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CPI Separators

Pielkenrood has been involved in developing oil/water separators right from the beginning. We are one of “the founding fathers” of the separators in use today and a leading specialist in this field. Presently we mainly use CFI and IPI separators in our designs, combining cost effectiveness with the best technical solution for each specific project.

These separation systems are used in for example: 
    •    first and second stage separators for extraction sites 
    •    oil refineries
    •    down stream plants
    •    off shore rigs
    •    ballast water and slop oil treatment facilities
    •    LNG plants
Our abilities range from preparing the basic design to delivering a complete project on a turn-key basis. Please refer for more detailed information to the next paragraphs.
 
The API
One of the earliest ways of separating oil from waste water was introduced in the 1950s with the American Petroleum Institute (API) Separator. This type of separator is a rectangular, in most cases concrete tank through which the oil containing waste water flows at a typical rate of approximately 15mm/sec.
Surface area in combination with throughput determine the efficiency of separation. Therefore API separators have to be relatively large basins.

Due to hydraulic factors such as short circuit currents and  turbulence in the separator basin, the API performance is limited to intercepting oil droplets with a minimum size of 150 micron only.


In the basic and smaller API separators, the floating oil is skimmed off at the exit side using a slotted pipe. Settled sludge is removed through a well, located at the exit side or by manual periodic draining and cleaning. Larger and more complex API separators incorporate baffles, chain-scrapers for sludge and/or surface oil.  
API separators require frequent maintenance. In addition to this they also have the following disadvantages:  
    1.    In order to achieve efficient separation, either a very low flow rate or a very long tank is needed. Still, it is impossible to avoid short circuit currents and turbulence. Thus very small particles cannot be completely separated.
    2.    Wind and rain can disrupt the liquid surface, which induces turbulence and interferes with oil skimming. This can be prevented by constructing a roof over the basin, but this is costly.
    3.    API separators generally emit a unpleasant odour.
    4.    The separated oil contains water and may require further separation.
Although the API separator served its purpose, in due course environmental regulations became stricter. As new rules could not be met by using APIs, a better separator was needed. 

The PPI
By the end of the 1950s, Royal Dutch Shell began research to improve oil/water by gravity separation. Following experiments and sophisticated hydraulic calculations,  in 1962 the Parallel Plate Interceptor (PPI) was put into use.  










The two crucial design advances were to pass the waste water between rows of parallel, flat steel plates, mounted in the direction of the flow and enclosed in a narrow deep tank of steel or concrete, and the setting of these plates at an angle, so that the rows sloped upwards at 450 from the bottom centre line of the tank in V-configuration.
The separated oil flowed up the invert sides of the plates and so to the top between the plate edges and the basin side. The plates were covered and completely enclosed by a curved steel plate, providing a semi-circular space along the length of the plates, completely filled by separated oil. Sludge and heavy particles fell to the tank base and were slowly carried by the current to a separation well at the discharge end.

Although the PPI separator offered an important improvement in separating oil from water, a major problem remained:  the efficient removal of separated oil and sludge. The solution to these problems was found by a Shell engineering, Mr. Jan Cornelissen and by Mr. Jacob Pielkenrood, who jointly invented and developed an entirely new separator: the CPI 

The CPI
Where the PPI used parallel horizontally positioned metal plates installed in a chevron configuration, the CPI used plates that were arranged in a plate pack which was installed at an angle of 45°. Another main difference was the use of corrugated plates. The separated oil droplets would collect in the tops of the corrugations, while solids would deposit in the troughs.
Separated solids would slide down and separated oil drops would adhere to the invert side of the plates and gently move upwards due to its lesser density than water. 





Mr. Pielkenrood was aware of the fact that steel plates would quickly corrode and he designed plastic plates, made of GRP. The fact that Pielkenrood-Vinitex BV was also a pioneer in the field of plastics in general and plastic welding in particular, did certainly influence this design decision. 
The use of corrugated plates also contributed to the rigidity of the plates. At the bottom and top the plate packs were fitted with chutes to guide the separated oil and sludge out of the pack.
This new separator was thoroughly tested and proved to be a considerable improvement as compared with the PPI. The design became known as the Corrugated Plate Interceptor, CPI and it was patented by Shell. Appointed licensed manufacturers were Pielkenrood-Vinitex BV of Holland, Japan Gasonline Corporation of Japan and Monarch of the USA.

