Home About us Contact
|
Home About us Contact | ||
|
|
||
P Removal (p + removal)
Selected AbstractsImpact of Phosphorus from Dairy Manure and Commercial Fertilizer on Perennial Grass Forage ProductionJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2003E. A. Mikhailova Abstract Increased recovery and recycling of manure phosphorus (P) by crops on dairy farms is needed to minimize environmental problems. The main objective of this study was to compare P utilization by orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinaceae Schreb.) from dairy manure or inorganic fertilizer. The study was conducted from 1994 to 2000 at the Cornell University Baker Farm, Willsboro, NY, on a somewhat poorly drained Kingsbury clay (very,fine, illitic, mesic Aeric Epiaqualfs). The design was a split-plot in a randomized complete block with two manure rates (16 800 and 33 600 kg ha,1) and one nitrogen (N) fertilizer rate (84 kg N ha,1 at spring greenup and 56 kg N ha,1 prior to each regrowth harvest) as the main plots and grass species as subplots replicated six times. Fertilizer P [Ca(H2PO4)2] was applied to the fertilizer treatment in 1995 and 1996 at 11 kg P ha,1 year,1. Orchardgrass P removal averaged 21 % higher than tall fescue P removal for the spring harvest, but orchardgrass averaged 24 % lower P removal than tall fescue removal for all regrowth harvests from 1995,99. Phosphorus herbage concentration in the fertilizer treatment was in the range of 1.9,2.7 g P kg,1 compared with 2.2,5.3 g P kg,1 in the manure treatments. Seasonal P removal ranged from as low as 9.2 kg P ha,1 to as high as 48.5 kg P ha,1. Morgan extractable soil P in the top 0,0.20 m remained high through 1999, with 29.1 kg P ha,1 at the highest manure rate in tall fescue compared with 8.4 kg P ha,1 measured in 1993 prior to the experiment. In 2000, soil P at the highest manure rate in tall fescue dropped to 10.1 kg P ha,1, following cessation of manure application in 1998. Intensively managed harvested orchardgrass and tall fescue have the potential to remove large quantities of manure P. [source] The beneficial role of intermediate clarification in a novel MBR based process for biological nitrogen and phosphorus removalJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2009MinGu Kim Abstract BACKGROUND: A novel membrane bioreactor (MBR) is described, employing an intermediate clarifier. Unlike the established function of a final clarifier in a conventional biological nutrient removal system, the role of an intermediate clarifier has rarely been studied. Thus, this work focused on explaining the fate of nutrients in the intermediate clarifier, as influenced by the hydraulic retention time (HRT) of the preceding anaerobic bioreactor. RESULTS: The system was tested with two different anaerobic/anoxic/aerobic biomass fractions of 0.25/0.25/0.5 (run 1) and 0.15/0.35/0.45 (run 2) using synthetic wastewater. The major findings of the study were that phosphorus (P) removal was affected by the role of the intermediate clarifier. In run 1, P was removed at a rate 0.16 g d,1 in the intermediate clarifier while in run 2, additional P was released at 0.49 g d,1. The nitrogen (N) removal efficiencies were 74 and 75% for runs 1 and 2 respectively, while P removal was 91 and 96%. P uptake by denitrifying phosphate accumulating organisms (DPAOs) accounted for 41,52% of the total uptake in the MBR. CONCLUSIONS: This study found that the intermediate clarifier assisted chemical oxygen demand (COD), N, and P removal. With respect to the fate of P, the intermediate clarifier functioned as an extended anaerobic zone when the HRT of the preceding anaerobic zone was insufficient for P release, and as a pre-anoxic zone when the anaerobic HRT was adequate for P release. Copyright © 2008 Society of Chemical Industry [source] Development of a mechanistic model for biological nutrient removal activated sludge systems and application to a full-scale WWTPAICHE JOURNAL, Issue 6 2010Bing-Jie Ni Abstract In wastewater treatment plants (WWTPs) the production of nitrite as an intermediate in the biological nutrient removal (BNR) process has been widely observed, but not been taken into account by most of the conventional activated sludge models yet. This work aims to develop a mechanistic mathematical model to evaluate the BNR process after resolving such a problem. A mathematical model is developed based on the Activated Sludge Model No.3 (ASM3) and the EAWAG Bio-P model with an incorporation of the two-step nitrification,denitrification, the anoxic P uptake, and the associated two-step denitrification by phosphorus accumulating organisms. The database used for simulations originates from a full-scale BNR municipal wastewater treatment plant. The influent wastewater composition is characterized using batch tests. Model predictions are compared with the measured concentrations of chemical oxygen demand (COD), NH -N, NO -N, NO -N, PO -P, and mixed liquid volatile suspended solids. Simulation results indicate that the calibrated model is capable of predicting the microbial growth, COD removal, nitrification and denitrification, as well as aerobic and anoxic P removal. Thus, this model can be used to evaluate and simulate full-scale BNR activated sludge WWTPs. