What are the guidelines when it comes to Biogas in Meat Processing Plants?
With the increased global interest in the environmental and eco-friendly options over the last few years, there has been a significant increase when it comes to renewable energy sources and the use of products already in existence to power various industries. This is particularly apparent in the meat processing industry, as they use huge amounts of energy each year and produce immense levels of waste however did not, until recently, have practical solutions to address these points.
Enter the anaerobic lagoon – a suggested option that deals with animal waste, as well as producing a fuel (biogas!) that can assist with the operation of a meat processing plant. But, with the benefits that this arrangement offers, there are also some guidelines that need to be followed to manage risks. After all, there have been instances of fires an anaerobic lagoons due to biogas being released into the air, so it is crucial to ensure that they remain safe and efficient options. If you would like more information, check out the 2017 report completed by the Australian Meat Processor Corporation regarding biogas and its management.
If you have any questions, or would like to speak to Inoplex regarding biogas solutions, give us a call on 0448 307 282 and we will be able to assist.
What is a Covered Anaerobic Lagoon?
A covered anaerobic lagoon, or a CAL, is a man-made basin that is located outdoors, filled with animal waste, and is covered with high density polyethylene (HDPE), which joins up with the lagoon lining and forms a ‘seal’. The contents of a CAL undergo anaerobic (without oxygen) respiration as a pre-treatment step within a larger wastewater treatment plan, with the cover ensuring the biogas that is emitted does not make its way out into the environment. CALs are ideal for concentrated animal feeding arrangements, such as piggeries or beef cattle farms, which produce a lot of waste and generally have larger areas in which they can be located. A normal CAL is usually comprised of:
- Impermeable liner: A HDPE membrane that is used to prevent wastewater from leaking into the soil and is usually fixed into place.
- Cover: HDPE is generally used to create the cover, which is fixed into place usually through an anchor trench.
- Wastewater inlet and outlet pipes: Pipework that allows wastewater to enter and leave the lagoon surface. The inlet pipework is designed to prevent short circuiting through the lagoon volume. The outlet pipework minimises floating solids carry-over.
- Biogas collection and discharge: What is used will depend on whether the CAL is operating under positive or negative pressure. If positive, a ring main around the lagoon perimeter and under the cover is often used to collect the biogas. If negative, collection may need assistance by floats which bring the cover off the water to provide space by which the biogas can access the biogas main.
Biogas pressures are usually low for a meat industry CAL.
- Biogas release valves: Crucial for instances where biogas is unable to exit through the conventional biogas take-off point, such as blockages or long-term flare shutdown.
- Inspection ports: Allow access to the lagoon for visual inspection and instrument access.
- Weighting and stormwater removal system: Two systems that work together to minimise the stress placed on the lagoon cover.
- Sludge removal: Sludge removal systems may be installed to systematically remove accumulated sludge.
Why have a CAL instead of an Uncovered Anaerobic Lagoon?
There are both covered and uncovered anaerobic lagoons, however CALs are generally considered a better option than their uncovered counterparts. Uncovered anaerobic lagoons rely on a natural forming crust made of floating fats and fine cellulosic particles, which can be of varying thicknesses depending on the circumstances, to retain biogas and ensure it doesn’t emit into the atmosphere. This crust can crack and fracture however, which lets biogas slip through the cracks and out into the environment, which is detrimental in a variety of ways. A CAL however has, in essence, 2 ‘covers’ – a natural crust, as well as a man-made HDPE one – which offers a double-layer of insurance when it comes to biogas emitting into the atmosphere.
What is biogas?
Biogas is what’s known as a ‘biofuel’ – that is, a fuel that has been produced from living matter and is a renewable energy source. A biofuel is carbon neutral, due to the fact that the CO₂ that is created when burning it has been already removed from the environment over the organism’s life. Biogas is made up of a mixture of different gases, including methane (50-75%), carbon dioxide (25-45%), water (2-8%) and hydrogen sulphide, and is naturally created. It is generally used in the same way as natural gas, and up until quite recently, it was mostly used as a fuel for lighting and cooking but not for generating electricity. This trend is changing however with an increased focus on green energy, meaning a greater interest in biogas and how it can help in power generation. As a reference point however, biogas has about 50% of the energy content of diesel.