CPI separators are counter current separators. Oily water enters the pack at the top and flows between the parallel plates in a downward direction. Separated oil droplets adhere to the plate surface, coalesce and move upward, counter to the downward moving main flow. The separated oil droplets leave the CPI plate pack at the top. 
Moreover CPI plate packs can also be used for the separation of heavier particles. With this application  the water enters the plate pack at the bottom side  and  moves through the pack in an upward direction. Separated particles subsequently slide down along the surface of the plates and leave the plate pack at the bottom. For this application, the angle of the plates is increased to 55° or 60°. 
The CPI was such an improvement in separating oil from water that it became Shell’s standard oil separator. Even the CPI however, had a disadvantage: clogging of the plate packs, caused by sludge accumulation in the guide chutes.
The chutes also formed an obstacle for cleaning the plate packs with water jets. The plate packs had to be lifted out of their basins before they could be cleaned. However due to the accumulated sludge, the weight of a plate pack increased significantly over time. Consequently, many a plate pack collapsed when lifted out of its basin.

Figure 4: flow pattern of CPI/TPI plate packs
The TPI

Mr. Jacob Pielkenrood introduced a modified plate pack: the Tilted Plate Interceptor or TPI. He replaced the guide chutes by strips, solving the problem of clogged plate packs and at the same time increasing efficiency with 30%. 
The increase in efficiency can be explained because the chutes caused turbulence in the water flowing between the plates. The strips in the TPI facilitate a laminar flow between the plates, thereby enhancing the plate pack’s efficiency. Pielkenrood-Vinitex patented this new design and successfully sold thousands of TPI plate packs worldwide. Many of these are still in use today. 



Our separators are of a very high quality, which is underlined by the fact that we recently replaced one of eighteen installed plate packs in a Shell oil/water separator after 30 years of service!



The CFI


The rapidly developing off shore activities of oil and gas companies generated demand for smaller separators. On rigs and platforms space is very limited and weight must be saved to the maximum possible extent.
The traditional CPI and TPI separators have a relatively small plate surface per m3 of separator basin volume and per m2 of separator basin area. It was necessary to maximise the plate surface compared to the separator basin’s dimensions. This was achieved by developing the Cross Flow Separator or CFI.





Operating principle
As with the other types of plate packs, the CFI consists of inclined, parallel corrugated plates spaced closely together. Contrary to counter current separators with the entry at the top or bottom, the CFI has an entry at the side. The water flows in a laminar stream between the plates in a horizontal direction.
The main advantage of the CFI is that heavy as well as light particles can be separated from the effluent simultaneously. For instance, oil is separated by floating upwards along the tops of the corrugated plates to the surface of the separator tank. Heavier particles at the same time settle along the bottom of the corrugated plates and slide down the plates to be collected in a sludge cone and discharged through a blow-off valve.


CFI advantages
The CFI design offers  some important advantages:
    1.    The CFI is considerably lighter and smaller than a comparable CPI or TPI.
    2.    The CFI can be designed and built in any dimension and shape, as required by the desired basin configuration as long as the total effective separator plate area meets the separation criteria.
    3.    CFI separators don’t need a deep basin, as the inlet and outlet are not located at the top or bottom, but at the side.
    4.    CFI separators separate oil as well as heavier particles simultaneously from the effluent.

Plate designs
Today we don’t exclusively use corrugated plates. Depending on the purpose of the CFI separator we determine the ideal plate design, which can be flat, corrugated or have a special profile.
It is important to know when to use which plate design. A plate profile suitable for the separation of oil from a low viscosity liquid, such as water, is not necessarily suitable for separating oil from a high viscosity liquid.



Furthermore, in the corrugated plate CFIs, the oscillating flow of the effluent between the plates causes turbulence when the flow velocity exceeds the design limits. In fact the critical flow velocity at which turbulence occurs is lower in a CFI, with corrugated plates, than in a CPI/TPI in which a linear flow exists.