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] THE ROLE OF PERIPHYTON IN PHOSPHORUS RETENTION IN SHALLOW FRESHWATER AQUATIC SYSTEMSJOURNAL OF PHYCOLOGY, Issue 5 2003Article first published online: 26 SEP 200, Walter K. Dodds Eutrophication caused by phosphorus (P) leads to water quality problems in aquatic systems, particularly freshwaters, worldwide. Processing of nutrients in shallow habitats removes P from water naturally and periphyton influences P removal from the water column in flowing waters and wetlands. Periphyton plays several roles in removing P from the water column, including P uptake and deposition, filtering particulate P from the water, and attenuating flow, which decreases advective transport of particulate and dissolved P from sediments. Furthermore, periphyton photosynthesis locally increases pH by up to 1 unit, which can lead to increased precipitation of calcium phosphate, concurrent deposition of carbonate-phosphate complexes, and long-term burial of P. Actively photosynthesizing periphyton can cause super-saturated O2 concentrations near the sediment surface encouraging deposition of metal phosphates. However, anoxia associated with periphyton respiration at night may offset this effect. Linking the small-scale functional role of periphyton to ecosystem-level P retention will require more detailed studies in a variety of ecosystems or large mesocosms. A case study from the Everglades illustrates the importance of considering the role of periphyton in P removal from wetlands. In general, periphyton tends to increase P retention and deposition. In pilot-scale constructed periphyton-dominated wetlands in South Florida, about half of the inflowing total P was removed. [source] Grass-Shrub Riparian Buffer Removal of Sediment, Phosphorus, and Nitrogen From Simulated Runoff,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 5 2007Kyle R. Mankin Abstract:, Riparian buffer forests and vegetative filter strips are widely recommended for improving surface water quality, but grass-shrub riparian buffer system (RBSs) are less well studied. The objective of this study was to assess the influence of buffer width and vegetation type on the key processes and overall reductions of total suspended solids (TSS), phosphorus (P), and nitrogen (N) from simulated runoff passed through established (7-year old) RBSs. Nine 1-m RBS plots, with three replicates of three vegetation types (all natural selection grasses, two-segment buffer with native grasses and plum shrub, and two-segment buffer with natural selection grasses and plum shrub) and widths ranging from 8.3 to 16.1 m, received simulated runoff having 4,433 mg/l TSS from on-site soil, 1.6 mg/l total P, and 20 mg/l total N. Flow-weighted samples were collected by using Runoff Sampling System (ROSS) units. The buffers were very efficient in removal of sediments, N, and P, with removal efficiencies strongly linked to infiltration. Mass and concentration reductions averaged 99.7% and 97.9% for TSS, 91.8% and 42.9% for total P, and 92.1% and 44.4% for total N. Infiltration alone could account for >75% of TSS removal, >90% of total P removal, and >90% of total N removal. Vegetation type induced significant differences in removal of TSS, total P, and total N. These results demonstrate that adequately designed and implemented grass-shrub buffers with widths of only 8 m provide for water quality improvement, particularly if adequate infiltration is achieved. [source] Impact of membrane solid,liquid separation on design of biological nutrient removal activated sludge systemsBIOTECHNOLOGY & BIOENGINEERING, Issue 6 2005M. Ramphao Abstract Installing membranes for solid,liquid separation into biological nutrient removal (BNR) activated sludge (AS) systems makes a profound difference not only in the design of the BNR system itself, but also in the design approach for the whole wastewater treatment plant (WWTP). In multizone BNR systems with membranes in the aerobic reactor and fixed volumes for the anaerobic, anoxic, and aerobic zones (i.e., fixed volume fractions), the mass fractions can be controlled (within a range) with the interreactor recycle ratios. This zone mass fraction flexibility is a significant advantage in membrane BNR systems over conventional BNR systems with SSTs, because it allows for changing of the mass fractions to optimize biological N and P removal in conformity with influent wastewater characteristics and the effluent N and P concentrations required. For PWWF/ADWF ratios in the upper range (fq , 2.0), aerobic mass fractions in the lower range (fmaer < 0.60), and high (usually raw) wastewater strengths, the indicated mode of operation of MBR BNR systems is as extended aeration WWTPs. Although the volume reduction compared with equivalent conventional BNR systems with secondary settling tanks is not as large (40% to 60%), the cost of the membranes can be offset against sludge thickening and stabilization costs. Moving from a flow-unbalanced raw wastewater system to a flow-balanced (fq = 1), low (usually settled) wastewater strength system can double the ADWF capacity of the biological reactor, but the design approach of the WWTP changes from extended aeration to include primary sludge stabilization. The cost of primary sludge treatment then has to be paid from the savings from the increased WWTP capacity. © 2005 Wiley Periodicals, Inc. [source] | |||||||||||||