Dittmarite is a naturally occurring mineral which is also produced by municipal wastewater treatment processes.It contains ammonium:magnesium:phosphate in molar ratios of 1:1.25:1, respectively.Dittmarite (MgNH 4 PO 4 •H 2 O) has a very stable crystalline structure, its solubility constant (K so ) is a product of the activity coefficient (ɣ) and the activity of the individual species that make up the compound.The conditional solubility product, P S = C T, Mg C T ,NH 4 C T ,PO 4 = K so /αMg αNH 4 αPO 4 ɣMg ɣNH 4 ɣPO 4 .A theoretical plot of -log Ps vs. pH gives a pH of 10.7 for maximum dittmarite precipitation, albeit precipitation may begin at lower pH values.The pK so for dittmarite at 25 °C is determined to be 13.359 from the final equilibrium pH values taking all relevant magnesium, phosphate and ammonium species into account.The geochemical speciation model, MINTEQA2 was used to verify the optimum conditions for the precipitation of dittmarite.Such theoretical predictions allow the control of phosphorus and nitrogen discharges from animal and municipal wastewaters and serve as key factors in preventing surface water eutrophication and groundwater pollution.

Phosphorus and nitrogen are known causes of eutrophication in rivers, lakes streams and estuaries.The sources of these nutrients are diverse and they include chemical fertilizers, CAFOs (Confined Animal Feeding Operations), land application of animal and municipal as well as industrial wastewaters.Application of manure slurries to crop land beyond allowable limits could result in high levels of phosphorus and nitrogen in runoff that negatively impact aquatic animals.Municipal wastewater treatment plants are setup to remove these nutrients from domestic and industrial wastewater through a network of treatment processes.Controlling the discharge of phosphorus and nitrogen in wastewater is a key factor in preventing eutrophication.This paper presents work done to enhance a chemical precipitation process that removes over 90% of dissolved phosphorus and nearly 20% of dissolved nitrogen from both synthetic and municipal wastewaters.The objective of the study is to remove nitrogen and phosphorus from wastewater as dittmarite, a value-added mineral fertilizer found in nature.A laboratory procedure was developed that generated significant quantities of dittmarite from various wastewaters.Pure dittmarite contains nitrogen, phosphorus and magnesium in approximate molar ratios of 1:1.2:1.2 that can support plant growth.It is produced as a wet precipitate from chemical reactions that occur in the wastewater treatment process; it can be dried for proper handling and utilization.Municipal wastewater treatment plants, high volume fish producers, CAFOs and individual rural homeowners could all benefit from this technology for on-site removal of nitrogen and phosphorus from produced wastewaters.

Sediments are heterogeneous mixtures of assorted soil separates and organic matter that serve as repositories of many pollutants. This study investigated phosphorus (P) stability in river sediments as controlled by P speciation and environmental conditions, such as temperature (T), dissolved oxygen (DO), redox conditions (Eh), and pH. It attempted to evaluate the experimental conditions under which P could potentially be tied-up in river sediments. Sediment cores samples were collected from James River, in Virginia, U.S.A. near a former dairy farm and analyzed for T, pH, Eh, carbon (C) and pertinent metal ions. Results indicated that high P concentration correlated well with Fe and had non-uniform correlations with clay, Al and Ca, which changed with depth of cores. At low pH, P concentration was higher in anaerobic than aerobic sediments and aluminum (Al) precipitation was highest at low pH, which indicated Al phosphate stability in reduced (anaerobic) conditions. Above pH 7, in aerobic environments, the Minteqa2 speciation model predicted a high stability for Al-OH species. The minerals variscite, vivianite, strengite hydroxyapatite, and two forms of magnesium hydroxide species were predicted to exist in the pH ranges used in this study. Elemental P distribution assessment using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) inferred that P could be bound either to C and Al, Fe or Mn depending on their relative abundances.