Pielkenrood designs plate profiles for each specific process aiming at optimising the CFI performance.
CFI applications
CFI separators are the best solution for the following applications:
    1.    To simultaneously separate light and heavy particles from liquids.
    2.    To enhance the efficiency of existing separator tanks. For instance three phase separators, free water knock out vessels and drain water separators (especially when used on off shore facilities).
    3.    When space is limited and dimensions of the separator are dictated by the available space.
    4.    In pressurised separators.

The CFI concept is also suitable to modify existing CPI/TPI separators. By replacing the CPI/TPI plate packs by CFI type ones, the effective plate surface is increased without altering the outer dimensions of the CPI/TPI basin. Replacing CPI/TPI plate packs by CFI ones, instantly increases the plant capacity and/or separation efficiency. 
In figure 10 one can see Cross Flow plate packs applied in an existing CPI basin. The original effective CPI pack surface was 130 m2, while the effective Cross Flow pack surface is 500 m2! 
The only disadvantage of the CFI is that the flow velocity between the plates is limited.


When converting an existing CPI/TPI separator with CFI plate packs, we use mobile IPI separators in order not to disrupt our clients’ plant operation. The only disadvantage of the CFI is that the flow velocity between the plates is limited.








The IPI

Development didn’t stop with the perfection of the CPI/TPI and introduction of the CFI. We always strive to look further, to develop and to try new ideas. Often this results in a new product or application. In the 1980s Simon Pielkenrood, the son of Jacob Pielkenrood, developed such a new application: the Inclined Plate Interceptor or IPI separator.
The IPI separator combines the advantages of the counter current CPI/TPI and the compact CFI into one system. Although being a counter current separator, the IPI doesn’t make use of traditional plate packs and therefore the design of the separator basin is free. 
With the introduction of the IPI the disadvantage of the CFI, namely the limitations to flow velocity, were overcome. The IPI separator is an attractive alternative for the CPI/TPI design, in case counter current, linear flow 
separators are required.


Pressure Cross Flow Interceptor


Especially for oil and gas extraction industry, we supply pressure cross flow interceptors. These can be used to de-hydrate the oil or gas condensate after the first stage separation and for de-oiling the produced water in the second stage.The CFI plate packs are designed specially to fit into any (existing) pressure vessel and offer highly efficient operation.





We design and build new pressure cross flow interceptors, but we also refurbish existing ones in order to increase performance.

We re-fitted the separator with our own plate packs, after which it worked fine. This example shows that know-how and experience are of the utmost importance.










Our current program

Pielkenrood has been involved in developing oil/water separators right from the beginning. We are one of “the founding fathers” of the separators in use today and a leading specialist in this field. Presently we mainly use CFI and IPI separators in our designs, combining cost effectiveness with the best technical solution for each specific project. These separation systems are used in for example:  

    •    oil refineries
    •    down stream plants
    •    off shore rigs
    •    ballast water and slop oil treatment facilities
    •    LNG plants
Our abilities range from preparing the basic design to delivering a complete project on a turn-key basis.

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Physical-chemical water treatment

Pollutants can occur in water in various forms, e.g. colloidal, suspended and dissolved. This type of pollution cannot be removed as such by DAF/DGF or by settling. A physical-chemical pre-treatment is needed to render them into a separable form. This can be achieved by means of coagulation and/or flocculation.

Coagulation/Flocculation-process

In this process two successive steps can be distinguished:

1. Peri-kinetic flocculation or coagulation
Coagulation is induced by the dosing of a coagulant agent which has an electrical charge opposite to that of the pollutant particles. Subsequently the very small particles conjoin as a result of the Brownian motion, forming micro flocs. This is a rapid process taking less than a second.

jar_test2. Ortho-kinetic flocculation
This is a comparatively slow process which takes place in a flocculator. A flocculant agent is dosed and agitation of the water, generating velocity gradients is effected. The velocity gradients bring the small flocs together so that larger flocs are formed. In the initial stage of flocculator the velocity gradients, or G-values, should be as high as possible for the purpose of increasing the collisions between the microflocs, promoting floc growth. As the flocculation progresses, the G-values must gradually be decreased in order to prevent floc disruption caused by undesired excessive shearing forces. On the other hand, the G-values should not become too low as this would lead to build up of week flocs. The type of chemicals to be used and their optimum dosing rates can be determined by means of a laboratory test: the jar test. This test is performed in a series of glass beakers fitted with stirrers driven by variable speed motors. Apart from type of chemicals and dosing rates, the test (s) can also yield the parameters upon which the flocculator design is based.

