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Synthetic fertilizers make up a significant fraction of the energy required to grow switchgrass (Panicum virgatum L.) for ethanol production. A field study compared biosolids and synthetic fertilizers on biomass yield, ethanol production, and nitrous oxide (N2O) emissions of switchgrass to determine if using an alternative source of nutrient would lower the energy density of the fuel. Minimal N2O emissions were observed the first year of the study (0.99 ± 1.5 g N2O ha−1 d−1 for biosolids), with no difference between treatments. Biosolids were added in excess of agronomic rates, and gas samples were collected immediately after irrigation for the subsequent years to examine maximum N2O emissions. Mean Year 2 emissions increased for fertilizers to 1.8 ± 8 g N2O ha−1 d−1 (n = 131) and to 3.73 ± 10.2 g N2O ha−1 d−1 (n = 130) for biosolids‐amended soils. Emissions in Year 3 were similar to Year 2. Yield was similar and ranged from 3.7 ± 5 to 11 ± 1.1 and from 5.0 ± 0.2 to 13.4 ± 1.7 Mg ha−1 for biosolids and fertilizer, respectively. The potential ethanol yield was 365 ± 28 L Mg−1 and 374 ± 34 L Mg−1 for the biosolids‐ and fertilizer‐grown grass, respectively. Greenhouse gas emissions associated with fertilizer production were considered for N, P, and K and totaled 1,653 kg carbon dioxide equivalent (CO2e) ha−1. The equivalent credits for substitution of biosolids (18 Mg ha−1) were −2,492 kg CO2e ha−1. Nitrous oxide emissions were calculated based on 1% of total N applied for agronomic applications and were 8,600 and 3,500 g N2O ha−1 for the biosolids and fertilizer treatments, respectively. Total carbon costs associated with fertilization were 2,700 kg CO2e ha−1 for fertilizer and 60 kg CO2e ha−1 for biosolids. Using measured N2O data would have resulted in lower emissions for both treatments. [ABSTRACT FROM AUTHOR]

A study was conducted to test the suitability of a range of organic and inorganic residuals mixed with municipal biosolids to create a soil amendment effective for a broad range of end uses. Biosolids suitable for unrestricted use were sourced from San Francisco, CA. Residuals including urban wood and yard waste, nut shells, biochar, and sawdust were sourced from nearby producers. Existing biosolids based soil products, peat, and a yard–food compost were used as controls. Experimental mixtures were tested for a range of soil properties, appearance, odor, germination, and growth response. Several mixtures performed as well as or better than the yard–food compost, and several performed comparably to the biosolids soil controls. Yard waste fines blended with biosolids in a 50:50 ratio by volume or yard waste fines blended with biosolids and 20% sand at 40:40:20 were highly effective across all measured indices. Mixed yard and recycled lumber fines blended with biosolids at these same ratios performed similarly well. Blends with a high percentage of char performed poorly in germination and growth response, likely as a result of elevated electrical conductivity. Certain blends such as gypsum and redwood shavings failed to mix well with biosolids to create a uniform looking material and were less visually appealing. In general, blends that met established quality control parameters for compost performed well on the measured indices. These results suggest that blending Class A biosolids with organic and inorganic feedstocks to meet quality criteria developed for compost will create marketable soil products. [ABSTRACT FROM AUTHOR]

The phosphorus saturation index (PSI) and P saturation ratio (PSR) were tested across a wide range of bioretention soil mixtures (BSMs) for their relationship to total and dissolved P in column leachate. The BSMs tested were made using different feedstocks including sand alone, food and yard waste compost, biosolids and yard compost, and high Fe biosolids. The PSI of the mixtures ranged from 0.23 ± 0.03 (biosolids and yard waste compost 15%, oyster shells 5%) to 1.26 ± 0.02 (biosolids and yard waste compost 80%). The PSR of the mixtures ranged from 0.05 ± 0 (100% sand) to 3.12 ± 0.12 (biosolids and yard waste compost 80%). A total of 12 storm events were staged using both synthetic rainwater (total P = 1.71 ± 0.3 mg L-1) and actual stormwater (total P = 0.08 ± 0.03 mg L-1). Excluding the sand-only mixture, all treatments were a source of P for the duration of the study. However both total and dissolved P concentrations decreased over time. Effluent concentrations of total P in the first event ranged from 0.59 to 75.55 mg L-1 but decreased by the final event to between 0.15 and 10.73 mg L-1. The PSR was found to be a good predictor of P leaching from all BSMs with an R2 of 0.73 for total mass of P leached across all leaching events. The PSI was a poor predictor (R2 < 0.3). The PSR also predicted total P in leachate for individual events more effectively than the PSI. Total P in the BSMs had no relationship to P in the leachate. [ABSTRACT FROM AUTHOR]