Salt tolerance in plants is a complex trait involving multiple mechanisms. Understanding these mechanisms and their regulation will assist in developing novel strategies to engineer salt-tolerant crops. In the current study, we investigated salt-tolerant mechanisms in soybean (Glycine max) cultivar WF-7 in comparison to salt-sensitive Union. In vivo and in vitro salt assays demonstrated the salt tolerance of WF-7 at the seedling stage and during germination. After a 10-day 200 mM NaCl treatment, chlorophyll content in Union was reduced by 50 % compared to a 17 % reduction in WF-7. WF-7 was also less affected by abscisic acid (ABA) and NaCl during germination than Union. Upon ABA and NaCl treatment, the ABA-responsive genes SCOF1, ASN1, bZIP44, and AAPK1 are differentially expressed in WF-7 and Union seedlings. These results suggest that salt tolerance in WF-7 is in part regulated through an ABA-dependent pathway. In addition, following a 4-day 200 mM NaCl treatment, WF-7 produced more H2O2 than Union indicating the involvement of reactive oxygen species (ROS) in regulating salt tolerance in WF-7. Yet another mechanism WF-7 employs is withholding toxic chloride (Cl−) ions from aerial tissues. Following 200 mM NaCl treatment, Cl− accumulation was mostly localized to the roots of WF-7. In contrast, most of the Cl− in Union was transported into the stems and leaves. Taken together, our results demonstrated a role of ABA and ROS in regulating salt tolerance in WF-7, and the critical role of Cl− in NaCl-induced mortality in soybean.

Excessive use of poultry litter (PL) on agricultural land is known to cause eutrophication of surface waters. Consequently, both poultry producers and PL users have to meet strict state and federal guidelines on litter storage and land application. This study examined the environmental benefits of adding lime, alum, ferrous sulfate, fly ash (FA), fluidized bed ash (FBA) and soil fix (SF) to PL for immobilizing excess phosphorus (P) while providing sufficient nutrients for proper growth of soybean [Glycine max (L.)] and corn [Zea mays (L.)] on a rotation. Amending PL with lime, alum, SF, FA and FBA significantly (p>0.05) increased corn and soybean yield. In contrast control plots that received a 10-10-10 (N-P2O5-K2) fertilizer showed lower yield and corn quality. Increased yield was observed when PL was amended with lime, alum and ferrous sulfate. Results from a soybean root, shoot, and nodule growth study indicated variability with respect to PL application and amendment use. Smaller size nodules were obtained with NPK fertilizer and PL plus lime treated plots, whereas PL with alum yielded fewer but larger nodules. Soil aggregation was significantly lower in soils treated with NPK compared to those treated with PL as indicated by water stable aggregation (WSA), mean aggregate diameter (MWD) and geometric mean of aggregate diameter (GMD) (p>0.05). Increased soil aggregation was a result of the combined effect of amendment and PL additions rather than PL alone. The amount of carbon (C) in soil aggregates was lowest with NPK and highest with PL treatments. In the presence of PL, alum and iron treatments showed higher capacities to store C and immobilize P in macro-aggregates (8 to 5 mm diameter). These results suggest that soil treatment with PL and chemical amendments, especially alum and ferrous sulfate, could result in improved crop yield, soil aggregation, carbon storage, and P immobilization.

Text: Well water samples were collected from 22 counties in Coastal Plain of Virginia specifically targeting underserved households. Among the water parameters tested in the waters, survey responses showed that total coliforms (TC), fecal coliforms (FC), nitrate (NO3), fluoride (Fl), and iron (Fe) were identified to be of greater concern. When data was looked at by demography, TC counts were the highest in water samples taken from African-American homeowners than other groups. However, there was no significant difference in TC counts when compared by income levels. Comparison by education level showed that samples from households with high school education had the worse contamination of TC. The type of plumbing used in houses had significant effect on TC counts, whereby plastic piping was more conducive to TC than either copper, galvanized metal or lead piping. Even though 22 samples showed fecal coliforms count beyond the USEPA guideline, these values were not discernable when compared by demography, income level, education or the type of plumbing used. However, among the 185 water samples collected from the Coastal Plain region, 71, 22, and 12 samples exceeded the EPA limits for Total coliform, fecal coliform, and E. coli, respectively. Survey results also indicated that well age, well depth, well type, and well casing affected NO3, Fl, and Fe concentrations. Nitrate level was predominantly higher in shallow wells (50 feet depth) than deeper (>100feet). However, variations in Fl and Fe levels were not too different regardless of depth. Well age showed variability in NO 3 levels, whereby wells drilled between 1970 and 1990 indicating high NO3 content in water samples followed by older wells (1950 - 1970) and the more recently drilled wells (1990-2000). Interestingly enough, hand dug wells showed less NO3 contamination compared with drilled wells. Well casing had greatly reduced NO3 contamination in water samples. The same is true for Fl and Fe contents. Impact Statement: The current study indicated that drinking water quality at underserved households in Virginia's Coastal Plain is in danger of contamination from various sources. Results from the study were provided to the homeowners and steps were taken to advice those households where coliform contamination exceeded drinking water standards. General water quality education and wellhead protection was provided to well owners through the Master Well-Owner Network (MWON) program. Water quality education materials are being prepared for distribution to individual underserved homes and communities.

