STRANGE BEDFELLOWS EMBRACE ENGINEERED USE OF ASH RESIDUALS

A novel partnering arrangement is developing between two unlikely entities- the Rumpke Sanitary Landfill (RSL), and the Metropolitan Sewer District of Greater Cincinnati (MSD). RSL needed a supply of nutrients for sanitary landfill vegetative growth on the intermediate slope and final cover. Finding a beneficial reuse/alternative disposal opportunity for its ash residuals (from thermal oxidation of biosolids) was a goal for MSD. RSL's environmental staff presented MSD with a concept to evaluate the ash as an additive to a soil amendment. If the concept proved acceptable, each partner could achieve measurable monetary benefits – RSL, from supplementing their supply needs for intermediate slope and final cover for the landfill, and MSD, with a beneficial reuse and alternative non-waste disposal of residuals.MSD ash, currently directed to sanitary landfill for disposal, had the potential for beneficial reuse as a nutrient supplement due to the significant level of phosphorus present. Shale use at the landfill on slopes has shown to be deficient in phosphorus. With the addition of the MSD ash, in conjunction with compost, increased levels of nutrients are available for plant growth.This study explored the effects of different ratios of compost/ash blends, a soil amendment, as a function of plant growth on the vegetative layer on the intermediate slopes and landfill cap. The one-acre application area was divided into six plots. Three plots utilized varying compost/ash blends at 1:1, 2:1, and 3:1 ratios respectively. Three additional non-ash control plots were designated as a) control (CNTRL), b) compost only (CO), and c) standard fertilizer mix only (FO).The parameters monitored included averages of shoot, root, and total, for plant growth by weight and length measurements. The results showed an increase in shoot weight with an increase in ash additions, leading to the following order for shoot growth.The influence of ash content on root growth as measured by root weight was as follows:The influence of ash content on total weight (shoots and roots) was as follows:The percent increase of growth, due to the addition of ash to compost, were found to be as large as 60% for shoot growth, 50% for root growth, and 58% for total plant weight.Shoot and root length measurements had a more consistent outcome than weight measurements. These results showed that as ash content increased, length measurements for shoot, root and total plant growth are represented by the following order:The addition of ash to compost resulted in increases in growth as measured by length, percentages as high as 62% for root growth, 30% for total growth, and 21% for shoot growth.