Biosolids contain inorganic and organic contaminants, including pharmaceutical and personal care products (PPCPs) that have accounted for a series of emerging contaminants, such as triclosan (TCS) and the hormone 17α-ethinylestradiol (EE2). The general aim of this study was to evaluate the effects of biosolid application on EE2 and TCS adsorption and bioavailability in soils through testing with wheat plants. For the bioavailability study, sand and two soils, Lampa and Lo Prado, were used. The sand and soils were treated using two biosolid application rates (0 and 90 mg ha), and the EE2 and TCS concentrations in the biosolids were determined as 0.54 ± 0.06 and 8.31 ± 0.19 mg kg, respectively. The concentration observed in wheat plants indicated that EE2 and TCS are mainly concentrated in the roots rather than in the shoots. Furthermore, the bioavailability of the compounds in plants depends on the properties of the contaminants and the soil. Adsorption studies showed that increasing the soil organic matter content increases the adsorption of TCS and EE2 on these substrates and that both compounds follow the Freundlich adsorption model. The desorption procedure indicated that availability for both TCS and EE2 depended on the soil type because TCS and EE2 were small in the Lampa soil with and without biosolid application and TCS increased by nearly 50% in the Lo Prado soil. The Lo Prado soil had an acidic pH (5.9) and the Lampa soil had a neutral pH of 7.3, and the organic carbon content was smaller. [ABSTRACT FROM AUTHOR]

A replicated column trial was conducted to evaluate the potential for the phosphorus saturation index (PSI) to predict P movement in bioretention soil mixtures (BSMs). The impact of compost feedstock on BSM performance was also evaluated. Three composts (biosolids/yard, yard/food waste, and manure/sawdust) were each brought to PSI values of 0.1, 0.5, and 1.0 through the addition of Fe-based water treatment residuals (WTRs) to lower the PSI and P salts to increase the PSI. A synthetic stormwater solution was used for 12 leaching events. The PSI predicted total and dissolved P concentrations in column leachate. All composts removed P at PSI 0.1. All composts were a source of P for the higher PSI values tested, with P concentrations in the leachate decreasing over time. Ammonia and nitrate from all treatments decreased over time, with all treatments showing effective N removal. Copper removal (total and dissolved) was >90% for all treatments, with the highest removal observed at PSI 0.1 for all composts. Zinc removal (total) was also greatest in the 0.1 PSI for all composts. At PSI 0.5 and 1.0, the biosolids/yard compost was less effective than the other materials at removing Zn, with a removal efficiency of approximately 50%. Infiltration rates were similar across all treatments and ranged from 0.44 ± 0.1 cm min-1 in the manure/sawdust at PSI 0.1 to 3.8 ± 2.8 cm min-1 in the food/ yard at PSI 1.0. Plant growth in the manure/sawdust compost was reduced in comparison to the other composts tested across all PSI levels. The results of this study indicate that the PSI may be an effective tool for predicting P movement in bioretention systems. Compost feedstock does not indicate the ability of composts to filter contaminants filtration, with all composts tested showing high contaminant removal.A replicated column trial was conducted to evaluate the potential for the phosphorus saturation index (PSI) to predict P movement in bioretention soil mixtures (BSMs). The impact of compost feedstock on BSM performance was also evaluated. Three composts (biosolids/yard, yard/food waste, and manure/sawdust) were each brought to PSI values of 0.1, 0.5, and 1.0 through the addition of Fe-based water treatment residuals (WTRs) to lower the PSI and P salts to increase the PSI. A synthetic stormwater solution was used for 12 leaching events. The PSI predicted total and dissolved P concentrations in column leachate. All composts removed P at PSI 0.1. All composts were a source of P for the higher PSI values tested, with P concentrations in the leachate decreasing over time. Ammonia and nitrate from all treatments decreased over time, with all treatments showing effective N removal. Copper removal (total and dissolved) was >90% for all treatments, with the highest removal observed at PSI 0.1 for all composts. Zinc removal (total) was also greatest in the 0.1 PSI for all composts. At PSI 0.5 and 1.0, the biosolids/yard compost was less effective than the other materials at removing Zn, with a removal efficiency of approximately 50%. Infiltration rates were similar across all treatments and ranged from 0.44 ± 0.1 cm min-1 in the manure/sawdust at PSI 0.1 to 3.8 ± 2.8 cm min-1 in the food/ yard at PSI 1.0. Plant growth in the manure/sawdust compost was reduced in comparison to the other composts tested across all PSI levels. The results of this study indicate that the PSI may be an effective tool for predicting P movement in bioretention systems. Compost feedstock does not indicate the ability of composts to filter contaminants filtration, with all composts tested showing high contaminant removal. [ABSTRACT FROM AUTHOR]

