Reducing Gas and Odor Emissions from Manure Storages with Covers

The number 1 complaint of people from animal production sites are odor emissions.  This is the reason why looking for a facility that is far from residential communities pose a big problem. Moreover, the option to choose is not always a possibility for producers and therefore knowing how to reduce emissions from farms tends to be the only viable option for them.  Here is how gas collection covers are used to reduce odor emissions in farms.

Source

About 99% of odors from livestock and poultry are a result of the anaerobic decomposition of livestock waste which include urine and fecal material. Other sources of waste included as well are bedding materials, wash water and spilled feeds. The odor from this waste sources go up due to increased organic loading rates brought by a bigger animal population, lack of dilution water and concentrated streams of waste. The condition worsens when the manure is disturbed during windy conditions or when agitated from pumping before land application. Another phenomenon called spring turnover usually seen during the cold weather months also is a factor in increasing odors from manure storage sites.

Solution

The main solution for reducing odors and emissions is by using a devices like floating lagoon covers which function to establish a physical barrier that can prevent VOCs from evaporating from the liquid. Gases like hydrogen sulfide, ammonia and volatile fatty acids are the ones primarily responsible for the nasty smell. While it is true that these gases can easily be released from land application and agitation, the total emissions from sites will be reduced greatly.

Using a cover system has become quite popular with farmers that utilize manure storages and anaerobic lagoons and is fast becoming known as one of the few effective mens or controlling the emissions from these sites. While it is true that the installation of a cover system is not the ultimate solution to the problem, using it will reduce the odors enough to the point that complaints from nearby residents would be reduced.

Warning

Aside from agitation and land application other possible sources of odor release may be from the effluent of the covered storage system which likely is released during recharge. Higher levels of toxic gas may affect the health of animals and workers therefore proper suiting and monitoring is warranted.

Cover Systems used in Anaerobic Lagoon Systems

Odor emissions are a major health concern that methane producers need to address as the noxious smells from agitation and land application of anima waste products occur during the process of storage and extraction. The use of cover systems while not perfect offers a win-win solution to reduce emissions and keep it from going to nearby residential areas.

Cover Systems

Cover systems may either be permeable which allow gases to escape or impermeable or those that do not allow the gas to dissipate. Methane producers use different kinds of covers for different purposes. The most popular cover system are permeable floating covers like geotextile or straw. More often than not, natural crusts develop on dairy manure storages and therefore maybe classified as a form of permeable cover.  Impermeable plastic covers are also used a lot in farms and may either be negatively pressurized or inflatable.  Most cover systems have a lifespan of about a decade. However, there are reports of cover failure from as early as one year of use.  The average for many covers is four years. Compared to plastic covers, geotextile covers have a lessened life expectancy  and some do not have any protection from ultraviolet radiation which in turn causes greater deterioration and therefore reduced life expectancy.

Warranties

This of course depends largely on which type of vendor however plastic cover vendor normally offers warranties of up to ten years but for workmanship it does not usually extend to more than two.  For geotextile vendors, warranty on the material may be up to three years but workmanship is usually limited to a year.  According to floating tank cover experts, if the cover is likely to fail as a result of workmanship, it usually happens within the 1st year of use.

Impermeable Covers

They feature tightly sealed storage edges. It is important to note that provisions for the collection and removal of rainwater should be considered especially in areas where there is low evaporation but high precipitation.  The runoff that collected from the cover could be drained via a series of perforated collection pipes established on the surface of the cover,  these are in turn connected to a pumping system that is manually activated. Due to their impermeable nature, they will require some form of exhaust ventilation in order to prevent pressure from building up inside as a result of manure gas production. Facilities to collect and remove methane may be done through the installation of perforated gas collection pipes or exhaust fans during installation.

Minimizing Losses from Evaporation using Floating Cover Systems

Water is the world’s most precious natural resource without it life as we know it would cease to exist. In areas where there is a large amount of water loss due to arid weather conditions, there is a real need to protect the existing water supply to ensure survival. There is a myriad of water conservation methods available out there however, the best solution for open ponds, lakes and tanks is through the use of floating covers. Here is how.

How it Works

Floating covers are basically geomembranes created from sturdy plastic geotextile materials. As the name suggests, floating cover systems float on the surface of the water and therefore prevents evaporation from occurring by stopping dry air from getting into contact with the pond, reservoir or open tank system.