Figure 1: the jar test

Coagulation/flocculation - commonly used flocculators

In conventional water treatment plants flocculation is commonly achieved in one or more continuously stirred tank reactors or in long channels fitted with stirring devices. In those flocculator types disturbing short-circuiting and back mixing effects occur. As a consequence a portion of water leaving the flocculator has been treated for an unnecessary long time. In addition, the turbulent flow patterns in this reactor cause a great variety of velocity gradients, e.g. eddy turbulence at the stirrer tips.
This combination of varying residence times and uncontrolled G-values is a major factor contributing to a disturbed floc growth. Floc structure, shape and size will differ widely, impeding subsequent separation by DAF/DGF or settling. To compensate for these poor characteristics, the retention time in conventional type flocculators is three to five times longer than those indicated by the jar test.

Coagulation/flocculation - Pielkenrood Engineering flocculators

Pielkenrood Engineering flocculators are pipe flocculators and plate flocculators, which are both based on the principles of the “tube-plug flow reactor”.

pipe_flocculator_uk_01Pipe flocculator
The pipe flocculator consists of a calculated length of pipe which is expanded in diameter along its length in order to facilitate the slower ortho-kinetic floc building up. The pipe is divided into certain lengths that are connected by 180° elbows. The result is a “coiled” pipe flocculator that can be suspended on a steel support frame. The flocculator pipe length and diameters can be exactly determined on the basis of jar test results. Chemicals can be injected into the flocculator precisely at those points where they are most effective. The energy required for the flocculation process is not derived from stirring devices but by well defined factors such as fluid velocity and pipe friction under plug flow conditions.
Figure 2: pipe flocculator installed as pre-treatment for a Dissolved Air Flotation.



plate_flocculator_01Plate flocculator
The plate flocculator consists of a number of vertical corrugated plates arranged in two or more compartments. Part of the plates are fixed, while the other plates can be moved in a vertical direction. The water flows between the plates from compartment to compartment in an alternately upward and downward direction. The first flocculator compartment is the smallest one with each successive compartment being larger. This means that the flow velocity of the water decreases in each compartment, resulting in the so-called tapered velocity flocculation.

Figure 3: typical plate flocculator


plate_flocculator_02By raising or lowering the adjustable plates a corrugation phase shift can be effected. The phase shift causes a higher flow resistance between the plates, thus creating increased G-values.The advantage of the plate flocculator is that G-values can be adjusted so that the flocculation process can be optimised to the maximum possible extent. The plate flocculators are mainly used in combination with our plate settlers in process or drinking water plants.

Figure 4: phase shift





afbeeldingPielkenrood flocculator advantages
The Pielkenrood Engineering Coiled Pipe Flocculator and Plate Flocculator give the following advantages:

    Optimal and uniform floc growth by well defined and controlled velocity gradients;
    Narrow residence time distribution;
    Narrow G-values distribution;
    Pre-calculated velocity gradients can be realised;
    Reduced chemical consumption due to well defined flocculation conditions;
    Coiled pipe configuration results in a compact flocculator;
    No moving parts in the coiled pipe flocculator, resulting in low maintenance cost;
    Chemical resistant materials;
    Easy installation and operation.

Figure 5: plate flocculator for a drinking water plant.



The Pielkenrood Engineering coiled pipe flocculators and plate flocculators are ideally suited for combination with DAF/DGF units and Cross Flow plate settlers. 

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Dissolved Air Flotation/Dissolved Gas Flotation

Dissolved Air Flotation/Dissolved Gas Flotation (DAF/DGF) is a separation technique whereby the adherence of micro gas (air) bubbles to suspended pollutants in a carrier liquid is used to enhance separation efficiency. DAF/DGF is applied when the density of the suspended pollutants is close to that of the carrier liquid so that gravity separation becomes impractical if not impossible.

