Chemical Precipitation

A design of experiment (DoE) approach is presented for the optimization of Alendronate-hydroxyapatite nanoparticles� synthesis. The synthesis was performed using the chemical precipitation technique from calcium nitrate, diammonium hydrogen phosphate and alendronate. Synthesis temperature, reactant addition rate and ripening time were chosen as the most relevant experimental factors for our synthesis. Design of Experiments was used in order to measure these conclusive process parameters and their effect on controlling some final nanoparticles parameters, such us: alendronate incorporation efficiency (IncorporationEfficiency, %), hydroxyapatite crystallite size (Size_XRD, nm), hydroxyapatite particle size distribution (Size_DLS, �). Our study found that better HA-AL incorporation efficiency and small nonoparticles can be obtained using the following chemical process parameters: reaction temperature 30oC or smaller, ripening time 108h and addition rate 0.1mol/min. The analysis of more than one nanoparticles characteristics was possible using DoE software, MODDE 9.1. Thus, hydroxyapatite-alendronate incorporation efficiency should be expected to increase with decreasing temperature below 300C, increasing the maturate time at least 108h, at an addition rate of 0.1mol/min, in an N2 atmosphere. The same conditions will ensure nanoparticles small size that would be more desirable for the application of implants.

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Anaerobic Digestion of Primary Sludge Containing Iron Phosphate

Water Quality Research Journal ◽

10.2166/wqrj.1973.008 ◽

1973 ◽

Vol 8 (1) ◽

pp. 91-109 ◽

Cited By ~ 2

Author(s):

M.E. Jack ◽

G.J. Farquhar ◽

G.M. Cornwall

Keyword(s):

Anaerobic Digestion ◽

Phosphorus Removal ◽

Municipal Wastewater ◽

Iron Phosphate ◽

Chemical Precipitation ◽

Task Group ◽

Iron Compounds ◽

Primary Sludge ◽

Group Report ◽

Aluminum Compounds

Abstract The importance of phosphorus as a nutrient in the eutrophication of lakes and rivers has been well established (Fruh 1967). It has been shown in addition that a significant amount of this phosphorus arises from the discharge of treated and untreated municipal wastewater (Task Group Report 1967). Consequently, measures are being taken, notably in the Province of Ontario, for removal of phosphorus from wastewater by means of chemical precipitation. Chemicals exhibiting satisfactory phosphorus removal include lime, iron compounds and aluminum compounds (Leckie and Stumm 1970; Schmid 1968; Wuhrman 1968).

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Pre-Precipitation Facilitates Nitrogen Removal without Tank Expansion

Water Science & Technology ◽

10.2166/wst.1990.0233 ◽

1990 ◽

Vol 22 (7-8) ◽

pp. 85-92 ◽

Cited By ~ 2

Author(s):

Ingemar Karlsson ◽

Gunnar Smith

Keyword(s):

Waste Water ◽

Organic Matter ◽

Water Treatment ◽

Carbon Source ◽

Nitrogen Removal ◽

Waste Water Treatment ◽

Chemical Precipitation ◽

Sewage Water ◽

Laboratory Studies ◽

Denitrification Process

Chemically coagulated sewage water gives an effluent low in both suspended matter and organics. To use chemical precipitation as the first step in waste water treatment improves nitrification in the following biological stage. The precipitated sludge contains 75% of the organic matter in the sewage and can by hydrolysis be converted to readily degradable organic matter, which presents a valuable carbon source for the denitrification process. This paper will review experiences from full-scale applications as well as pilot-plant and laboratory studies.

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Operation Experiences with Biological Phosphorus Removal at the Sewage Treatment Plants of Berlin (West)

Water Science & Technology ◽

10.2166/wst.1991.0194 ◽

1991 ◽

Vol 24 (7) ◽

pp. 133-148 ◽

Cited By ~ 1

Author(s):

A. Peter ◽

F. Sarfert

Keyword(s):

