Acidified and ultrafiltered recovered coagulants from water treatment works sludge for removal of phosphorus from wastewater

This study used a range of treated water treatment works sludge options for the removal of phosphorus (P) from primary wastewater. These options included the application of ultrafiltration for recovery of the coagulant from the sludge. The treatment performance and whole life cost (WLC) of the various recovered coagulant (RC) configurations have been considered in relation to fresh ferric sulphate (FFS). Pre-treatment of the sludge with acid followed by removal of organic and particulate contaminants using a 2kD ultrafiltration membrane resulted in a reusable coagulant that closely matched the performance FFS. Unacidified RC showed 53% of the phosphorus removal efficiency of FFS, at a dose of 20 mg/L as Fe and a contact time of 90 min. A longer contact time of 8 h improved performance to 85% of FFS. P removal at the shorter contact time improved to 88% relative to FFS by pre-acidifying the sludge to pH 2, using an acid molar ratio of 5.2:1 mol H+:Fe. Analysis of the removal of P showed that rapid phosphate precipitation accounted for >65% of removal with FFS. However, for the acidified RC a slower adsorption mechanism dominated; this was accelerated at a lower pH. A cost-benefit analysis showed that relative to dosing FFS and disposing waterworks sludge to land, the 20 year WLC was halved by transporting acidified or unacidified sludge up to 80 km for reuse in wastewater treatment. A maximum inter-site distance was determined to be 240 km above the current disposal route at current prices. Further savings could be made if longer contact times were available to allow greater P removal with unacidified RC

Coagulant recovery and reuse for drinking water treatment

Coagulant recovery and reuse from waterworks sludge has the potential to significantly reduce waste disposal and chemicals usage for water treatment. Drinking water regulations demand purification of recovered coagulant before they can be safely reused, due to the risk of disinfection by-product precursors being recovered from waterworks sludge alongside coagulant metals. While several full-scale separation technologies have proven effective for coagulant purification, none have matched virgin coagulant treatment performance. This study examines the individual and successive separation performance of several novel and existing ferric coagulant recovery purification technologies to attain virgin coagulant purity levels. The new suggested approach of alkali extraction of dissolved organic compounds (DOC) from waterworks sludge prior to acidic solubilisation of ferric coagulants provided the same 14:1 selectivity ratio (874 mg/L Fe vs. 61 mg/L DOC) to the more established size separation using ultrafiltration (1285 mg/L Fe vs. 91 mg/L DOC). Cation exchange Donnan membranes were also examined: while highly selective (2555 mg/L Fe vs. 29 mg/L DOC, 88:1 selectivity), the low pH of the recovered ferric solution impaired subsequent treatment performance. The application of powdered activated carbon (PAC) to ultrafiltration or alkali pre-treated sludge, dosed at 80 mg/mg DOC, reduced recovered ferric DOC contamination to <1 mg/L but in practice, this option would incur significant costs. The treatment performance of the purified recovered coagulants was compared to that of virgin reagent with reference to key water quality parameters. Several PAC-polished recovered coagulants provided the same or improved DOC and turbidity removal as virgin coagulant, as well as demonstrating the potential to reduce disinfection byproducts and regulated metals to levels comparable to that attained from virgin material

Reuse of recovered coagulants in water treatment: An investigation on the effect coagulant purity has on treatment performance

Coagulant recovery offers many potential benefits to water treatment, by reducing chemical demand and waste production. The key obstacle to successful implementation is achieving the same levels of treatment quality and process economics as commercial coagulants. This study has evaluated the selectivity of pressure-filtration in the role of a low-cost coagulant recovery technology from waterworks sludge. The treatment performance of the purified recovered coagulant was directly compared to fresh and raw recovered coagulants. DOC and turbidity removal by recovered coagulants was close to that of commercial coagulants, indicating that coagulant can be successfully recovered and regenerated by acidifying waterworks sludge. However, performance was less consistent, with a much narrower optimum charge neutralisation window and 10–30% worse removal performance under optimum conditions. This inferior performance was particularly evident for recovered ferric coagulants. The impact of this was confirmed by measuring THM formation potential and residual metals concentrations, showing 30–300% higher THMFPs when recovered coagulants were used. This study confirms that pressure-filtration can be operated on an economically viable basis, in terms of mass flux and fouling. However, the selectivity currently falls short of the purity required for potable treatment, due to incomplete rejection of sludge contaminants