Micro bubble generation
Micro bubbles can be generated by dissolving gas (air) in pressurized water and by subsequently de-pressurizing this water. In the DAF/DGF units, designed by Pielkenrood Engineering, this process is effected in a recirculation system. Part of the treated water is branched off from the DAF/DGF unit outlet and is recycled to the feed via a multistage lateral channel centrifugal pump. Gas is  added to this recycle stream at the inlet flange of the pump. This type of pump is capable of pressurizing relatively large amounts of gas together with water, causing the added gas to dissolve. Subsequently in a vent vessel, unwanted free gas is continuously bled off. From the vent vessel two different streams of gas saturated water are introduced into the DAF/DGF unit feed line.

DAF/DGF unit recirculation system
1. Feed DAF/DGF unit
2. Discharge DAF/DGF unit
3. Air/gas supply
4. Multi stage lateral channel pump
5. Free gas vent vessel
6. Free gas bleed-off
7. Supersaturators
8. Micro bubble generators


The first stream passes through a number of pipes of a small diameter and serves to supersaturate the feed without generating micro bubbles. The second stream also passes through a number of pipes of a small diameter, each of which is fitted with a micro bubble generator. In the micro bubble generators a sharp pressure drop causes the  dissolved gas to be released in the form of micro bubbles.

Feed supersaturation
Super saturation of the feed is essential in order to maintain a ”cloud” of micro bubbles of the desired size. Micro bubbles tend to re-dissolve and to implode in non supersaturated water due to their internal pressure caused by surface tension. This internal pressure is considerably higher than the hydrostatic pressure of the surrounding liquid.The smaller the bubble, the higher its internal pressure. In a non supersaturated feed, the smallest bubbles are the first lost by dissolving/imploding. The micro bubbles generated will adhere to the suspended pollutants in the feed, causing them to rise rapidly to the water surface in the DAF/DGF unit. The success of this process actually depends on the size of the micro bubbles. The smaller the bubbles, the more efficient the process.

Pielkenrood Engineering DAF/DGF units are designed to result in efficient flotation of suspended, and even of slowly setting, pollutants. The shape of the unit together with the location of the feed and discharge connections are important factors.
The average feed density, after supersaturation and after the introduction of micro bubbles, is considerably lower than the density of the treated water leaving the unit. The low density feed entering the unit quickly spreads in a horizontal direction over the surface water layer.
Along its flow path through the unit the water is depleted of micro bubbles and so its density gradually increases. This phenomena causes a stable layering or stratification effect to occur.

A logical consequence is that the feed must be introduced into the unit at a high level, while the treated water should be discharged at a low level. In this way short circuiting and turbulence are prevented and a limited residence time is achieved. Also detachment of weakly adhering micro bubbles and pollutants is greatly reduced and no micro bubbles will penetrate the lower water levels. Therefore installation of plate packs in a properly designed DAF/DGF unit is not necessary.
Depending on the nature and quantity of the feed, Pielkenrood Engineering also uses absorption columns for the dissolving of gas or air. The efficiency of all Pielkenrood Engineering DAF/DGF systems guarantees  a minimum recirculation flow rate.

 

DAF/DGF systems are used in for example:

    oil refineries
    petro chemical plants
    food industry
    oil/gas extraction

Pielkenrood Engineering DAF/DGF systems offer the following advantages over competing designs:

    Many companies use standardised systems. Pielkenrood Engineering designs and builds unique and tailor made units for each specific situation.
    We have a pool of experienced engineers available. For each project, we form a special project team, thus combining expertise with cost efficiency and flexibility.
    Our decades of experience and extensive know how enable us to analyse each and every waste water problem and to find the best possible way of treatment.

 

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SBR biological activated sludge treatment

Most biological treatment systems, particularly sewage treatment systems, are built as over designed continuous activated sludge plants. As a result of increasingly stricter environmental requirements, there is a fast growing interest in the more flexible and more efficient sequencing batch biological purification system, the SBR.

This technology isn’t new. In fact it was already in use in the first half of the 20th century, well before the continuous system gained popularity, because the sequencing batch system just offers a logical and superior treatment process. However, operating a sequencing batch system takes more control effort and was therefore relatively labour intensive as operators were needed for initiating the various process steps. When labour became more expensive, the easier to operate continuous system became the generally accepted standard, although this system was known to be less efficient and to have certain hard to control drawbacks. Today, plant automation is widely available and the batch system is now to be preferred over the continuous system.