Phosphorus Removal ◽

Sewage Treatment ◽

Chemical Precipitation ◽

Biological Phosphorus Removal ◽

Treatment Results ◽

Sewage Treatment Plants ◽

Research Activities ◽

Two Stages ◽

The Given ◽

Biological Phosphorus

In investigations concerning sludge bulking in Berlin enhanced biological phosphorus removal was first observed unexpectedly. Because since 1986 an officially preset limit of 2 mg TP/l must be kept in all Berlin wastewater discharges it was decided to explore the capabilities of the observed mechanism under the specific circumstances of the exciting two large treatment plants in Ruhleben (240,000 m3/d) and Marienfelde (100,000 m3/d). For this purpose some of the existing units at both plants were equipped with anaerobic zones which were generated mainly by process modifications. Additionally stage one of the Ruhleben plant was altered completely in order to investigate the combination of biological phosphorus and nitrogen removal as a special pilot study in three parallel trains. The research activities and treatment results gained in each of the two stages of the Ruhleben and in the Marienfelde plant are reported in detail. For example BOD-related phosphorus removal rates were obtained ranging from 2.3-4.5 mg TP per 100 mg BOD removed. It must be stressed that all examinations were performed on full-scale conditions. At present the given limit of 2 mg TP/l in the Ruhleben plant is met without any chemical precipitation at least on average. From the beginning biological phosphorus removal will be integrated into further projected extensions.

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Optimization of Nutrient Removal in Stockholm

Water Science & Technology ◽

10.2166/wst.1991.0191 ◽

1991 ◽

Vol 24 (7) ◽

pp. 103-111 ◽

Cited By ~ 1

Author(s):

G. Brattberg ◽

L.-G. Reinius ◽

M. Tendaj

Keyword(s):

Nutrient Removal ◽

Sewage Treatment ◽

Water Source ◽

Chemical Precipitation ◽

Phosphorus Load ◽

Sewage Treatment Plants ◽

Limiting Nutrient ◽

Baltic Proper ◽

Mechanical Stage ◽

The Baltic

Stockholm was founded at the point where the waters of Lake Mälaren emerge into the Baltic Sea. Lake Mälaren is the water source of the water works of Stockholm. The Lake also receives water from one of the sewage treatment plants. The outlet from the two other sewage treatment plants are in the inner part of the archipelago. During 1968-73 the treatment was improved, after which the phosphorus load to the receiving water significantly decreased. The total P concentration in the surface water has decreased since 1970 and phosphorus has replaced nitrogen as the most limiting nutrient throughout the entire archipelago within 50 km from Stockholm. To further reduce the eutrophication a continued reduction of the phosphorus load is most effective. For the Baltic proper as a whole, where primary nitrogen limitation is present, it is important to reduce the supply of nitrogen to the greatest possible extent. The treatment plants in Stockholm are located in subsurface rock-chambers. The treatment includes mechanical, biological and chemical treatment. In the mechanical stage the sewage is treated in screens, grit chambers and primary sedimentation. The biological stage is a conventional activated sludgeprocess. For the chemical precipitation ferroussulphateis added before the screens. The sludge is stabilized in anaerobic digesters and dewatered in centrifuges before disposal on farmland. To meet more stringent requirements on nitrification and nitrogen removal several projects are going on to optimize the nutrient removal. The aim of these investigations is to improve the plants' performance within the existing plant.

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Performance Stability of Small Biological Chemical Treatment Plants

Water Science & Technology ◽

10.2166/wst.1990.0212 ◽

1990 ◽

Vol 22 (3-4) ◽

pp. 275-282

Author(s):

R. Storhaug

Keyword(s):

Activated Sludge ◽

Chemical Treatment ◽

Chemical Precipitation ◽

Poor Quality ◽

Precipitation Process ◽

Chemical Plants ◽

Effluent Standards ◽

Main Portion ◽

Rotating Biological Contactors ◽

Number Of Treatment

Biological and chemical treatment plants constitute a main portion of the overall number of treatment plants in Norway. The biological and chemical plants are divided into three process groups, simultaneous precipitation and activated sludge, combined precipitation and rotating biological contactors (RBC) and post precipitation and activated sludge. Aluminium sulphate or ferric chloride are the commonly used flocculants in the chemical precipitation process. Effluent data from 174 Norwegian biological chemical treatment plants are evaluated. Compared to the effluent standards for each process group, post precipitation shows the best performance. On an average these plants have the lowest actual utilization of the design capacity. The most important factors that cause the treatment plants not to meet the effluent standards are, poor quality of the sewer system, improper design of the plant and organizational problems. Satisfactory separation of particles, flow equalization and proper operational management, are the basic demands to achieve low effluent concentrations for tot-P and BOD7.

