Hog waste. Greenhouse gas. Now there are two things you'd never expect to be related, let alone used in the same sentence.
But we’re here to tell you that now they are related—or at least they can be for farmers who use Hoffland Environmental Inc.’s (HEI) custom-designed waste solutions for the swine-and-dairy waste industry.
HEI manufactures two types of onsite waste-breakdown systems—the HEI aerobic treatment system and the HEI anaerobic treatment system. Both are used to treat the wastewater and animal waste on a swine or dairy farm. Which system is used depends on the farmer’s needs (size of farm, amount of waste generated, etc.) and budget.
Why are these systems important? Because they can replace the traditional lagoon—which most farmers are still using—and which has many drawbacks to both animal life and the environment. Before we get into those drawbacks, however, let’s first go into how a traditional lagoon works.
Hardly The Blue Lagoon
Wastewater and animal waste are collected from the farm and run through a separator that removes liquids from solid waste. The solid manure collected is used for nursery mulch, compost, and animal feed supplements. The remaining wastewater—the liquids—is then pumped into the lagoon, which is an earthen basin created by the farmer. Once in the lagoon, the waste goes through a natural anaerobic process in which microorganisms break it down. The amount of time it takes for the waste to decompose under ambient anaerobic conditions (without heat added) is anywhere from six to 24 months. In other words, it is a long process.
As mentioned previously, there are several negatives and dangers involved in this process: 1) there’s a horrific smell produced—one that often wafts into the yards and homes of the people living near the farms (this odor is so bad, in fact, that it can make people sick); 2) if the lagoon was poorly constructed, the effluent it holds can seep into the groundwater; and 3) the effluent contains large amounts of nitrogen, which can cause other health and environmental hazards. For instance, when high doses of nitrogen are added (by dispersing treated effluent onto soil) to crops that already have adequate amounts, the excess nitrogen either runs off into nearby rivers or streams, or it percolates into the groundwater. Not only are both of these occurrences illegal, but they can also lead to eutrophication in plants (massive algae growth that causes wildlife to die) and methemoglobinemia (“blue baby” syndrome) in humans.
Options and Solutions
For all these reasons, the neighbors of farmers have been doing their best to push for legislation on the city, state, and national levels to outlaw anaerobic lagoons. As of now, there are no regulations on smells, but it just seems to be a matter of time. Which means eventually farmers will be forced to turn to a new treatment method.
The HEI aerobic treatment system is the most easily adopted alternative for farmers using conventional lagoons. It provides a more land-efficient, non-odorous, quicker, and more effective means of breaking down swine-and-dairy waste before it goes back into the field.
The HEI anaerobic treatment system is more expensive. But the long-term benefits are greater. Not only does it break down waste without the smell and by using less space—as does the aerobic treatment system—but it also entraps the methane that is naturally produced by the anaerobic process. The methane is then flared to convert it to carbon dioxide. And here’s where the recycling potential for the carbon is really maximized, as it can then be used for two purposes: 1) to generate electricity on the farm and 2) since the electricity produced is almost always more than the farm needs, the farmer can sell the remaining energy to the local utility.
Hogs and Greenhouse Gas (Huh?)
How did these two elements ever become connected? As mentioned above, with anaerobic digestion of any kind, methane is one of the natural byproducts. When burned, methane turns into carbon dioxide. HEI decided to create an anaerobic waste system that capitalized on this occurrence in such a way that the user could generate electricity on the farm and gain carbon credits. (Carbon credits are awarded to companies who have reduced their methane production. In the United States, these credits have a value of about $4 per ton of carbon dioxide. HEI works with its farmer clients to develop the full value of these credits and the best way to sell them.)
So it’s really not that these two elements aren’t related, it’s just that most people in the industry haven’t yet capitalized on the connection in the way that HEI has. The HEI anaerobic system also has political benefits. Ever since the Kyoto Conference, if a business in the United States wants to create a new refinery that burns fossil fuel, the only way it can do so is if it buys carbon credits from another company that has reduced its own carbon dioxide output. So not only does the HEI anaerobic treatment system do a more efficient job of breaking down waste—in safer way for animals, humans, and the planet—but it does so in a way that fits in with the dictates of the Kyoto Accord.
“Methane is a greenhouse gas,” elaborates Bob Hoffland, founder of HEI. “Methane is 23 times more powerful a pollutant than carbon dioxide. So with this system you’re taking one gas that is very bad and converting it into one that’s not so bad. Then you get this greenhouse gas credit from the people who cannot achieve their required reduction.” It’s a good deal all around.
The Next Step
But for now, back to the HEI aerobic treatment system. The HEI aerobic treatment system is the easiest—simplest and most economical—next-step solution for farmers using lagoons. Not only does this system create odor-free spray fields and flush water, but it also denitrifies ammonia, which prevents too much nitrogen from being produced.
With the HEI aerobic treatment system, an existing lagoon is converted into an efficient biodigester by adding a screen and a clarifier, then adding aeration to the sludge. The first step in this conversion process is to remove the solids, which starts when the screen and clarifier are added. “Our solids-separation system can remove 75%–80% of waste before it goes to the aerobic pond for further treatment, while others on the market are around 15%,” says Hoffland. “There are several screen devices typically used for removing solid waste from liquid, such as an incline screen, a rotating screen, or a screw-press screen. All work on the same principal. They all use a screen separator. But not all the waste is captured this way.”
