use oxygen. Sludge production is much less than for aerobic processes, making the processes cheaper and simpler. There is no energy input required for the anaerobic process itself, except for any pumping. Sludge production is 0.04kg per kg BOD reduced and dry solid content is 3 to 5%, compared to 0.6 to 1kg sludge production and 1% DS respectively for aerobic process. The higher the DS, the lesser is the volume, and better sludge processing and drying. Also, the temperature range in which the bacteria like to work is very much suited for hot climates.
GRASS™ Reactor – Gas Releasing Anaerobic Sludge System is the most novel, innovative, energy efficient and space saving treatment compared to conventional aerobic processes for removing organic matter from effluent. It operates entirely as a suspended growth system and consequently utilizes no packing material.
It is basically a dense blanket of granular or flocculated sludge placed in a reactor, which is designed to allow the upward movement of wastewater through the blanket. In GRASS™ reactor, bacteria are immobilized by the process of the spontaneous aggregation of bacteria to dense compact granules with high activity and good settling characteristics.
The changes occurring during digestion are complex and arise from activities of many different type of micro-organism. Complex organic matter is broken down to soluble compounds, which are hydrolyzed, mineralized and gasified.
The anaerobic bacteria in the UASB reactor reduces the organic compounds in the waste water to energy rich methane (70–80%), carbon dioxide (20–30%) and a small amount of cell material (1-5%). The biogas, which has poor solubility in water, is separated at the top of the reactor. On bigger facilities the gas quantity may be high enough for harnessing and utilization.
Pre- screened raw sewage will pass through a grease/grit removal treatment and then to a balancing tank (BT), which will cushion out the peak flows."From BT, sewage flows at average flow rate to GRASSTM Reactor." From this it flows to aeration/clarification (chlorination, if required) and to discharge point.
Specification of GRASS™ Reactor
Reactor will be of concrete construction, approximately 5.0m to 5.5m height above ground level or partially buried under ground level, consisting of distribution chamber, supernatant flow channels, sludge drain valves, sampling points, gas dome and suitable gas discharge with safety flame arrestor. Depending on the size of reactor a gas flare will be provided (for STP above 10,000 PE).
Uniqueness of the GRASS™ system is it has simple separation system for gas, sludge and supernatant with modular construction patterns. The distribution of feed stock is innovatively designed to have non turbulent, quiescent up-flow, to make good substrate contact with the suspended sludge. This is more applicable to very low strength, high volume flow effluents with possible occasional bulky floating solids (like municipal sewage).
As organic loading rate is much higher than aeration systems for unit of foot print, plant area required will be reduced, proportionately.
As sludge yield is only about 10% of equivalent aeration system sludge yield, sludge treatment facility (i.e. SD Beds, belt presses, etc) size will be reduced. So, total plant footprint will be reduced by about 25% after all buffer zone provision. The areas saved may be returned to developer.
Features of the GRASS System:
- Small foot print
- Low energy requirement
- No moving parts inside the reactor. As such after commissioning very little maintenance is required. No major operator involvement required.
- Very little monitoring required.
- Modular construction is adapted which helps to expand the capacity easily.
- No smell problem, as it is enclosed
- After long shut down, operation can be revived fast
- Less sludge production compared to conventional activated sludge, extended aeration or simple ponding systems, for the same COD load reduction
- Expected minimum
- COD reduction 60%
- BOD reduction 70%
Overall Savings Compared to Conventional STP
- Electricity - 35% and above
- Sludge reduction - 34% and above
- Footprint - 25% less area
- Biogas production - 0.5 cu m/1Kg COD destroyed. When plants are very big, there is potential to use this biogas.
For one million population sewage treatment plant, GRASS™ system can easily save RM 1 million in electricity, annually.
Presently GRASS™ System is used successfully in low BOD strength sewage treatment plant in Malaysia, giving around 70% BOD reduction efficiency and thus reducing energy needs in subsequent aeration step to meet discharge standard.
