ASK Piearcey

Waste Handling Odour Control in Transportable Containers
April 14, 2017, 3:03 pm
Filed under: Uncategorized

When dealing with high flow odour control systems ( e.g. waste Transfer Stations or Waste reception facilities) then we can design a variety of different orientated systems within transportable freight containers to save cost and minimise footprint.

Our designs can handle up to 67,000 m3/hr per system and typically include for the dust filtration, extraction duct as well as the extraction fan and industrial carbon adsorber itself.

In this example the System air flow requirement is 66,000 m3/hr nominal and the project included the entire system with exhaust stack. The abatement itself included 2 stage filtration  prior to the adsorber to prevent the carbon from being blinded by dust. In this case the adsorber has 2 internal beds with access for extraction and replenishment from the top. An internal baffle arrangement ensure full carbon utility and even flow through the beds.  01534644cfc1d8cc6acce003aeabcc1f7bfa83d404

The above project was undertaken through Filtrex Limited and with manufacture and installation contributions from Metalcraft Ltd.

What other Technologies are viable for the Waste Industry?


There are a range of different waste handling processes and waste types. They range from Food waste handling ( often with Anaerobic Digestion plants) to municipal and green waste handling. Within the waste types there are transfer stations, autoclaves, Dirty and clean side MRFs, Hammer mills, incineration and numerous other combinations of processes. Each of the different types of process require different approaches.

We can design systems based around adsorbers, biofilters, Regenerative or recuperative oxidisers and various types of chemical scrubbers. Sometimes a process may require more than one technology depending on the stack emission consent.

The extraction system is vital in terms of ensuring capture and containment of odours with the minimum amount of required air. The optimisation of extract air is a broad and often political aspect of the design basis. We tend to use CIBSE guides and then Chemical Engineering calculations to interrogate the process and determine the best extract philosophy. Only then can you hope to determine the optimum abatement technology.

For more details contact Andrew Piearcey :  or 07877 456718


HAZOP Service Launched
September 16, 2014, 1:09 pm
Filed under: Uncategorized | Tags: , , , , , , ,

ASK Piearcey Ltd have developed their own in-house, database driven, HAZOP process. We can now facilitate entire HAZOP events or attend as a contributor or scribe. So What is a HAZOP??

According to the  Health and Safety at Work Act 1974 (HASAW) and for Major Hazardous processes COMAH (1999) regulations, it is the responsibility of the OPERATOR or end user to identify risks associated with a plant.


There numerous regulations and protocols to refer to ( example see HSE website: ) but in our view, the End-User or operator of the plant must facilitate and attend a HAZOP for the plant as a minimum and must fully discharge their responsibilities under HASAW and where appropriate, COMAH.


A HAZOP is a study and NOT a document. Any HAZOP documentation is a product of a HAZOP study.


The HAZOP study should include but not be limited to a team of individuals with responsibility within the project to be studied as follows:


  • An electrical engineer
  • A control/software engineer
  • A mechanical engineer
  • A process engineer
  • An operator (as in person who will be physically operating that plant)
  • Project manager(s)
  • Engineers relating to specific plant items (e.g. a representative from a reactor manufacturer
  • Persons in positions of responsibility for the End User
  • Persons in positions of responsibility for the Principal contractor
  • Persons in positions of responsibility for the Planning Supervisor
  • An independent chairperson
  • An independent scribe


The HAZOP centres around the “frozen” process and instrumentation diagram (P&ID). It is a rigorous, painstaking and methodical study of each and every line within the P &ID diagram (referred to as “nodes”). Each node has a list of guide words applied to it and each guide word has a list of deviations applied to it in turn.




Guide word is “Flow”


Deviations maybe :




“Less than”

“More than”

Each application of a deviation will generate scenarios, discussion, questions about the risk and consequence of the deviation and at each stage the plant is questioned for its robustness and suitability to prevent, minimise or handle such deviations. This in turn generates actions for individuals present to rectify any perceived flaw or weakness in the design.

We have never encountered a HAZOP which has not changed the design in some manner and hence it is extremely important that a HAZOP is carried out.

HAZOP image 1 HAZOP image 2

A HAZOP may take some weeks to organise, some days to complete and some further weeks to sign-off any actions. The Actions may result in the change of the P&ID, operational instructions, drawings and design. A design cannot therefore be fit for purpose unless it has undergone a formally recorded and signed-off HAZOP.

