Herschel A. Elliott

Degraded water reuse: an overview.

Communities around the world face increasingly severe fresh water supply shortages, largely due to expanding populations and associated food supply, economic development, and health issues. Intentional reuse of degraded waters (e.g., wastewater effluents, irrigation return flows, concentrated animal feeding operations [CAFO] effluents, stormwater, and graywater) as substitutes for fresh waters could be one solution to the challenge. We describe the various degraded water types and reuse options and limitations and restrictions to their use. Emphasis is given to reuse scenarios involving degraded water applications to soil. The potential for degraded water reuse is enormous, but significant barriers exist to widespread adoption. Barriers include research questions (some addressable by traditional soil science approaches, but others requiring novel techniques and advanced instrumentation), the lack of unifying national regulations, and public acceptance. Educational programs, based on hard science developed from long-term field studies, are imperative to convince the public and elected officials of the wisdom and safety of reusing degraded waters.

Effect of water treatment sludge on growth and elemental composition of tomato (Lycopersicon esculentum) shoots

Abstract The impact of a water treatment sludge on the fertility of a silt loam soil was assessed by monitoring the yield and elemental composition of tomato (Lycopersicon esculentum) shoots in a greenhouse study. Application of sludge at rates from 2–10% (air dry weight basis) raised the soil pH from 5.3 to 8.0 which enhanced plant growth. A substantial reduction in metal (Cd, Zn, Cu, Ni) uptake was observed with sludge amendments, even at the highest rates. The alkaline nature of this sludge (pH=9.3, calcium carbonate equivalence=53%) suggests its potential use as a liming material for agricultural soils. Overly alkaline conditions should be avoided however, as high application rates combined with ammonia fertilization had an antagonistic effect on plant growth, possibly from P deficiency induced by struvite (MgNH4PO4) formation.

Managing biosolids runoff phosphorus using buffer strips enhanced with drinking water treatment residuals.

Vegetated buffers strips typically have limited ability to reduce delivery of dissolved phosphorus (DP) from agricultural fields to surface waters. A field study was conducted to evaluate the ability of buffer strips enhanced with drinking water treatment residuals (WTRs) to control runoff P losses from surface-applied biosolids characterized by high water-extractable P (4 g kg(-)(1)). Simulated rainfall (62.4 mm h(-1)) was applied to grassed plots (3 m x 10.7 m including a 2.67 m downslope buffer) surface-amended with biosolids at 102 kg P ha(-1) until 30 min of runoff was collected. With buffer strips top-dressed with WTR (20 Mg ha(-1)), runoff total P (TP = 2.5 mg L(-1)) and total DP (TDP = 1.9 mg L(-1)) were not statistically lower (alpha = 0.05) compared to plots with unamended grass buffers (TP = 2.7 mg L(-1); TDP = 2.6 mg L(-1)). Although the applied WTR had excess capacity (Langmuir P maxima of 25 g P kg(-1)) to sorb all runoff P, kinetic experiments suggest that sheet flow travel time across the buffers ( approximately 30 s) was insufficient for significant P reduction. Effective interception of dissolved P in runoff water by WTR-enhanced buffer strips requires rapid P sorption kinetics and hydrologic flow behavior ensuring sufficient runoff residence time and WTR contact in the buffer. Substantial phosphate-adsorbent contact opportunity may be more easily achieved by incorporating WTRs into P-enriched soils or blending WTRs with applied P sources.

Amendments for mitigation of dairy manure ammonia and greenhouse gas emissions: Preliminary screening

Amendments can be practical and cost-effective for reducing ammonia [NH3] and greenhouse gas [GHG] emissions from dairy manure. In this study, the effect of 22 amendments on NH3 and GHG carbon dioxide [CO2], methane [CH4] and nitrous oxide [N2O] emissions from dairy manure were simultaneous investigated at room temperature (20oC). Dairy manure slurry (2 kg; 1:1.7 urine:feces; 12% total solids) was treated with various amendments, representing different classes of product, following the suppliers’ recommended rates. In this screening of products, one sample of each amendment was evaluated along with untreated manure slurry with repeated measurements over 24 h. Gas emissions were measured after short (3 d) and medium (30 d) storage duration using a photoacoustic multi-gas analyzer. Six amendment products that acted as microbial digest, oxidizing agent, masking agent or adsorbent significantly reduced NH3 by >10% (P = 0.04 to <0.001) after both 3 and 30 d. Microbial digest/enzymes with nitrogen substrate appeared effective in reducing CH4 fluxes for both storage times. Most of the masking agents and disinfectants significantly increased CH4 in both storage periods (P = 0.04 to <0.001). For both CH4 and CO2 fluxes, aging the manure slurry for 30 d significantly reduced gas production by 11 to 100% (P <0.001). While some products reduced emissions at one or both storage times, results showed that the ability of amendments to mitigate emissions from dairy manure is finite and re-application may be required even for a static amount of manure. Simultaneous measurement of gases identified glycerol as a successful NH3 reduction agent while increasing CH4 in contrast to a digestive-microbial product that significantly reduced CH4 while enhancing NH3 release.