BENEFIT COST ANALYSIS OF THE 2002 EQIP FARM BILL PROVISIONS

Benefit and cost estimates for the Environmental Quality Incentives Program (EQIP) are given. The 2002 Farm Bill increased EQIP funding five fold and allows a broader scope of participation. Estimates for seven classes of environmental benefits and the sensitivity of those estimates to program implementation alternatives are included.Agricultural and Food Policy,

Dynamic PRA: an Overview of New Algorithms to Generate, Analyze and Visualize Data

State of the art PRA methods, i.e. Dynamic PRA (DPRA) methodologies, largely employ system simulator codes to accurately model system dynamics. Typically, these system simulator codes (e.g., RELAP5 ) are coupled with other codes (e.g., ADAPT, RAVEN that monitor and control the simulation. The latter codes, in particular, introduce both deterministic (e.g., system control logic, operating procedures) and stochastic (e.g., component failures, variable uncertainties) elements into the simulation. A typical DPRA analysis is performed by: 1. Sampling values of a set of parameters from the uncertainty space of interest 2. Simulating the system behavior for that specific set of parameter values 3. Analyzing the set of simulation runs 4. Visualizing the correlations between parameter values and simulation outcome Step 1 is typically performed by randomly sampling from a given distribution (i.e., Monte-Carlo) or selecting such parameter values as inputs from the user (i.e., Dynamic Event Tre

Neurotransmitter modulation of extracellular H+ fluxes from isolated retinal horizontal cells of the skate

Self-referencing H+-selective microelectrodes were used to measure extracellular H+ fluxes from horizontal cells isolated from the skate retina. A standing H+ flux was detected from quiescent cells, indicating a higher concentration of free hydrogen ions near the extracellular surface of the cell as compared to the surrounding solution. The standing H+ flux was reduced by removal of extracellular sodium or application of 5-(N-ethyl-N-isopropyl) amiloride (EIPA), suggesting activity of a Na+–H+ exchanger. Glutamate decreased H+ flux, lowering the concentration of free hydrogen ions around the cell. AMPA/kainate receptor agonists mimicked the response, and the AMPA/kainate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) eliminated the effects of glutamate and kainate. Metabotropic glutamate agonists were without effect. Glutamate-induced alterations in H+ flux required extracellular calcium, and were abolished when cells were bathed in an alkaline Ringer solution. Increasing intracellular calcium by photolysis of the caged calcium compound NP-EGTA also altered extracellular H+ flux. Immunocytochemical localization of the plasmalemma Ca2+–H+-ATPase (PMCA pump) revealed intense labelling within the outer plexiform layer and on isolated horizontal cells. Our results suggest that glutamate modulation of H+ flux arises from calcium entry into cells with subsequent activation of the plasmalemma Ca2+–H+-ATPase. These neurotransmitter-induced changes in extracellular pH have the potential to play a modulatory role in synaptic processing in the outer retina. However, our findings argue against the hypothesis that hydrogen ions released by horizontal cells normally act as the inhibitory feedback neurotransmitter onto photoreceptor synaptic terminals to create the surround portion of the centre-surround receptive fields of retinal neuron

Content analysis of on-package formula labelling in Great Britain: use of marketing messages on first infant, follow-on, growing-up and specialist formula

