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Remediating Soil & Solid Waste Compost With Natural Clinoptilolite Zeolite

The incorporation of untreated or Mg-modified natural zeolite in municipal solid waste compost has been shown to reduce heavy metal concentration of corn plants growing in the remediated soil.

A primary negative result of municipal waste composts is the contamination of soils with heavy metals. Management of the composted soil must be conducted before any land application in order to prevent heavy metal uptake by plants. Total uptake of Pb, Cu, Mn, Zn, Ni, and Cd was studied in corn plants, grown in remediated soil, with and without the addition of different natural zeolite.

A greenhouse experiment tested the potential effects of composts containing natural zeolite on the distribution of heavy metals in corn plants. Natural zeolite was added to the municipal solid waste at the starting of the composting process at 5%, 10% and 15% by volume. The solid waste was processed to a size less than 60mm. The waste was mixed with zeolites at different ratios and the composting process was performed for two months. Compost was mixed every three days. 

At harvest, the heavy metals were measured in the compost and corn plants.

The application of natural zeolite in the composting process resulted in a significant reduction of heavy metals. 

The concentrations of heavy metal in root, stalk, and leaves of corn plants are shown in Fig. 3. Remarkable differences in heavy metal concentration were found among the treatments. Increasing the zeolite dosage … in applied compost significantly reduced most of the heavy metals concentrations in corn roots, stalks and leaves compared to C treatment. (Page 4)

Amount decreased of DTPA-extractable Pb, Cu, Zn, Mn, Ni and Cd in matured compost:

Natural Zeolite: 13%, 44%, 22%, 32%, 28% and 29% in comparison to zeolite-free compost. Mg modified zeolite: 14%, 47%, 25%, 36%, 43% and 36%, respectively. Mg- modified zeolite was more effective than natural zeolite, but not significantly.

http://www.innspub.net/wp-content/uploads/2018/05/JBES-Vol-12-No-3-p-361-369.pdf

Zeolite + Food & Municipal Solid Waste

Food waste is a substantial part of municipal solid waste. The average American is throwing way more than 38 million tons of food per year, and most of it is not reused. Composting provides an environmental technology to reuse food waste, turning it into valuable fertilizer-rich soil.

This study highlights how zeolite used in composting helps reduce the loss of nutrients and eliminates odor at the same time. Struite composting is a technique in composting that is used to eliminate nitrogen loss. When you compost food waste, intense acidification becomes a problem, which is commonly fixed with alkaline materials, for example, a lime. However what is actually happening when using these methods, is 50% of initial nitrogen is lost as ammonia and reduces nutritional value for organic fertilizer (Xuan 2015).  

What scientists are finding is that nitrogen loss can be reduced up to 18% through the addition of zeolite in the struvite composting process.

Citations:

Chan, M. T., Selvam, A., & Wong, J. W. C. (2016). Reducing nitrogen loss and salinity during ‘struvite’ food waste composting by zeolite amendment. Bioresource Technology, 200, 838–844. https://doi.org/10.1016/j.biortech.2015.10.093

How Much Food is Wasted in America? (2017, September 18). Retrieved November 9, 2018, from https://foodforward.org/2017/09/how-much-food-is-wasted-in-america/

Wang, X. (n.d.). Nitrogen conservation by struvite formation during the composting process with food wastes, 258. https://repository.hkbu.edu.hk/cgi/viewcontent.cgi?article=1200&context=etd_oa

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