The operation of a SBR

The main components of an SBR are:

1. The tank (reactor) in which mixing, purification and settling of activated sludge take place;
2. The waste water supply equipment (usually pumps);
3. The oxygen supply system (for example, air compressors and aeration grid);
4. The control system (for example, PLC-PC or relay panel).

The SBR biological treatment process basically involves a cycle with four distinct phases:

    Fill and treat stage
    waste water is supplied to the tank and the liquid level rises. Air is supplied as required;
    Finishing stage
    the waste water supply is shut off. Air is supplied as required;
    Discharge stage
    the aeration system is switched off. The activated sludge settles and the clear surface layer of treated water is skimmed off. The liquid level falls;
    Rest stage
    the liquid level is low. Air is only supplied in order to maintain endogenous respiration of the activated sludge kept in the tank.

Advantages of an SBR

Batch wise biological waste water treatment has great advantages compared to a continuous system, mainly because the operating and control techniques, which can be used at SBR systems, allow for a far more efficient process performance.

Biological breakdown is a natural process which has several stages and each stage requires its own specific process conditions. In a biological treatment plant, this natural process has to take place in a restricted space, in an effective manner and at minimum cost.
The population of micro-organisms, growing in a biological purification system, depends on the conditions allowed to exist in that system. Through a process of selection, mutation and competition the bio-mass adapts itself to the conditions imposed upon it. In an SBR these conditions can be easily controlled. This also implies that in the SBR we can create the optimal bio-mass properties for each specific type of waste water, while controlling these conditions is relatively simple. This cannot be achieved in continuous systems.

Other advantages of the SBR are:

    No sedimentation basin nor sludge recirculation pumps are needed. The entire process takes place in just one tank;
    No short circuiting occurs as a result of which untreated waste water leaks into the effluent;
    The system is better protected against flow and/or load variations because effluent discharge only takes place once the purification process has been completed;
    The system offers great flexibility in comparison with other activated sludge systems, because filling, processing, discharge and rest stages can be adjusted in a simple and mutually independent manner;
    Sludge management is easy to monitor and control, because the sludge always remains in the reactor and is not re-circulated from the aeration tank to the sedimentation tank or vice versa.

The Pielkenrood Engineering SBR design

The Pielkenrood Engineering SBR design offers you the following additional advantages:

    In our SBR system the periods in which a measurable concentration of oxygen can be observed are very limited;
    Our SBR systems are not operated on the basis of dissolved oxygen concentration, but on the basis of a redox potential signal, which allows for detection of oxygen surplus as well as of oxygen deficiency.

This has considerable consequences:

    The oxygen transfer is optimal, because the reactor is largely operating in a state of a slight oxygen deficiency. The result of this is that during aeration, the oxygen consumption is equal to the maximum rate of oxygen supply. So, the oxygen supply is no more than what is exactly needed, which leads to considerable energy savings;
    Aerobic and anoxic conditions alternate during the process, causing the desired nitrification and de-nitrification to take place virtually simultaneously in just one tank;
    The alternating anoxic and aerobic conditions adapted to the present BOD load stimulate the growth of phosphate reducing bacteria. In a continuous system the risk of anaerobic conditions developing in the sedimentation tank, with the sludge releasing the absorbed phosphate, is difficult to control. As a consequence phosphate will reach the effluent.

Our SBR system is designed to suppress the release of phosphate to the discharged effluent to the maximum possible extent. Our SBR systems are designed to be low load activated sludge units. The sludge load of our SBR systems is comparable with the sludge loads of extended aeration carousels and oxidation ditches.
This results in low sludge growth and consequently only a small amount of surplus sludge needs to be removed. The amount of surplus sludge from the SBR to be discharged can be further reduced by installing an aerobic sludge stabilization/thickening unit and a sludge dewatering system. The result is a considerable reduction in the cost of storing/discharging or incineration of surplus sludge.

Prevention of bulking sludge

Our control philosophy provides you with the opportunity to manipulate BOD load depending on aeration of the bio-mass, so that light filamentous bacteria have little chance to develop and grow. This prevents the forming of poorly settling sludge (bulking sludge) that creates so many problems in other, especially continuous, biological purification plants.

