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How to get heavy metals safely out of sludge (and you). February 11, 2012

Posted by ourfriendben in wit and wisdom.
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Our friend Ben has been contemplating the heavy-metal content of treated sewage sludge ever since I read an article in our local paper, the Allentown, PA Morning Call, about how residents of nearby Lynn Township were furious because local farmers were applying treated sludge as fertilizer on their fields. (See my earlier posts, “Homeowners raise stink over farmers’ poop” and “The latest poop,” by scrolling down or typing the titles in our search bar at upper right.)

The sludge is supplied to the hard-working, hard-pressed farmers free, a desperately needed break when work is backbreaking and dangerous and margins are threadlike. And the organic (in the original sense of the term, as in, of organic origin) fertilizer would seem to provide the perfect solution to how to deal with the mountains of waste produced by overpopulated humans, especially in urban areas.

On its surface, the situation would appear simple: Ignorant, selfish pigs who move out to newly constructed McMansions in the country, then are outraged because farming—which has been going on in this same countryside for generations—is a messy, smelly, noisy, and sometimes ugly business. However, the situation is actually far from simple. 

To be certified as an organic grower, you must refuse to use this free, natural fertilizer, though you may use animal excrement, as long as the animals in question haven’t been dosed with antibiotics, growth hormones and the like. Why? Because, as astute readers have pointed out, sewage sludge doesn’t just contain sewage. It also contains effluent from factories and pretty much anything else anybody chooses to flush or dump down a drain. The compaction process that renders raw sewage into sewage sludge may remove the water, and the treatment applied to turn sewage into treated sludge may remove pathogens, but the process concentrates inert contaminants like heavy metals, which can then migrate into water, crops, livestock, and, ultimately, you. Nobody wants a shot of heavy metals with their steak or glass of iced tea. So what’s the answer?

Turns out, there is one, but as with so many things in life, its discovery was entirely serendipitous, at least for our friend Ben. I learned the answer for one reason, and one reason only: because Silence Dogood is a vegetarian.

Silence became a vegetarian in her early twenties, and was appalled at the lack of genuinely delicious vegetarian fare available at the time. It seemed that you had two choices: eat meat, or eat a heavy, tasteless diet of all-brown food. She determined to address this situation, and her delicious dishes continue to delight me and our other non-vegetarian friends.

Good taste is essential, in Silence’s opinion. But as we’ve become a bit longer in the tooth and broader in the waist, healthy eating has become more important, too. We’ve always enjoyed tons of vegetables and fruits and huge, hearty salads, and almost never indulge in dessert (sob!). But recently, Silence has been investigating a diet focused on less fatty dairy and including more whole grains and other healthful foods.

When a friend recommended a book called Japanese Foods That Heal, Silence was on Amazon ordering it the same day. (It’s by John and Jan Belleme, Tuttle Publishing, 2007.) Silence knows that the Japanese diet is one of the healthiest on earth, promoting long, active, cancer-free lives. But it seems that, whatever else Japanese food has to offer, pretty much every dish has fish, fish-based broth, or some kind of seafood involved, a definite no-no for a moral vegetarian like Silence. She was thrilled that none of the foods in the book were meat- or fish-based.

When Japanese Foods That Heal arrived, Silence eagerly checked it out. We’ve been enjoying some of the featured 18 foods for years, including tofu, miso, toasted sesame oil, shoyu (Japanese soy sauce), tamari, shiitake and maitake mushrooms, and green tea. Others, like mirin and umeboshi plums, and soba noodles are recent additions to Silence’s culinary repertoire. And she’s looking into still others, like kuzu (kudzu root), daikon, and burdock root. But one of the foods on the healing foods list hadn’t made it into our culinary vocabulary, and that was seaweed.

Sea vegetables, as it’s now PC to call the various species of culinary seaweed, are one of the 18 Japanese foods that heal for a very good reason: They are packed with vitamins, minerals, micronutrients, and other good things. That’s why Silence and I and bazillion other organic gardeners have applied liquid seaweed to our container plants, misted it over our crops as a foliar feed, and spread kelp meal around our crops for a healthy harvest.

But eat seaweed ourselves?! Yes, it’s a super-healthy staple of the Japanese diet. And folks in the U.S. raised on the sushi craze will at least be getting plenty of nori seaweed wrapped around their entrees. But Silence and I were raised in the American South pre-sushi, where fried chicken, barbecue, roast beef, mashed, baked, or sweet potatoes, green beans and salad were dietary staples. Seaweed?! OMG. On our plants, yes. But us? Eat? Seaweed?! Yikes. Not because it’s seaweed per se, mind you. It’s that pungent, briny smell and taste. 

Silence, however, pointed out a bit of text promoting seaweed in the Japanese Foods That Heal book. And as it happened, what she was highlighting directly addressed the whole heavy metal/sewage sludge issue. According to the book, a substance called alginic acid is found in brown algae seaweeds such as wakame, kombu (kelp), hijiki and arame. “Scientific researchers…have demonstrated that alginic acid binds with any heavy metals found in the intestines, rendering them indigestible and causing them to be eliminated from the body. So, any heavy metals, such as barium, cadmium, lead, mercury, zinc and even radioactive strontium that may be present in the intestines will not be absorbed by the body when alginic acid is present… What’s more…the alginic acid in sea vegetables actually helps bind and draw out any similar toxins that are already stored in our bodies…”

Good news, and another good reason to include “sea vegetables” in your diet, in sushi, in miso soup, in stir-fries, salads, or any other dish that appeals to you. Silence has mastered a fabulously flavorful soup of her own creation that includes such healing ingredients as onion, garlic, shiitake and maitake mushrooms, ginger, and hot chili oil, as well as shredded carrots, red bell pepper, tofu, miso, shoyu, organic whole-grain ramen noodles (they’re not fried, Silence points out), sea veggies, and arugula, among bazillion other things. It’s so delicious that I honestly can’t even tell I’m eating seaweed, I’m too busy slurping it down.

All good and well, you’re doubtless thinking, but what’s this got to do with sewage sludge and industrial pollution? Plenty, as it turns out. Check out the final comment on the subject from Silence’s book:

“Brown algae’s natural affinity for binding with toxic heavy metals may soon be exploited by industry. Research conducted over the last decade has shown that treating heavy metal-bearing industrial effluents with brown algae is an effective and economical way to detoxify industrial waste. The process, called ‘biomass bioabsorption’, is particularly effective for lead and cadmium.”




1. pixilated2 - February 13, 2012

This is good news. Thanks for sharing! ~ Lynda

Most welcome, Lynda!

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