With our  in-house designed HAZOP program, we  can carry out formal HAZOP studies. We have successfully managed and chaired HAZOPs using our database centred system. There are also companies and individuals who specialise in HAZOPs and indeed other Structured What-If Techniques (SWIFT) and they  also have fully contained database driven HAZOPS that include the procedures for issuing and signing off actions. We advise that end-users formally engage  ourselves or other specialists to facilitate HAZOPs if they do not have the capability in-house.

The HSE also advise a HAZAN (for COMAH) is undertaken as part of the hazard identification process. This is a study of the severity of a hazard in the event the risk of the hazard is realised.  In our experience, HAZANs are often not a formal, separate study but are split into actions for groups of individuals. It is advisable to fully explore the consequences of a hazard actually occurring as it may well significantly affect the methods of mitigation put in place. An example would be the potential for cross filling of sulphuric acid into a chemical tank containing sodium hypochlorite. In this event chlorine is formed and this is a highly toxic gas. At a HAZOP measures would be suggested to minimise the risk of the cross filling occurring. The HAZAN looks at what would happen to chlorine if it were formed and what consequences this would have. If the implications included  multiple fatalities then the HAZOP actions may well be made even more robust and the “budget” for mitigation increased accordingly.

It should be noted that in our experience as attendees, the “OP” part of HAZOPs is often left relatively unexplored (particularly when operators are not involved in the study) and another study known as an ALM (Access Lifting and Maintenance) can be useful in identifying and eliminating operational issues. Of course Access, Lifting and Maintenance would  simply be added as guide words to the HAZOP  if we were managing  the event and they would probably have no deviations.

For complicated projects, especially those involving several stages of treatment and with numerous interfaces with other equipment, it is advisable to implement a HAZCOM. This is a “big picture” SWIFT technique which looks at a whole process rather than individual lines on a P&ID. The purpose of a HAZCOM is to identify hazards that may arise as a result of commissioning activities. The HAZCOM needs to involve representatives from any party involved in concurrent commissioning activities. It becomes particularly relevant when there is dependency between various parties during the commissioning phase.

ASK Piearcey Ltd have attended HAZCOM events and found them to be useful in raising awareness of concurrent commissioning activities and their associated hazards.

Odour Control Systems – One of UK’s Largest Sewage OCUs

A.S.K. Piearcey Ltd were engaged by their exclusive waste-water treatment partners Plasticon UK, to carry out the process design and flow balancing of  a flag ship odour control plant situated on the South Coast.

The system handles up to 250,000 m3/hr of odorous air from the main plant and there 2 further satellite systems handling approximately 3000 m3/hr each.

ASKP Ltd provided the process design based on a concept from the main process consultant. The system comprised venturi scrubbing for dryer off-gas solids removal and acid scrubbing for ammonia removal. This was followed by caustic-hypochlorite scrubbing and final carbon adsorber polishing.

Venturi Separator Sump

Venturi Separator Sump


The venturi system handled up to 19100 m3/hr of dryer off-gas but had 2 modes of operation with automatically varied flow control set point and alarm level adjustment. The venturi throat could be varied by means of an adjustable throat plunger and worked on a constant overflow of final effluent from the separator vessel (above).

Acid Scrubber

Acid Scrubber

The Acid scrubbers handle around 47,000 m3/hr of the high odour (from direct coupled extracts) and are there primarily to remove ammonia and some of the amine present.

Hypo-Caustic Scrubbers

Hypo-Caustic Scrubbers

The Hypo-Caustic Scrubbers handle the entire air flow at 250,000 m3/hr and can temporarily handle this with just 2 of the 3 duty scrubbers in operation


Carbon loading unit

Carbon loading unit

The 3 carbon units held around 125 tonnes of copper oxide impregnated carbon to fine tune the odour control performance of the system. Each had to be loaded with a specially built carbon loading system (above).

The air was conveyed from the various field extract points via a vast network of ducting.

Field Process  Odour Extract

Field Process Odour Extract

3m diameter Combined Exhaust to Stack

3m diameter Combined Exhaust to Stack


The ducting was fabricated up to 3m internal diameter to meet the agreed velocity consents.

Carbon adsorber units, also containing copper oxide impregnated carbon were used for odour control in satellite pumping stations.

The system below shows a system with duty standby extract fans and local control panel.