Abstract: A long-term research and demonstration site was established on Pb and Zn mine wastes in southwestern Missouri in 1999. Municipal biosolids and lime and composts were mixed into the wastes at different loading rates. The site was monitored intensively after establishment and again in 2012. A site restored with topsoil was also included in the 2012 sampling. Initial results including plant, earthworm and small mammal assays indicate that the bioaccessibility of metals had been significantly reduced as a result of amendment addition. The recent sampling showed that at higher loading rates, the residual mixtures have maintained a vegetative cover and are similar to the topsoil treatment based on nutrient availability and cycling and soil physical properties including bulk density and water holding capacity. The ecosystem implications of restoration with residuals versus mined topsoil were evaluated. Harvesting topsoil from nearby farms would require 1875years to replace based on natural rates of soil formation. In contrast, diverting biosolids from combustion facilities (60% of biosolids generated in Missouri are incinerated) would result in greenhouse gas savings of close to 400Mg CO2 per ha. [Copyright &y& Elsevier]

The article investigates the ability of high-iron (Fe) biosolids-based composts to reduce the bioaccessibility of soil lead (Pb) and arsenic (As) in situ. A compost with Fe added to the wastewater treatment residuals (Fe WTR compost) added to soils at 100 g kg decreased Pb bioaccessibility in laboratory conditions. Composts tested in the field, however, did not reduce bioaccessible Pb, and limited reductions were noted in bioaccessible As. The findings suggest that addition of high-Fe biosolid compost is an effective way to reduce Pb accessibility just for some types of Fe-rich materials.

A study was conducted to evaluate the effect of two biosolids based soil products on soil physical properties in urban community gardens in Tacoma, Washington. The Tagro soil product is made from Class A biosolids cake mixed with sand and sawdust. The GroCo biosolids compost is produced from biosolids cake and sawdust. Both products meet regulatory requirements for unrestricted use and are locally available to gardeners. Plots were established in 3 community gardens and maintained for 2 growing seasons. Amendments were applied at 200 Mg ha-1 dry weight in the first year of the study. Plots were split for the 2nd year with half of the amendment plots receiving an additional 200 Mg ha-1 of amendments. Although lower in most metals than the soils they were added to, biosolids did not have a significant effect on total soil metal concentrations. Biosolids addition increased the water infiltration rate from 10.1 ± 0.95 ml min-1 in control soils to between 51 ± 6.1 and 212 ± 34 ml min-1, depending on the product used. Bulk density was decreased from 1.07 ± 0.01 g cm-3 to between 0.51 ± 0.08 and 0.77 ± 0.03 g cm-3. Total carbon, nitrogen and available phosphorus were increased in the biosolids amended plots in comparison to the control plots. Biosolids addition resulted in decreased pH (5.35 -5.75) in comparison to the control soils (6.43). The results from this study indicate that biosolids-based soil amendments can be a suitable amendment for urban community gardens. [ABSTRACT FROM AUTHOR]

This study assessed the effect of biosolids applied at rates, 0, 30, 45, and 60 Mg ha on the chemical associations and bioavailability of Cu and Zn in soils from an important agricultural zone of the Metropolitan Region in Central Chile. Three methods were used to determine the bioavailability of Cu and Zn in soils: ryegrass ( Lolium perenne) plants, diffusive gradients in thin films (DGT) technique, and Community Bureau of Reference (BCR) sequential extraction. The DGT effective concentration ( C) and sequential extract acid soluble fraction of the BCR extraction (most labile fraction of the soils, normally associated with bioavailability) were compared with total metal concentration in ryegrass plants as a means to compare the chemical and biological measures of bioavailability. Total Zn was higher in comparison to Cu for all treatments. Concentrations were within the limits set by the Chilean regulations for land-applied biosolids. Metals in the control soil were primarily found in the residual fraction of soils. Biosolids application generally decreased this fraction, with a subsequent increase observed mainly in the acid soluble fraction. The contents of Cu and Zn in ryegrass plants increased with increasing rates of biosolids. Comparison of the Cu and Zn content in ryegrass plants with C, showed a good correlation for Zn. However, the C for soil Cu was only related to plant Cu for some of the soils studied. Correlation between Zn in ryegrass plants and the labile fraction of Zn as measured by the sequential extraction was excellent, with correlation coefficients >0.9, while for Cu, correlation coefficients were lower. [ABSTRACT FROM AUTHOR]