Green & Smart can offer further treatment as aeration system, polishing etc., to meet pollution discharge limits of the country. Discharge water can be purified and recycled.
GRASS™ is a patented system of Green & Smart Sdn Bhd. Licensing arrangements can be considered
- Sewage Treatment Plant with GRASS Reactor
The innovative GREENPAK™ individual septic tank (IST) consists of two fundamental biological treatments; anaerobic and aerobic.
This invention relates in general, to a sewage treatment system, mainly as an individual septic tank (IST) for individual houses. The same can be used for other waste water treatment (of similar character).
There are many individual septic tank designs which utilizes anaerobic as initial stage treatment followed by some sort of aerobic treatment. Many times the present IST does not meet the Department of Environment discharge Standard ‘A’ stipulated for sewage. This happens especially when the tank is operating for some time and sludge occupies substantial volume of the tank. At this point it needs to be desludged for renewal to original condition.
Present invention uses anaerobic biological treatment as first phase and aerobic biological treatment as second phase.
The raw sewage is fed (from the last domestic inspection cover of the house toilets) vertically to the bottom of the tank by a down pipe. [Other systems feed sewage at side]
This sewage flows upwards due to hydraulic differential head in the tank. When sewage flows upwards it is hurdled with an inclined plate so it has to flow radially to outer diameter of tank. This sewage flows up passing through anaerobic sludge blanket. Flow path is increased by diverter plates.
Upward moving liquid will contain gas particles and sludge. Gas will separate and go up and vented out while the sludge will drop down, when buoyancy is lost.
A vertical baffle will retain any floating matter such as grease. Cleaner liquid will flow out through a liquid trap into an annular ring.
The liquid discharges through a venturi arrangement to the ring, creating vacuum and suction of outside air and mixes with the liquid. This passes through an annular ring partially filled with carrier material. Aerobic bacteria attached to these carrier materials purify the liquid further by aerobic biological activity.
Finally the liquid is discharged from the tank to drain or drain field.
The main intention of this project is to develop a new septic tank system which avoids frequent removal of accumulated solids and have better treatment efficiency GREENPAK™ individual septic tank is patented and available for licensing for commercial production.
Following are the main findings of an independent report by UTM:
- GREENPAK shows an average 69.9% COD removal efficiency
- GREENPAK shows 68.3% BOD removal efficiency
- Stable pH was observed throughout the sampling period
- Lower production of sludge seen in GREENPAK
- Moderately low suspended solids in the GREENPAK
GREENPAK’s aeration device increases D.O level for aeration section.
The system particularly relates to a process for enrichment and compression of biogas so as to produce gas having enhanced thermal efficiency/high heating value. Specifically the system provides a process for converting biogas to a gas that has varied energy related industrial and commercial applications in addition to a fuel of vehicular grade gas and scope to induct additional air for improving power output of the engine. The process of this system produces a clean fuel gas that is free of impurities. The process is low cost, simple, easy to operate and suitable for rural areas. Moreover, the process employs easily and abundantly available animal waste as raw material and converts the same to precious fuel thereby taking care of waste utilization & management and environment management also. The system also describes a device for converting biogas to a gas having enhanced thermal efficiency/high heating value. The device essentially is easy to operate, does not require any skilled personnel or sophisticated infrastructure, efficient, cost and energy saving, and industrially scalable. One of the important parts of the device is packed bed scrubber enabling counter current contact of the reactants.
The process in general comprises
- dehydrating biogas produced in the biogas digester,
- compressing the said dehydrated gas,
- contacting the gas so obtained in step (ii) in a packed bed absorber containing scrubber adopting counter current
- mechanism and a water as absorbing agent to enrich biogas by removing carbon dioxide and sulphur dioxide,
- drying, finishing and compressing the gas further to produce enriched biogas with enhanced thermal efficiency/high heating value.