Hoffland explains that in the case of a typical screen, about 14% of the waste material is separated by the screen, then removed from it. That means the other 86% goes through the screen, remaining with the liquid waste. When you look at the screen at this point, what is separated looks like a lot of solids. But it’s only about 14% of the solids that are being removed. So HEI created its clarifier and added it to this process.
The clarifier is a large tank. By pumping certain chemicals into it, giving it ample retention time, and having a weir at the top so that the flow rate is slowed, the solids are able to settle better at the bottom. The combined screen and clarifier remove approximately 80% of the solids.
From here, the remaining effluent goes to the aerobic basin, where aeration is added. This effectively converts it into an aerobic lagoon, making it odor-free and allowing degradation to occur much more rapidly.
The Real Waste Payoff
The HEI anaerobic treatment system is a forward-thinking system. It does what the HEI aerobic treatment system does, but it ties in responsible energy recycling and economical payoff as well. Regarding the latter, the animal-waste solids are utilized as renewable energy, and since the process produces more electricity than the farm will use, the rest of the energy can be sold to the utility.
So how does it work? The anaerobic treatment system consists of a below-grade tank, also referred to as a basin. “It has a high concentration of organic matter, which creates an environment where the microbes are happy and can grow to consume the waste,” begins Hoffland. “These microbes work best at 95-106 degrees Fahrenheit—at mesophilic temperatures—where the bacteria are aggressive and happy. The retention time is 15 days to one year, depending upon on the temperature. We like to have the basin as large as possible within the confines—the larger the basin, the more stable it operates. Also, you get increased decomposition of the organic materials. Some of these organics degrade very slowly, such as fats, lipids, and proteins. It’s better to err on the high side and have a larger unit.”
The basins are below grade and usually lined with plastic. They have a floating flexible cover that’s also made of plastic. The cover allows for the collection of methane gas, which is produced naturally from the anaerobic process. The methane is then used to generate electricity for the farm and for sale to the power grid. The liquid that remains after digestion is then further treated, aerobically, so it can more fully degrade before it is dispersed back onto
the soil.
A big benefit of this system is that it reduces the amount of land used for breaking down the waste. For instance, one of Hoffland’s clients, a swine farmer, had a permit to put in a new lagoon. However, he decided to install the HEI aerobic treatment system instead so that he would not tie up the land. “Our system has been operating on his farm for seven years,” says Hoffland. “This farmer has 5,000 sows. He treats all the waste and recycles the water, and on his farm there’s only 1 acre where the waste is aerobically treated and stored. If he didn’t do this, he would have 15 acres of anaerobic lagoon.” In addition, the farmer didn’t have to fork over the cost of creating the 15-acre lagoon.
Not only does this system save vast amounts of space, it does so while increasing the production capacity (speed and efficiency), which of course increases the overall profits for the farmer. In addition, there are no chemicals used, since the system merely encourages nature to do its job more aggressively and efficiently.
The HEI anaerobic treatment system with the electricity-generating equipment is admittedly expensive. To accommodate farmers who can’t afford it, HEI offers a simpler solution that still allows them to get carbon credits. The farmer can purchase just the cover for his existing lagoon. The cover entraps the gas, which is then flared to become carbon dioxide.
Pricing and Maintenance
The HEI aerobic treatment system is around $100,000. The HEI anaerobic treatment system with the electricity-generating equipment is around $500,000. As much as this latter system maximizes the full meaning of energy recycling, the truth is that at least for now, such an electrical-generation system in the United States is just not economical. “In most areas of the US, for incentive, the utility will pay 2 cents per kWh for purchasing non-fossil-fuel energy,” says Hoffland. “In some areas it may reach 5 cents. Now in the European countries, it is different. In Germany, for instance, they pay 22 cents per kWh. In Cyprus, they pay 15 cents per kWh. For those countries, our system is economical.”
As far as maintenance goes, the HEI aerobic treatment system must be monitored daily, with some minor repair on a yearly basis. The monitoring is done by the farmer. For the anaerobic treatment system with the generator, it costs about 1.5 cents per kWh to maintain the engines. Since it’s a more complicated machine, it requires weekly maintenance and a minor overhaul every two years. Every 4–5 years a major overhaul is needed to replace all bearings on the crankshaft.
Looking Ahead
The HEI anaerobic treatment system is now being used in other countries, particularly in Europe. Some farms in the US are installing them, however, with the help of grants. But for the smaller farmer, the HEI aerobic digester—the solids-separation system—is the more economical way to go. Currently, HEI anticipates a growing number of orders for its aerobic treatment system as new farming facilities go up.
“Right now there’s no legislature against the use of anaerobic lagoons, but the neighbors won’t let the farmers do it. With the price of pork today, farmers can afford a system like ours. Most states have cost-sharing loans through the agriculture department, too. The USDA is even giving grants to improve ecologically-friendly technology.” So how long does Hoffland think it will take until more effective (and less smelly!) waste systems like the HEI systems become the norm for swine and dairy farmers? He believes it will be a slow process, estimating maybe 5–10 years. He thinks the smell—and the complaining neighbors that go along with it—will eventually get to the farmers and the lawmakers, forcing the farmers to turn to other options.
And when that happens, Hoffland will be waiting with open arms.
Journalist Amy Sorkin Kurland specializes in marketing communications.
OW - September/October 2006 |