OBJECTIVE: To explore on-package formula messaging with reference to legislation and government issued guidance in Great Britain (GB). DESIGN: Formula products were identified, pictures of all sides of packs collated, and on-package text and images were coded. Compliance with both GB legislation and guidance issued by the Department of Health and Social Care (DHSC) was assessed. SETTING: All formula packs available for sale over the counter in GB between April and October 2020. PARTICIPANTS: Formula packs (n71) including infant formula, follow-on formula, growing-up formula and specialist formula were identified, coded and analysed. RESULTS: In total, 41% of formula packs included nutrition claims and 18% included health claims that may be considered non-permitted according to DHSC guidance. Additionally, 72% of products showed images considered 'non-permitted'. BMS legislation states infant and follow-on formula packs should be clearly distinguishable but does not provide criteria to assess similarity. Based on DHSC guidance, 72% of infant and follow-on formula packs were categorised as showing a high degree of similarity. Marketing practices not covered by current legislation were widespread, such as 94% of infant formula packs including advertisements for follow-on formula or growing-up formula. CONCLUSIONS: Text and images considered non-permitted according to DHSC guidance for implementing Breast Milk Substitute (BMS) legislation were widespread on formula products available in GB. As terms such as 'similarity' are not defined in BMS legislation it was unclear if breaches had occurred. Findings support the WHO call for loopholes in domestic legislation to be closed as a matter of urgency

Soil Modification as a Restoration Tool to Reduce Old World Bluestems in Texas Coastal Prairies

Nonnative Old World bluestem (OWB) grasses (e.g., Bothriochloas, Dichanthium spp.) have become dominant throughout the southern and central Great Plains, altering native plant communities and habitat quality for wildlife. Although conventional management strategies have not resulted in elimination or reduction of these grasses, modifying soil conditions to favor native plants may be an alternative restoration tool. We examined efficacy of 10 soil modification treatments (soil disturbance alone, pH increase, pH reduction, carbon addition, addition of soil mycorrhizae, and each combined with seeding of native vegetation) on 60 research plots at the Welder Wildlife Foundation Refuge in southern Texas in summer 2011. We sampled soil chemistry, vegetation density, cover, and height, and abundance of soil, terrestrial, and flying arthropods four and eight weeks after initial treatments. Severe drought prevented plant growth on treated plots and may have decreased the efficacy of soil treatments, especially pH reduction. As such, we compared vegetation and arthropod communities only between undisturbed plots dominated by native vegetation and dominated by OWBs. Species richness of vegetation was higher on plots dominated by native vegetation (4.4 species/m2, SE = 0.6) compared to plots dominated by OWBs (2 species/m2, SE = 0.5). Arthropods were more abundant in native vegetation (175 individuals/m2, SE = 4.1) relative to OWB-dominated plant communities (41, 1.3). Isopods and ants were the most abundant groups overall, although some of these taxa are nonnative. We will continue to collect data over the next two years to explore further soil modification as a restoration tool in grasslands impacted by OWBs

Decreased Plant and Arthropod Richness in Landscapes Dominated by Old World Bluestem Grasses: Implications for Wildlife

Old World bluestem grasses (OWBs, e.g., Bothriochloa, Dichanthium spp.) have become dominant throughout the southern and central Great Plains, altering native plant communities with concomitant effects for native wildlife. We examined plant and arthropod communities in areas dominated by native plants and areas dominated by OWBs at the Welder Wildlife Refuge in southern Texas. We sampled vegetation and arthropods on research plots (6 x 9-m, 5 each) every 4 weeks during summer 2011 and 2012. We found, on average, 2 (SE=0.2) more plant species, and 12-13 (SE=1.0) more arthropod species on native plant-dominated plots compared to OWB-dominated plots. Native plant-dominated plots also had 273 (SE=18.8) more individual arthropods in 2011, but 75 (SE=16.6) fewer than OWB-dominant plots in 2012, resulting from a population explosion and crash of woodlice in native plant-dominated plots. We recorded only 1 species of herbivorous arthropod from OWB-dominated plots in 2012; native plant-dominated plots had 5-6 (SE=0.68) additional herbivore species, suggesting that increased dominance by OWBs may create cascading effects on trophic dynamics. Because many species of wildlife depend on plants and arthropods for food, these changes in species richness and abundance suggest that restoration tools are required to reduce the competitive ability of OWBs. Traditional management strategies have not successfully reduced OWBs; as part of our research, we are modifying soil properties to attempt to provide novel management strategies for landowners to increase diversity of native species and habitat quality in grasslands impacted by OWBs