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Use of lime for the upgrading of existing wastewater treatment systems

Water Science & Technology ◽

10.2166/wst.1994.0626 ◽

1994 ◽

Vol 29 (12) ◽

pp. 279-282 ◽

Cited By ~ 2

Author(s):

C. Güldner ◽

W. Hegemann ◽

N. Peschen ◽

K. Sölter

Keyword(s):

Large Scale ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Chemical Precipitation ◽

Fatty Acid Production ◽

German States ◽

Lime Solution ◽

First Results ◽

Pre Treatment

The integration of the chemical precipitation unit which would inject a lime solution into a series of mechanical-biological processes, including nitrification/denitrification, and the sludge treatment are the subject of this project. The essential target is the large-scale reconstruction of a mechanical-biological sewage treatment plant with insufficient cleaning performance in the new German states and the adjustment of the precipitation stage to the unsteady inflow of sewage. First results indicate that the pre-treatment performance could be improved by ≅ 20% and the discharge of concentrations of COD, BOD, N and P could be reduced and homogenized. In addition, experiments on hydrolysis and acidifiability of the pre-treatment sludge have been carried out on a laboratory level with the object of making sources of carbon readily available for denitrification. In the course of the experiment, inhibition of fatty acid production by calcareous primary sludge could not be detected. The characteristics of the sludge, such as draining and thickening were considerably improved by the adding of lime.

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Evaluation of Small Wastewater Treatment Plants in the County of Århus – Denmark

Water Science & Technology ◽

10.2166/wst.1993.0201 ◽

1993 ◽

Vol 28 (10) ◽

pp. 33-41

Author(s):

Jes la Cour Jansen ◽

Bodil Mose Pedersen ◽

Erik Moldt

Keyword(s):

Wastewater Treatment ◽

Constructed Wetlands ◽

Biological Treatment ◽

Wastewater Treatment Plants ◽

Chemical Precipitation ◽

Common Type ◽

Treatment Efficiency ◽

Effluent Quality ◽

Different Types

Influent and effluent data from about 120 small wastewater treatment plants (100 - 2000 PE) have been collected and processed. Seven different types of plants are represented. The effluent quality and the treatment efficiency have been evaluated. The most common type of plant is mechanical/biological treatment plants. Some of them are nitrifying and some are also extended for chemical precipitation of phosphorus. Constructed wetlands and biological sandfilters are also represented among the small wastewater treatment plants.

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Tuning the mechanical and dielectric properties of zinc incorporated hydroxyapatite

Current Nanoscience ◽

10.2174/1573413716666200313162039 ◽

2020 ◽

Vol 16 ◽

Author(s):

Alliya Qamar ◽

Rehana Zia ◽

Madeeha Riaz

Keyword(s):

Dielectric Constant ◽

Dielectric Properties ◽

Bone Growth ◽

Healing Process ◽

Secondary Phase ◽

Chemical Precipitation ◽

Hexagonal Structure ◽

Precipitation Method ◽

Low Frequencies ◽

A Minor

Background: Hydroxyapatite is similar to bone mineral in chemical composition, has good biocompatibility with host tissue and bone. Objective: This work aims to tailor the mechanical and dielectric properties of hydroxyapatite with zinc sudstitution, to improve wearability of implant and accelerate the healing process. Method: Pure and zinc incorporated hydroxyapatite Ca10(PO4)6(OH)2 samples have been successfully prepared by means of the chemical precipitation method. Results: The results showed that hydroxyapatite(Hap) having hexagonal structure was the major phase identified in all the samples. It was found that secondary phase of β-tricalcium phosphate (β-TCP) formed due to addition of Zinc resulting in biphasic structure BCP (Hap + β-TCP). A minor phase of ZnO also formed for higher concentration of Zn (Zn ≥ 2mol%) doping. It was found that the Zn incorporation to Hap enhanced both mechanical and dielectric properties without altering the bioactive properties. The microhardness increased upto 0.87 GPa for Zn concentration equal to 1.5mol%, which is comparable to the human bone ~0.3 - 0.9 GPa. The dielectric properties evaluated in the study showed that 1.5 mol% Zn doped hydroxyapatite had highest dielectric constant. Higher values of dielectric constant at low frequencies signifies its importance in healing processes and bone growth due to polarization of the material under the influence of electric field. Conclusion: Sample Z1.5 having 1.5 mol% Zn doping showed the most optimized properties suitable for bone regeneration applications.

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