Odour Control Unit at Satellite Pumping Station

Odour Control Unit at Satellite Pumping Station

The Entire project value was circa £6.5 million. ASKP also assisted with HAZOP, HAZChem and commissioning. We provided Detailed Design, Operational instructions, Control Philosophy, commissioning schedule and training for the entire odour control system.

Fan Pressure Testing by ASKP Ltd

Fan Pressure Testing by ASKP Ltd










ASK Piearcey Ltd Design Odour Control Biofilters for Spain

ASK Piearcey Ltd have designed a number of odour control systems for projects in Spain. We have partnered with JSF Hidraulica (leading manufacturers of Aluminium Covers for odour control) to provide Sewage odour control systems into

the Spanish Market

Sewage odour control 3 biofilter

The above shows the smaller of 2 bio-filters constructed from lined aluminium.

Sewage odour control biofilter

The Bi0-filter uses a porous pumice stone media for the biomass support. The media is seeded with specific bacteria to promote a biomass tailored to the contaminants found in this type of application. The installation is on the back of very successful pilot trials conducted in southern Spain by JSF, with our guidance.

The project was turnkey and ASK Piearcey Ltd also provided pressure loss calculations for fan sizing.

Odour extraction ducting

The odour containment system had general and point extraction. The smaller system was rated at 3600 m3/hr whereas the larger system was rated at 13,000 m3/hr

Rendering Odour Control

A.S.K. Piearcey Ltd were engaged by PDM (John Knights) to look at a means of improving the existing odour control at their Silvertown Facility in London.

The project was carried out in 2 stages:

Stage 1 a site visit to inspect the current system and gather the relevant design information. Which included a proposed additional test regime carried out by PDM.

Stage 2 a conceptual process design to provide a system capable of handling around 8000 m3/hr of concentrated odours which worked with the existing boiler incineration route to provide constant, seamless and reliable odour control.

The design is currently being procured for another PDM site in Nuneaton, for a larger air flow.

Our design was adapted and constructed in a very short period of time to provide an odour control safeguard in time for the London Olympics. The system was a great success, dramatically reducing the number of odour complaints, even with the additional footfall during the summer months. The design is an acid scrubber followed by a carbon adsorber (with specially impregnated, activated carbon).

The original design also included a venturi pre-scrubber for fat removal but this was not deemed necessary for the adapted design.


The design is currently being procured for another PDM site in Nuneaton, for a larger air flow.

Sewage Odour Control Pilot Trials in Spain

A.S.K. Piearcey (ASKPL) have assisted Cover manufacturing specialists JSF Hidraulica (JSF) of Madrid in developing their odour control portfolio in Spain.

After some preliminary design work by ASKPL, JSF have built and tested a pilot system (below) consisting of a bio-filter and a Carbon polisher.

JSF have tried a number of different media in the vessels to find an optimum for sewage odour control.


JSF are leaders in the aluminium structures, solid tank covers (below) and floating
tank covers market place. Odour control was a natural progression from their
various tank covering projects and they had received a number of enquiries to
provide odour abatement with their covers. They decided that a pilot trial was
an effective and economic means of developing track
record and confidence in the approach suggested by ourselves.


After extensive pilot trials involving various media they have developed a system
(with design assistance from ASKPL), which
can be used to handle the majority of the sewage odour control applications that
they come across. The bio-filter was entirely constructed from
aluminium and lined with a chemical resistant liner.


Measurements of air flow, H2S  inlet and outlet as well as temperature and irrigation were made and data-logged where practical.

The pilot trial, in Fuengirola  (south coast of Spain) was so successful that the plant manager is seeking to replace the existing scrubbers with the bio-filter approach.

JSF have since secured 2 large orders involving bio-filters and carbon adsorbers with design assistance from ASKPL.

H2S detector 1

Join Forces with Plasticon UK
June 9, 2011, 7:56 pm
Filed under: News | Tags: , , ,

Leading Equipment ManufactuerASK Piearcey Join Forces with Plasticon UK

ASK Piearcey Ltd have signed an Exclusivity deal with Plasticon UK Ltd covering odour control in the Sewage Treatment Sector.

The agreement means that ASKP Ltd and Plasticon can forge ahead with plans for development of their odour control strategies and are starting with some courses for process engineers in odour control techniques (watch out for news on this up and coming event).

The agreement is a formalisation of a successful working partnership which has developed over the last 3 years.