Developing an Environmental Manure Test for the Phosphorus Index

Abstract Widespread implementation of the phosphorus (P) index has focused attention on environmental manure tests that can be used to estimate the relative availability of P in manure to runoff water. This article describes the development and use of a water extractable P (WEP) test to assess the capacity of land‐applied manure to enrich P in runoff water. WEP of surface‐applied manure has been shown to be strongly correlated to dissolved P concentrations in runoff from agricultural soils. WEP tests that have a defined water‐to‐manure‐solids ratio and involve extraction times of 30 to 120 min provide the best prediction of dissolved P in runoff across a wide range of manures. Consistent measurement of manure WEP can be achieved with manure sample storage times of up to 22 days (4°C), acidified extract holding times of 18 days, and solid separation by either centrifugation or paper filtration. Reproducibility of WEP tests is comparable to that of other common manure tests (e.g., total P), as verified by within‐laboratory and inter laboratory evaluations. A survey of 140 livestock manures revealed significant differences in mean WEP among different livestock manures, with swine greater than poultry (turkey, broiler and layer chickens) and dairy cattle greater than beef cattle. Such results support the use of WEP‐based coefficients to modify the source component of the P index.

Serum estrogenicity and biological responses in African catfish raised in wastewater ponds in Ghana.

Reuse of wastewater for aquaculture improves the efficient use of water and promotes sustainability but the potential effects of endocrine disrupting compounds including estrogens in wastewater are an emerging challenge that needs to be addressed. We examined the biological effects of wastewater-borne estrogens on African catfish (Clarias gariepinus) raised in a wastewater stabilization pond (WSP) of a functioning municipal wastewater treatment plant, a wastewater polishing pond (WWP) of a dysfunctional treatment plant, and a reference pond (RP) unimpacted by wastewater, located in Ghana. Measurements of estrogen concentrations in pond water by liquid chromatography/tandem mass spectrometry showed that mean 17 β-estradiol concentrations were higher in the wastewater ponds (WWP, 6.6 ng/L±2.7 ng/L; WSP, 4.9 ng/L±1.0) than the reference (RP, 3.4±1.1 ng/L). Estrone concentrations were found to be highest in the WSP (7.8 ng/L±1.7) and lowest in the WWP (2.2 ng/L±2.4) with the RP intermediate (4.7±5.0). Fish serum estrogenicity assayed by E-SCREEN was significantly higher in female vs. male catfish in the RP and WSP but not in the WWP (p≤0.05). Histological examination of liver and gonad tissue showed no apparent signs of intersex or pathology in any ponds. The similarities in various measures of body indices between fish of this study and African catfish from freshwater systems suggest that aquaculture may be a suitable reuse option for treated municipal wastewater.

Comparative evaluation of residual and total metal analyses in polluted soils

Abstract Two digestion procedures, employing aqua regia‐HF (ARHF) and HNO3‐HCIO4‐HF (HHH), were used to analyze residual metals (following a chemical fractionation scheme) and total metal content of two soils, one moderately polluted by municipal sludge applications and the other a grossly‐contaminated sample (20.8% Pb) from a battery recycling site. Although commonly used in sequential extraction analyses, the ARHF method solubilized only 53% (significant at p = 0.05) of the HHH‐determined residual Pb in the battery soil. For the sludge‐amended soil, residual Cd, Pb, and Zn were not statistically different by the two methods. For the battery soil, a single ARHF extraction also underestimated total Pb and Cu relative to HHH, but both methods gave statistically‐similar total Cd, Cu, Pb, and Zn for the sludge‐amended soil. As the sample metal concentration increased, the ability of ARHF to solubilize HHH‐equivalent metal quantities generally decreased. Since the degree of contamination is often unknown for ...

Assessment of plant availability and environmental risk of biosolids-phosphorus in a U.S. Midwest Corn-Belt Soil

A field experiment was conducted from 2005 to 2008 in Fulton County, Western Illinois with biosolids from conventional wastewater treatment applied as corn fertilizer in a series of P rates (0, 163, 325, 488, 650 kg P ha(-1)) along with commercial P fertilizer - triple superphosphate P (TSP) as reference to assess biosolids-P plant availability and potential loss to waterbodies through runoff. Air-dried biosolids and TSP were incorporated into surface soil at end of 2005, and corn (Zea mays) was planted for three consecutive years (2006-2008). Concentrations of soil extractable P except for Mehlich-3 P were always lower in the biosolids than TSP treatments at the same P rates. The soil potentially available P in water extractable P (WEP) and Olsen P derived from biosolids-P estimated by the exponential depletion model was 2-4% and 15-24% of total P in the applied biosolids, respectively. The residence time of biosolids-induced WEP and Olsen P in Midwest soil under annual corn cropping was 5 and 2 years, respectively. Corn tissue analysis showed lower increase in P concentration by biosolids-P than TSP. The elevation rate of soluble reactive P (SRP) concentration in simulated runoff was less by biosolids than TSP. Based on the data in this study, the plant availability and environmental risk of biosolids-P are lower than those of TSP in the Midwest soil, thus use of biosolids as P nutrient for corn would not cause a major impairment to water sources even P applied through biosolids was not completely used by annual crop.

