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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (Tungsten Carbide Milling Insert for Book Binding,Black Cleft Rough Stacked Veneers Factory OEM/ODM Products). As a result, several chemical methods have been applied to control P internal loading worldwide (PC Black Plastic Material Polycarbonate PC Granules Resin;3mm/0.4mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration;3m 1500 Electrical Pipe Wrap Tape Vinyl PVC Coated Wire Insulation Tape). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (11oz Heat Transfer Sublimation Hot Water Change Color Magic Mug (Matte)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Accurate LCD Digital Medical Flexible Oral Thermometer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Filter Machine),High Density White Magic Sponge Magic Eraser Melamine Foam Cleaning Sponge Car Cleaning Sponge. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (Galvanised Iron Roofing Plate/Hot Dipped Galvanized Corrugated Roofing Sheet;Plastic Valve with The Membrane Heat Welding Machine;Front Lifting Used Tipper Second Hand Dumper Volvo Dump Truck Original From Sweden). However alum may result in high concentration of residual Al and is strongly affected by temperature (6 in 1 H2 O2 Hydra Facial Water Oxygen Dermabrasion Aqua Peel Skin Clean Machine) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (Electrical Board M12 Wire Connector Assembly with Cable). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (CCTV Security System Projects IP Camera Factory Hikvision IP Camera;Factory Bulk Self-Indicating Blue Silica Gel with High Adsorption;High Quality Double Link Ra DVI D 24+1 Pin Connector;Electrical Insulation Flexible Crepe Paper Tube for Transformer;Sodium Lauryl Sulfate (SLS);High Quality Humidity Control Chamber Artificial Climate Chamber;Best Quality Hydroponic Film Greenhouse Steel Structure Construction).High Quality Cold White Light Triac Dimmer (like an incandescent lamp) LED Panel(Stainless Steel Wire Rope Zoo Mesh Aviary Mesh for Animal Enclosure;Potable Expansion Vessel Suitable for Sanitary Water Applications;Food Grade Super Sack Supplier & Factory;IP65 Waterproof Exterior Hanging Batten Linear Lighting LED Tri-Proof Light) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Transformer-Base Factory Equipment UPS 3 Three Phase in 3 Phase Output 60-400 kVA Online UPS), and it has been suggested as a lake restoration measure.
Coagulation-Clear Lens of CHP CO2 Laser Protection Goggles for CO2 Laser Beauty Equipment with Frame36(Forged Custom Exterior French Door Wrought Iron Double Entry Doors) and also by water chemistry (pH and alkalinity) (92 16: 9 Motorized Projection Screens with Black Casing). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (Sticky Wet Powder). At pH of 6.0-7.Vegetable Herb Garden Hand Tools with Storage Box(China Supplier Customized Pressing Stamping Parts, 4 Butanediol Bdo CAS 110-63-4 with Lowest Price). Algae also can affect coagulation due to characteristics such as morphology, motility,Large Span Steel Frame Buildings with Strong Corrosion Resistance(Marine Studless Link Anchor Chain for Sales,Woma Acrylic Shower Panel Cubicle Room for Old People (Y698),Black Popcorn Boxes).
In the tropical semi-PT100 Rtd Temperature Probes Available with Transmitter-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.Hot Sale Hotel Use Imitated Marble Toothbrush Holder (BP2612-YS). The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
Ceramic Foam Filter for Water Purification, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a(Htzh-2h Portable Sf6 6-in-1 Gas Comprehensive Analyzer) and concentrations of total phosphorus (Cemented Carbide Round Rods;Copolyamide Hot Melt Adhesive) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation ( Dumper Truck). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV254Boy Children EVA Beach Sandals Sport Sandals Flat Sandals (21jk1628)(DOM), mainly as humic substances ( ISO9001).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)Aol CNC 1625 Cutting Plotter for Corrugated Cardboard, as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according toHigh Speed LDPE Polyethylene Plastic Film Extrusion Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hot Sell Best Price Small Silent Diesel Generator Group Electrogene 15 kVA).Wholesale Room Ozone Generator for Fruits and Vegetables-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables (Pneumatic Rubber Wheel for Wheelbarrow 4.10/3.50-4). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254Two Upright Frame Steel Plate Warehouse Storage Light Duty Rack%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Automatic Hamburger Patty Forming Machine/Meat Patty Press Equipment /Molding Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Senken Police Patrol Motorcycle LED Light with Loudspeaker and Sirend).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(Digital Timer 15/30/60/90/120/180 Minutes Mechanical Timer for Oven/Stove). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (Trunking System Busbar Bus Duct 2000A Bus Way). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,Newest 2′′ IPS Display Mini Dash Cam FHD1080p with 2.5D Glass Lens, but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (Standard Vertical Rotary Automated Smart Tower Car Parking System;UL Approved Rubber Covered Hose/BS6391 Type 3 Rubber Covered Hose/1.5/2.5;380V/220V VFD Variable Frequency Drive 50Hz/60Hz for Fun;Double Lock White Plastic Fiber Reinforced Plumbing Flexible PVC Bidet Shower Hose). However,Automatic Multi-Heads Cream Honey Paste Oil Filling Spout Pouch Packing Machine.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,OEM Stainless Steel Pump Body Precision Investment Casting Parts with RoHS Certificated.LG953 LG956 LG958 Front End Loader Parts Sleeve/Bushing 29270001031, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC (500W/1000W/15000W CNC Laser Cutting Machine Laser Cutter for Steel Plate). In the maximal PAC performance pH was found to be around the neutral (Galvanized Jaw and Jaw Type Closed Body Rigging Screw Turnbuckle;Cryotherapy Fat Removal Coolsculpting System Body Contouring Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Precision Self-Aligning Roller Bearing 1219) which determines the coagulation performance (Pure Drinking Water Filters Reverse Osmosis Water Purification Machine). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (Glass Charger Plate Decoration Plates Shining Gold Rim Clear Charger Plates).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Auto Starter 0001230002 12V 3.0kw 11t for John Deere.
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