Sorption of Pharmaceuticals, Heavy Metals, and Herbicides to Biochar in the Presence of Biosolids

Abstract

Agricultural practices are increasingly incorporating recycled waste materials, such as biosolids, to provide plant nutrients and enhance soil functions. Although biosolids provide benefits to soil, municipal wastewater treatment plants receive pharmaceuticals and heavy metals that can accumulate in biosolids, and land application of biosolids can transfer these contaminants to the soil. Environmental exposure of these contaminants may adversely affect wildlife, disrupt microbial communities, detrimentally affect human health through long-term exposure, and cause the proliferation of antibiotic-resistant bacteria. This study considers the use of biochar co-amendments as sorbents for contaminants from biosolids. The sorption of pharmaceuticals (ciprofloxacin, triclocarban, triclosan), and heavy metals (Cu, Cd, Ni, Pb) to biochars and biochar-biosolids-soil mixtures was examined. Phenylurea herbicide (monuron, diuron, linuron) sorption was also studied to determine the potential effect of biochar on soil-applied herbicides. A softwood (SW) biochar (510°C) and a walnut shell (WN) biochar (900°C) were used as contrasting biochars to highlight potential differences in biochar reactivity. Kaolinite and activated carbon served as mineral and organic controls. Greater sorption for almost all contaminants was observed with WN biochar over SW biochar. The addition of biosolids decreased sorption of herbicides to SW biochar, whereas there was no observable change with WN biochar. The WN biochar showed potential for reducing agrochemical and contaminant transport but may inhibit the efficacy of soil-applied herbicides. This study provides support for minimizing contaminant mobility from biosolids using biochar as a co-amendment and highlights the importance of tailoring biochars for specific characteristics through feedstock selection and pyrolysis-gasification conditions.

Generation, Resuspension, and Transport of Particulate Matter From Biochar‐Amended Soils: A Potential Health Risk

“…Fine particle emission is an emerging health concern because of the potential of biochar‐bound contaminants. The biochar‐mediated immobilization of heavy metal ions, pesticides, pharmaceuticals, and microbes from the soil is often an intended outcome of biochar application (Bair et al, 2016). Contaminants such as polycyclic aromatic hydrocarbons, heavy metals, dioxins, furans, and polychlorinated biphenyls can be formed or adsorbed in biochar even during biochar production, depending on the feedstock and production temperature (Gelardi et al, 2019; Hale et al, 2012; Yargicoglu et al, 2015).…”

Graphene Oxide–ZnO Nanocomposites for Removal of Aluminum and Copper Ions from Acid Mine Drainage Wastewater

“…Among these methods, adsorption offers several advantages like flexible design and operation, high removal efficiency, cost-effectiveness and easy regeneration of the adsorbents [ 3 , 7 ]. Thus, several materials have been used for metals adsorption, such as zeolites [ 10 , 11 ], activated carbons [ 12 , 13 ], biochars [ 14 , 15 ], biomaterials [ 16 ], polymers [ 17 ], metal oxides [ 18 , 19 ], nanomaterials [ 20 , 21 , 22 ], and others. So far, nanomaterials have come to the forefront mainly due to their high specific surface area, which is known as one of the main factors determining adsorption magnitude [ 7 , 23 ].…”

Detection, Occurrence and Fate of Emerging Contaminants in Agricultural Environments

“…While results showed that BCs were effective in stabilizing pesticide contaminated soils, predicting sorption capacity was made increasingly complicated by cross-effects between BCs and soil. Comparing two BC materials, Bair et al (2016) showed that sorption capacity varied between the two BCs and this difference was magnified by the concomitant addition of biosolids. They also note that for some compounds, namely agrochemicals, sequestration by BCs can limit their efficacy.…”