Characterizing Forms, Solubility, Bioavailabilities, and Mineralization Rates of Phosphorous in Biosolids, Commercial Fertilizers, and Manures (Phase I)

Laboratory and greenhouse studies were conducted to characterize P forms, solubilities, and bioavailabilities in 12 biosolids, 3 animal manures, and a commercial fertilizer (TSP). The biosolids represented a variety of treatment and stabilization methods. Manures included dairy, poultry, and poultry litter. Two acid Florida sand soils of low and moderate P-sorbing capacities, and both deficient in available P, were used as growth media for a common pasture grass (bahiagrass). Amendments were applied at total P rates to meet the P needs (low P-rate) or the N needs (high P-rate) of bahiagrass. Grass was grown from seed in greenhouse columns that allowed both relative P-source bioavailability and leachability to be evaluated. Inorganic P forms dominated all P-sources (∼ 80% of total P), including biosolids produced in the biological phosphorus removal (BPR) processes. Inorganic P was primarily in Fe- and Al-associated forms, except in two biosolids products, manures, and TSP, where Ca- and Mg-associated forms dominated. Following reaction with soil, P was primarily associated with Fe- and Al-P forms regardless of initial P-source. Above ground plant uptake of P served as the measure of P bioavailability, and was linearly regressed against applied (total) P-rate. Relative P bioavailability was determined by statistically comparing regression slopes of the organic sources of P to the slope for TSP. Phosphorous sources tended to segregate into three categories of similar bioavailability: ‘high’, ‘moderate’, and ‘low’. Biosolids produced via BPR tended to be as available as fertilizer-P, and constituted the members of the ‘high’ bioavailability group. The ‘moderate’ bioavailability category included most of the biosolids tested (representing most biosolids produced nationally), and had an average relative bioavailability of 46%. The ‘low’ bioavailability category included biosolids and manures with greater than normal total Fe and Al (e.g. > ∼30-40 g kg-1), or whose form (pellets) or associated salinity and/or alkalinity likely confounded bioavailability interpretation. Leached P was dominantly inorganic, and was much less from most biosolids than from TSP. In the poorly P-sorbing Immokalee soil, two BPR materials lost from 0.73 to 11% of the total P applied (value depended on rate and form), but no other biosolids lost > 0.42% of the applied P. About 20% of the TSP-P (high rate) was lost from this soil. In the moderate P-sorbing Candler soil, P leaching losses were much less: leaching losses of TSP varied from 1.7 to 21.7% (low and high P-rate, respectively), and no biosolids (including the BPR materials) lost > 0.45%. Apparently, differences in biosolids P leachability are effectively masked by soils with even moderate P-retention capacity. Manure-P was generally more leachable (= 4.3% lost) than biosolids-P (except the BPR materials), but significant differences were limited to the high-P rate on the Immokalee soil. No manure lost > 0.87% of applied P in the Candler soil. Biosolids-P leaching in the Immokalee soil was related to the P saturation index (PSI = [Pox] / [Alox + Feox]) of the biosolids. For biosolids with PSI = 1.25, no appreciable leaching occurred. Only BPR biosolids (PSI = 1.3 - 2.7) resulted in significant P leaching. Co-applying water treatment residuals (WTRs) with high soluble P sources can effectively eliminate leaching in soils where drainage P is a justifiable concern. Greenhouse data need validation under field conditions, but limiting biosolids applications to rates based on P crop needs appears unnecessary to minimize P leaching concerns except for BPR materials on the poorest of P-retaining soils This title belongs to WERF Research Report Series ISBN: 9781780403106 (eBook) ISBN: 9781843396581 (Print)

Linking nitrogen management, seep chemistry, and stream water quality in two agricultural headwater watersheds.

Riparian seepage zones in headwater agricultural watersheds represent important sources of nitrate-nitrogen (NO-N) to surface waters, often connecting N-rich groundwater systems to streams. In this study, we examined how NO-N concentrations in seep and stream water were affected by NO-N processing along seep surface flow paths and by upslope applications of N from fertilizers and manures. The research was conducted in two headwater agricultural watersheds, FD36 (40 ha) and RS (45 ha), which are fed, in part, by a shallow fractured aquifer system possessing high (3-16 mg L) NO-N concentrations. Data from in-seep monitoring showed that NO-N concentrations generally decreased downseep (top to bottom), indicating that most seeps retained or removed a fraction of delivered NO-N (16% in FD36 and 1% in RS). Annual mean N applications in upslope fields (as determined by yearly farmer surveys) were highly correlated with seep NO-N concentrations in both watersheds (slope: 0.06; = 0.79; < 0.001). Strong positive relationships also existed between seep and stream NO-N concentrations in FD36 (slope: 1.01; = 0.79; < 0.001) and in RS (slope: 0.64; = 0.80; < 0.001), further indicating that N applications control NO-N concentrations at the watershed scale. Our findings clearly point to NO-N leaching from upslope agricultural fields as the primary driver of NO-N losses from seeps to streams in these watersheds and therefore suggest that appropriate management strategies (cover crops, limiting fall/winter nutrient applications, decision support tools) be targeted in these zones.