The article presents a study on biosolids or sewage sludge, and the efforts made to develop new technologies to manage and make useful products from them. It states that land application of biosolids resulted in a complete reuse of its nutrients and organic carbon at a relatively low cost. It suggests that land application then, should become a preferred management option where there is available land, the quality of biosolids meet regulatory requirements, and is socially acceptable. Intensive energy cropping and forest production using biosolids, however, can help meet the ever-incresasing demand for renewable energy that can help remove the contamination potential for food sources, which is a common social concern about land application of biosolids.

Forest fertilization with municipal biosolids has been shown to increase tree growth and enhance forest soils. However, there are concerns that nitrogen from the biosolids could impact surface waters through movement from subsurface flow. Here we analyzed data on soil and surface water nitrogen from a working tree plantation that has used biosolids for over three decades to see if there was evidence of N movement through the soil to surface waters. GIS (Geographic Information System) was used to map application units over time and LiDAR (Light Detection and Ranging) was used to delineate watersheds. The program is located in King County Washington with biosolids provided by the King County Wastewater Treatment program. We assembled records to determine if there is any evidence of movement of NO 3 − through soils or any enrichment in surface waters. While soils show evidence of NO 3 − enrichment following biosolids application with cumulative loading rates up to 26 Mg ha−1, this is generally limited to the 'A' soil horizon and does not increase linearly with increased biosolids loading rates. There was no indication of increased surface water NO 3 − concentration relative to biosolids application rates, with a small trend of decreasing water NO 3 − over time. Surface water NO 3 − concentration was not correlated with the fraction of the watershed area that had been amended with biosolids, and there was no observable increase in surface water NO 3 − with increased frequency of biosolids applications to the tree plantations. These results suggest that the current biosolids program is sufficiently protective of ground and surface waters. These observations suggest that biosolids application can be conducted on a large scale with multiple benefits and no discernible impact to surface waters. [Display omitted] • Municipal biosolids enhance tree growth and improve soil quality on tree farms. • Nitrate leaching concerns can limit application frequency and rates. • Long-term data from commercial applications was used evaluate nitrogen movement. • Biosolids increased surface soil NO 3 - but no changes in water N were observed. [ABSTRACT FROM AUTHOR]

Municipal biosolids are commonly used to fertilize Douglas fir (Pseudotsuga menziesii) plantations in the Pacific Northwest. An intensive soil sampling was conducted to quantify the effects of long-term biosolids application on soil carbon, nitrogen and bulk density for forest soils. This information was used to calculate a carbon balance for biosolids use in commercial tree plantations. Paired control and treated sites on two soil series (Klaus and Tokul) were included with samples collected to a 30 cm depth. A significant decrease in bulk density for two depths, but no changes in total C or N were observed in the Klaus soil. In the Tokul soil, biosolids fertilization increased C storage (total C * bulk density) for three of the four measured depths, resulting in an increase in total C from 112.8 Mg C ha−1 to 172 Mg C ha−1 for the 0–30 cm depth. A comparable increase in N was observed, with significant increases in N storage for all measured depths. The C balance considered fuel use associated with transport and application as costs. The fertilizer (N and P) content of the biosolids and changes in soil C were considered as credits. The balance showed net sequestration for both soil series. Carbon benefits for the Klaus soil totaled −0.2 Mg CO 2 per Mg biosolids. Benefits in the Tokul soil totaled −5.15 Mg CO 2 per Mg biosolids. Based on diameter at breast height (DBH) biosolids use also resulted in increased tree growth for both soil series. However, differences in stand age and stocking rate complicated interpretation of these results. [Display omitted] • We sampled soils and measured tree growth to document changes as a result of long-term biosolids application to commercial tree plantations in the Pacific Northwest Significant carbon and nitrogen storage were seen on the lower organic matter site. • No changes were seen on the higher organic matter site. • A carbon balance was carried and showed significant carbon storage at the lower organic matter site with a small credit at the higher organic matter site. [ABSTRACT FROM AUTHOR]