Water scrubbing involves the physical absorption of CO2 and H2S in water at high pressures and regeneration by a release in pressure with very little change in temperature. The system depends upon the dissolving of carbon dioxide in water to form diluted carbonic acid.
C02 + H20 = H2C03
It is the easiest and cheapest method involving use of pressurized water as an absorbent. The raw biogas is compressed and fed into a packed bed absorption column from bottom and pressurized water is sprayed from top. The absorption process is, thus a countercurrent one. This dissolves CO2 as well as H2S in water, which are collected at the bottom of the tower. This is the simplest method for enriching biogas.
The raw biogas constituting of carbon dioxide and methane is drawn from the conventional biogas plant preferably cattle dung based biogas plant and is stored in a storage tank after removing water and condensing through single stage compressor for uninterrupted supply to the packed bed absorber from the bottom. The compression is carried out by any conventional methods so as to get compression up 1.0 MPa pressure.
The gas is contacted with the liquid in a counter currently to enable effective absorption of carbon dioxide as well as H2S, which is removed from the outlet provided at the bottom. The liquid used is water preferably pressurized water to enhance the removal rate. The enriched gas collected from the top of the packed bed absorber was further dehydrated, compressed in a three stage conventional compressors up to 2 Mpa pressure.
The device as disclosed in this system herein after referred to as packed bed absorber comprising of 3 sections connected to each other by any known means like flanges nut and bolts etc. The absorber is provided with a supporting frame for firm standing on the ground.
Top section - It has provisions for water inlet pipe, water spraying system, gas outlet pipe and a safety valve. Water spraying system is connected with water inlet pipe to provide fine atomized spray of pressurized water inside the absorption column. A safety valve is provided at the upper portion to release the excess pressure as it is a pressurized column.
Middle section - In this section inert solid shapes packings are provided. Packing should be such that they provide a large interfacial surface between liquid and gas, posses desirable fluid -flow characteristics means fraction of empty space in the packed bed should be large, be chemically inert to fluids being processed, have structural strength to permit easy handling and installation and represent low cost. An open space at the bottom of the column is necessary for ensuring good distribution of the gas into the packing. Therefore, packing support must have ample free area to allow for flow of water and gas with a minimum of restriction and it must be sufficiently strong to carry the weight of a reasonable height of packing. A circular sieve with 10 mm diameter holes and 6 mm thickness was selected and fitted inside the column as packing support. Another similar sieve was provided at the top of packing which works as packing restrainer, desirable to guard against lifting of packing during a sudden gas surge. The packing material provides sufficient residence time and increased surface area to absorb maximum carbon dioxide in the water. A view glass, to see the water level inside the column and a dry type pressure gauge, to check column pressure; are also fitted at the upper portion of the middle section. In the present case Resching rings of 16 mm diameter is filled as packing.
Bottom section - This section has provisions for an inlet gas feeding pipe and a view glass at upper side. Lower side is transformed into truncated cone shape with outlet opening. It is fitted with a ball valve to control the outlet water flow. Water seal at bottom view glass is maintained by the outlet valve to avoid any leakage of the gas fed in to the scrubber.
The scrubber is designed to remove more than 95% C02. It also removes all traces of sulfides that might otherwise cause corrosion problems in the compressor or vehicles.
Performance of the Scrubber
Performance of the scrubber was determined in terms of performance index (P.I.) with variation in gas flow rates and gas pressures. To see the effect of gas flow rate on the performance of the scrubber, raw gas was fed into the scrubber at different gas flow rates under constant gas pressure i.e. 1.0 MPa. This pressure was selected as the highest % CO2 absorption was observed at this pressure as stated in the previous section. Observations on CO2 absorption were noted with variations in gas flow rates i.e. 1.0, 1.5, 2.0, 2.5 and 3.0 m3/h at 1.0 MPa gas pressure. Three sets of observations were taken and the average is reported in the table below.
Average Test Results for the Scrubber Performance at 1.0 MPa Pressure