There are 3 main uses for biogas in the Australia meat processing industry:
- Boiler Fuel.
- Cogeneration of electricity and hot water.
Biogas in Meat Processing Plants
In addition to planning approvals and other requirements that are needed when it comes to wastewater installations (e.g. development approvals and environmental licence amendments) which can vary depending on your location, there are specific regulations for the meat processing industry which apply to biogas and its production, storage, transport and use on a meat processing site.
In Australia, biogas and the certification of biogas equipment (including associated LPG gas bottles) falls under a regulatory framework that is State or Territory-dependant. For example, biogas in Queensland is regulated by the Petroleum and Gas (Production and Safety) Act 2004*, however in NSW, it is regulated by Gas Supply (Gas Appliances) Regulation 2012* and, in Victoria, the Gas Safety (Gas Installation) Regulations 2008*.
*Please note, this was applicable at the time of posting. Regulations may have changed since this time.
Biogas safety guidelines
To ensure that the use of biogas in meat processing plants is efficient and safe, it is imperative that comprehensive safety guidelines are in place to adequately cover all usage of biogas. We have summarised some of the safety guidelines outlaid by the Australian Meat Processor Corporation, however for a full summary, read the full 2017 report as mentioned previously:
- Always have a site-specific safety management plan, or SMP, which covers the risks and associated management of any biogas system. Some States, such as Queensland and WA, have prescriptive safety management plan requirements with clear guidelines as to the content of the SMP, so make sure you complete adequate research before creating your SMP. Common inclusions are who the operator(s) of the system are, a description of the control systems, emergency response procedures and a description of the biogas system (including plant layout), just to name a few.
- Wherever practical, ensure that a CAL is located in an area that is at least 50 metres away from other major ignition sources, such as boilers and byproducts facilities with hot surfaces, as well as traffic and areas in which people regularly work. This is to safeguard infrastructure and personnel against the potential hazards that can arise due to the nature of biogas.
- Ensure an exclusion area of at least 3 metres around the CAL and any associated inlet or outlet pits.
- Erect safety signs near the main entry point to draw awareness of the hazards and required safety measures within the CAL area.
- Vegetation should be controlled around the CAL to minimise fire risks.
- Biogas piping should be at least 500mm above the max water level, to avoid a build-up of scum, foam or mousse.
- Ensure every CAL has an overpressue release system to prevent cover over inflation if biogas can’t be withdrawn for whatever reason.
- A manual isolation valve is strongly suggested in the biogas pipeline adjacent to the CAL to allow isolation of the biogas train from the CAL.
- Monitoring of biogas methane content and flow is recommended. Note, typical methane levels for biogas generated by meat processing CALs are around 65 – 75% v/v.
- Biogas combustion units, such as flares, boilers and cogeneration units, are classified as a ‘Type B’ appliance. The design of the flare-burner management system is required to comply with AS 3814-2009 (industrial & commercial gas-fired appliances) and imported flares must obtain Australian approval for use before installation.
- The CAL cover should be inspected at least weekly for leaks, damage and structural deterioration (among other things).
- Human traffic on top of the cover should be minimised where possible.
- During total fire ban days, it is recommended not to operate the flare except if the flare is a totally enclosed type.
Your experts in providing practical biogas solutions
If you have any questions regarding biogas solutions, or would like to speak to one of our knowledgeable specialists regarding possible arrangements for your property or business, give Inoplex a call on 0448 307 282 today!
*Please note, this is a guide only and should not be read in isolation. Ensure you complete your own enquiries when it comes to the production, capturing, storing and combustion of biogas in any industry, including meat processing.