Floating covers also reflect a part of the incoming solar radiation and act as a barrier to the passage of vapor.  Moreover, floating pond covers can also stop evaporation from wind and is therefore considered an effective means of water conservation in open systems like ponds etc.

Many floating cover systems may be made up using black or white reinforced polyethylene with black on one side and white on the other. White floating covers are effective in the summer months or in areas like hot desert climates. It is effective because it keeps the temperature down and minimizes radiation by reflecting sunlight as opposed to letting it be absorbed.

In an open water setting such as ponds, storage tanks or irrigation water sources, further evaporation can be reduced depending on the kind of material used. The system works best if the material is made with a low transmission ratio, as well as with high reflection and absorption ratios.

Odor Reduction

Aside from preventing evaporation, floating cover systems also reduce gas emissions from lagoon systems which in effect reduces odor emissions that can be harmful to both animals and plants.

Floating covers are an effective means of conserving water in an open water setting especially in climates that are drought-ridden. It is important therefore to select a system that is best suited for the environment for which it will be used to achieve maximum effect.

What To Look Out For in Cover Systems

While it is true that protection from the external environment to prevent evaporation or to keep odors and other noxious gases in are considered top considerations when looking for a geomembrane for your open water system, chemical resistance is also another important factor to consider. It is essential that the geomembrane you ultimately select is sturdy enough to the point that it will not degrade from contact with the substance.

Importance

According to modular tank covers experts, geomembranes offer a variety of containment uses and therefore with each application a specific set of requirements for them. Chemical resistance is one of the most important features to consider especially if you are looking to contain gases within. It is important that you look to a reliable provider that offers top of the line geomembranes that are certified to be durable against a host of volatile organic compounds. Chemical resistance is considered a top priority especially in the gas and mining industries.

The number one factor that is given credence in this case is protection from the possibility of deterioration. If you know how difficult it is to look for locations that are far away from residential communities you will know how important it is to ensure that your lagoons, ponds and  irrigation ponds are safe from leaking noxious chemicals.

Chemical and corrosion resistance liners or cover systems ensure the safety and quality in applications where concern for the environment is considered a very high priority. Having good chemical resistant properties on your system will keep your costs down in the long run as the buff will increase its lifespan and prevent early deterioration which usually occurs during the 1st year of use. This feature is of paramount importance especially if there are harmful chemicals that may seep into groundwater if allowed to leak.

What to Select

According to floating tank cover experts, both reinforced ppolyethylene as well as reinforced polypropylene have very good chemical resistant properties. This makes it ideal for many chemical containment applications.  For example, RPP liners normally has a wide spectrum of chemical resistance and are therefore indicated for applications where there is a potential of leaking into precious natural water sources.

Recovering Methane Gas: A Boon to the Environment

Methane gas is produced from the anaerobic degradation of organic compounds.  It is a greenhouse gas that if properly utilized can help save the environment instead of contributing to its demise. It comes from the manure of livestock and other animals and is also available in huge amounts deep in the earth.  Here is why recovering methane gas is good for the environment.

Environmental Benefits

According to lagoon covers experts the collection of biogas can prevent methane from going into the environment and turning into a greenhouse gas. Biogas can create heat and electricity and therefore can reduce the operating cost of a farm and the surplus may be used to power a small town or city.  Using biogas may minimize the need for other fuels. This means lesser pollution from mining, drilling, burning and transporting. Using it also reduces the amount of carbon dioxide in the atmosphere an important factor in climate change.

How to Recover Methane Gas

According to gas collection covers experts a practical way of harvesting methane gas is via the installation of an anaerobic digestion system. This approach is beneficial to the environment because it uses methane as electricity which lowers energy cost as well as reduce odors and improve the handling of manure in a farm setup.  Moreover, using one also minimizes the risk for groundwater and surface contamination.

Kinds of Digesters

Covered Lagoon Digester

This is mainly used  on large-volume, liquid manure lagoons which have less than 2% solids.  In order for the methane to be collected, a floating lagoon cover is necessary as well as a gas pump. It can be used for dairy and swine operations and is ideal in areas where manure is handled as a liquid. Among the different systems available this is the simplest and cheapest one. However, it is not recommended for use in cold temperate zones.

Plug-Flow Digester

This is used for ruminant animal manure that features 11% to 14% solids. The plug goes through the digester in 15 to 20 days and features only few moving parts.

Complete Mix Digester

This is essential for manure with 2% to 10% solids. A mixing system will keep the solids in suspension which will speed up the process of digestion. They cost more to build and operate than lagoon digesters.