Conclusion

The advantages of the Pielkenrood Engineering SBR summarised:

    We use a simple construction. The whole process takes place in a single tank/reactor;
    Nitrification/de-nitrification and phosphate reduction take place more or less simultaneously and are not dependent on the location in the reactor;
    We offer great flexibility with regard to absorption of flow and/or load variations (peak and shock loads);
    We offer simple as well as more extended possibilities for controlling the conditions and progress of the purification process;
    Energy-saving by optimising the oxygen supply to the bio-mass;
    Low sludge growth due to a low sludge load;
    Well settling sludge produced by discouraging the growth of filamentous bacteria;
    Coupling of energy consumption to BOD/COD removed enables automatic control of sludge inventory and nutrients dosing;
    Integrated toxicity monitoring: abnormal treatment conditions are immediately detected.

The SBR designed by Pielkenrood Engineering combines versatility with simplicity and can be adapted over a wide range for the treatment of ”easy” or ”difficult” biodegradable material on a small or large scale. The natural potential of SBR waste water treatment is now available to you.

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Drinking water treatment

Today there are still large areas in the world where people have no access to clean and safe potable water, for instance in remote and underdeveloped areas.
But also in developing countries water supply is often a difficult task. In these countries cities are expanding at a rapid pace and the existing drinking water supply facilities cannot keep up with the increasing demand. Invariably the planning and construction of new large water supply plants just take a long time.


Pielkenrood offers a range of modular pre-fabricated, easy to install and to operate treatment units that not only can be used for the supply of safe drinking water in remote areas, but that are also eminently suitable for installation in city fringe areas where there is an immediate water supply requirement that cannot be satisfied by the existing city water works.
 

The advantages of our modular drinking water units summarised:

    Compact, skid mounted self contained units;
    The units can be quickly and easily installed without the need for complex equipment;
    The modular concept allows for a phased extension in order to meet growing water demand. This means that investments for building a large water treatment plant designed to meet future water requirements is not needed at once. Investment only needs to take place if and when necessary, limiting the use of long term credits;
    Our plants can be readily adapted to local circumstances and can be installed at almost any location;
    The plants can be easily dismounted and re-assembled at another location;
    Generally we use local sub-contractors to build and install our plants, thus saving on cost, easing logistics and shortening lead times.


In addition to modular pre-fabicated units Pielkenrood also offers full size water treatment plants. These plants are built up of large modules whereby the same principle of phased extension and thus phased investment can be applied.

Features of the full size plants are:

    Space saving of up to 75% as compared to conventional treatment plants;
    Insensitive to temperature gradients, therefore no floc carry over from the clarifiers;
    Stable and reliable plant operation with longer filter runs;
    Low operating and maintenance cost;
    Proven technology.

 

Below we describe the advantages of our drinking water units as compared to clari-flocculators.
 

To start with, our units are much smaller than clari-flocculators of a comparable capacity. Per square meter of land area the yield of our STR-plate clarifier unit is more effective by a factor of almost 3.7 as compared to that of a clari-flocculator unit.

Secondly our plants have an overflow rate which is about 74% of that of clari-flocculators. If a clari-flocculator intercepts flocs with a settling velocity of 1 m/h or higher, our plants intercept flocs with a settling velocity of 0.74 m/h. That means that in clari-flocculators more flocs will be simply carried over with the clarified water, causing shorter filter runs and thus more expensive operation.

Thirdly, the STR-plate clarifier system allows for easy, modular extension. This is an essential feature for any city planning. Cities expand and when business develops,  water demand inevitably increases. If water supply can follow this trend with easy to build modular extensions of the existing drinking water supply plant, cost can be minimized.

Finally clari-flocculators require a complex system of piping and canals to distribute the water over the plant. Applying our STR- plate clarifiers results in a simple and easy to oversee plant, requiring less civil work and thus less investment.
 

From the above it will be clear that modular type STR-plate clarifiers offer several major advantages over clari-flocculators, not only in terms of land occupation but also with regard to easy extension, flexibility and vastly superior efficiency and performance.
 

Clari-flocculators are a system that dates back from the time that plate separators were not invented yet. Since the introduction of the plate separator, plate clarifiers with their obvious advantages have become a fully accepted – and more often a preferred - system in water treatment plants.
 

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