Text: Well water samples were collected from 22 counties in Coastal Plain of Virginia specifically targeting underserved households. Among the water parameters tested in the waters, survey responses showed that total coliforms (TC), fecal coliforms (FC), nitrate (NO3), fluoride (Fl), and iron (Fe) were identified to be of greater concern. When data was looked at by demography, TC counts were the highest in water samples taken from African-American homeowners than other groups. However, there was no significant difference in TC counts when compared by income levels. Comparison by education level showed that samples from households with high school education had the worse contamination of TC. The type of plumbing used in houses had significant effect on TC counts, whereby plastic piping was more conducive to TC than either copper, galvanized metal or lead piping. Even though 22 samples showed fecal coliforms count beyond the USEPA guideline, these values were not discernable when compared by demography, income level, education or the type of plumbing used. However, among the 185 water samples collected from the Coastal Plain region, 71, 22, and 12 samples exceeded the EPA limits for Total coliform, fecal coliform, and E. coli, respectively. Survey results also indicated that well age, well depth, well type, and well casing affected NO3, Fl, and Fe concentrations. Nitrate level was predominantly higher in shallow wells (50 feet depth) than deeper (>100feet). However, variations in Fl and Fe levels were not too different regardless of depth. Well age showed variability in NO 3 levels, whereby wells drilled between 1970 and 1990 indicating high NO3 content in water samples followed by older wells (1950 - 1970) and the more recently drilled wells (1990-2000). Interestingly enough, hand dug wells showed less NO3 contamination compared with drilled wells. Well casing had greatly reduced NO3 contamination in water samples. The same is true for Fl and Fe contents. Impact Statement: The current study indicated that drinking water quality at underserved households in Virginia's Coastal Plain is in danger of contamination from various sources. Results from the study were provided to the homeowners and steps were taken to advice those households where coliform contamination exceeded drinking water standards. General water quality education and wellhead protection was provided to well owners through the Master Well-Owner Network (MWON) program. Water quality education materials are being prepared for distribution to individual underserved homes and communities.

Municipal waste treatment plants are mandated by U.S. EPA to treat domestic wastewater prior to releasing it to receiving streams. The dewatering and high temperature drying processes at the plant are considered effective in reducing microbial contaminants in the waste. The resulting solid material (biosolid) is rich in nutrients that may serve as a value-added product for plant growth. In this study, we examined the nutrient value of biosolids, their potential biological and chemical risks that could result from surface application to two Mid-Atlantic soils: Bojac (coarse-loamy, mixed, thermic Typic Hapludult) and Cullen (clayey, mixed, thermic Typic Hapludult). Soils were placed on tilt beds and packed to their respective bulk density. Biosolids were added at a rate of 2.24 Mg/ha equivalent and mixed with the top 5 cm of the soil bed. Simulated rain was applied at a rate of 65 mm h−1 for 45 minutes. Surface runoff and percolation water were collected and analyzed for elemental content, Escherichia coli (E. coli) and total coliform bacteria. Among the nutrient elements of concern (P, Zn, Mn, and Cu) in biosolids, none were found to be higher than the specified EPA limits. The concentration of P was highest in runoff and percolation water from beds packed with Bojac and biosolids. The combined effects of high clay (35%), Al (1.14%), and Fe (5.11%) in Cullen increased its P-adsorbing capacity. Low levels of E. coli and other coliform bacteria were present in samples from biosolids-treated beds packed with Cullen. Microbial counts in runoff and percolation samples varied with soil type; in some instances they were ten-fold higher in Bojac than in Cullen. The results obtained in this study suggest that surface runoff from land applications of biosolids might contribute to microbial contamination of receiving waters near agricultural fields.