Impact of using paper mill sludge for surface-mine reclamation on runoff water quality and plant growth

Authors: Shipitalo, Martin; Bonta, James - Jim

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2008
Publication Date: 10/23/2008
Citation: Shipitalo, M.J., Bonta, J.V. 2008. Impact of using paper mill sludge for surface-mine reclamation on runoff water quality and plant growth. Journal of Environmental Quality. 37(6):2351-2359.

Interpretive Summary: Paper mills generate a large amount of byproduct that consists of a mixture of fibers too short to make paper, clay, and lime. This material can be beneficially used by applying it to land that has been surface mined for coal production. When applied at high rates for this purpose, however, it may adversely impact the quality of the water that runs off from the reclaimed sites. In this field plot study we investigated the affect of applying paper mill byproduct at 0, 100, and 300 tons per acre on the amount and quality of runoff. We found that the byproduct drastically reduced the amount of runoff and soil erosion while improving the growth of grasses using to reclaim the mine. On the down side, the runoff from plots that were amended with byproduct was low in dissolved oxygen and contained large amounts of dissolved organic matter that may negatively impact aquatic life if it directly enters streams. The negative impact on water quality, however, was mainly observed in the first 2.5 months after the byproduct was applied. Additionally, there was little overall difference between the 100 and 300 per acre rates on water quality. Paper mill and coal mine operators and government regulators can use this information to determine the best rate to apply paper mill byproducts. Moreover, this information may be useful in designing reclamation practices that increase the beneficial effects of paper mill byproduct usage while decreasing the potential negative effects on water quality.

Technical Abstract: Paper mills generate large amounts of solid waste consisting of a mixture of fibrous cellulose, clay, and lime. Paper mill sludge (PMS) can be used to improve reclamation of surface coal mines where low pH and organic matter levels in the soil material used to cover the spoil can inhibit reestablished of vegetation. When applied at high rates for this purpose, however, PMS may adversely impact the quality of surface runoff. Therefore, we applied PMS at two rates (224 and 672 Mg/ha) to 22.1 m long by 4.6 m wide plots (RCBD with 3 reps, plus 3 no PMS controls) at an active surface mine and monitored runoff amount and quality from April 2006 to Dec. 2006 and April 2007 to Sept. 2007. Control plots were mulched with hay and fertilized at planting, but the other plots were only amended with PMS. At both rates PMS reduced runoff 4- to 6-fold and decreased erosion from 46 Mg/ha to < 1 Mg/ha compared to the control plots, with most of the reduction occurring in the 2.5 months before the plots were planted. Flow-weighted average dissolved oxygen levels in runoff from plots at both PMS rates, however, were much lower ( < 0.4 vs. 8.2 mg/L) and chemical oxygen demand (COD) was much higher for the 672 Mg/ha rate plots than in the control plots in the pre-plant period (7229 vs. 880 mg/L). Post planting there were few significant differences in water quality among treatments, but plant dry matter yields were greater for the PMS plots than for the controls. The 672 Mg/ha PMS rate did not increase COD or nutrient loads compared to the 224 Mg/ha rate and may have more persistent beneficial effects by increasing soil organic matter and pH to greater extent.