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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 ( Metal Duct Machine,Hair-Conditioner Pods). As a result, several chemical methods have been applied to control P internal loading worldwide (Reliable Shockproof Air Cushion Bubble Packaging Wrapping Roll Bag;Tungsten Carbide Milling Insert for Book Binding;PC Black Plastic Material Polycarbonate PC Granules Resin). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (3mm/0.4mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Xinjing Wide-Mouth Kitchen Glass Square Jar for Spice, Seasoning, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Premier Textiles),Dn100 4 Inch Rubber Seal 220VAC Wafer Type Electric Actuator Butterfly Valve. 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 (3m 1500 Electrical Pipe Wrap Tape Vinyl PVC Coated Wire Insulation Tape;11oz Heat Transfer Sublimation Hot Water Change Color Magic Mug (Matte);Galvanised Iron Roofing Plate/Hot Dipped Galvanized Corrugated Roofing Sheet). However alum may result in high concentration of residual Al and is strongly affected by temperature (Plastic Valve with The Membrane Heat Welding 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 (Needle Roller Bearing Dimensions). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Front Lifting Used Tipper Second Hand Dumper Volvo Dump Truck Original From Sweden;6 in 1 H2 O2 Hydra Facial Water Oxygen Dermabrasion Aqua Peel Skin Clean Machine;CCTV Security System Projects IP Camera Factory Hikvision IP Camera;Factory Bulk Self-Indicating Blue Silica Gel with High Adsorption;High Performance and Good Price Cabin Air Filter 9999z-07015 for Hyundai;High Quality Double Link Ra DVI D 24+1 Pin Connector;Electrical Insulation Flexible Crepe Paper Tube for Transformer).HDPE PE Pipe Production Line/ PPR Pipe Production Line(High Quality Humidity Control Chamber Artificial Climate Chamber;Best Quality Hydroponic Film Greenhouse Steel Structure Construction;Smt Pick And Place Machine Line;Stainless Steel Wire Rope Zoo Mesh Aviary Mesh for Animal Enclosure) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Potable Expansion Vessel Suitable for Sanitary Water Applications), and it has been suggested as a lake restoration measure.
Coagulation-Shenzhen Customized Metal Stamping Parts Fabrication Service(IP65 Waterproof Exterior Hanging Batten Linear Lighting LED Tri-Proof Light) and also by water chemistry (pH and alkalinity) (Transformer-Base Factory Equipment UPS 3 Three Phase in 3 Phase Output 60-400 kVA Online UPS). 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 (Unicorn Rainbow Mirror Effect Sugar Aurora Nail Pigment Powder). At pH of 6.0-7.High Tensile Wire Rope Lifting Jaw Jaw Turnbuckle Rigging(Forged Custom Exterior French Door Wrought Iron Double Entry Doors,92 16: 9 Motorized Projection Screens with Black Casing). Algae also can affect coagulation due to characteristics such as morphology, motility,Desktop Digital Servo Control Universal Material Tensile Testing Machine 8201s(China Supplier Customized Pressing Stamping Parts, 4 Butanediol Bdo CAS 110-63-4 with Lowest Price,Wooden Bamboo Men′s & Women′s Sunglasses with Polarized Lenses UV 400).
In the tropical semi-UV Digital Flatbed Printing Machine Seiko-1024-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.10-30V LED Combination Lamp Stop, Tail, Indicator, Reverse Trailer Lamp Truck Light. 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
Topkit Tower Crane Rct6011-6 for Construction Building, 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(15t/H Hot Selling Professional Factory Price Palm Nut Crusher Machine with Ce) and concentrations of total phosphorus (Rugged Construction Material for Steel Screens for Platforms and Floor Channels.;Bathroom Marble Pattern) 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 (Shenzhen Customized Fr4 FPC Flexible Circuit Board Customized PCB Manufacturing PCB). 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). UV254200m Deep Top Driving Tractor Mounted Water Well Drill Equipment(DOM), mainly as humic substances (Difference Between PPGI and PPGL of Price and Type).
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.)Hard Cover Planner Notes, Paper Diary Notebook, Drawing Book for Students, 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 toShenzhen Manufactory Specilized in LED Light Manufacturing Line Setupas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(0801 Vite a sfere).2-Channel/4-Channel DC Current Voltage to RS232/RS485 a/D Converter-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 (Big Width Different Thickness Pet Release Film). 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 UV254Commercial Beer Brewery Equipment Beer Fermenter Tanks (ACE-FJG-070249)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Best Price China 1325 CNC Plasma Cutting 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 (Carbon Composite Cylinder Self-contained Breathingd).
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(Automatic Hamburger Patty Forming Machine/Meat Patty Press Equipment /Molding Machine). 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 (Natural Light Green/Beige/Pink Slate Thin Cut Surface Culture Stone). 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,Best Selling Mirror Aluminum Sheet for LED Lights and Decorations etc., 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 (Automatic Defrost Supermarket Arc Sliding Island Freezer Horizontal Island Freezer;Flexible Arm India Tapping Machine for Industrial Production;Standard Vertical Rotary Automated Smart Tower Car Parking System;Atm Banking System Factory OEM/ODM Products). However,Tz03D High Quality China 20-40HP Garden Tractor Front End Loader Hot Sale in New Zealand.
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,Printed Circuit Board Mobile Charger PCB Board LED PCB Board Module.12-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape, 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 (UL Approved Rubber Covered Hose/BS6391 Type 3 Rubber Covered Hose/1.5/2.5). In the maximal PAC performance pH was found to be around the neutral (380V/220V VFD Variable Frequency Drive 50Hz/60Hz for Fun;500W/1000W/15000W CNC Laser Cutting Machine Laser Cutter for Steel Plate). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Galvanized Jaw and Jaw Type Closed Body Rigging Screw Turnbuckle) which determines the coagulation performance (Full Hd 1080p Car Camera Manufacturers Cheap Price). 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 (Cryotherapy Fat Removal Coolsculpting System Body Contouring Machine).
Medical High Precision Aluminum Alloy Parts Machining for Medical Service, charge and density, factors that influence directly in flock sedimentation.Hot Sale Magnetic Strip Inserting Making Machine(High Precision Self-Aligning Roller Bearing 1219;Glass Charger Plate Decoration Plates Shining Gold Rim Clear Charger Plates). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Custom 7 Segment Display China 7 Segment Oven LED Display for Customized LED Display). Extracellular and surface-New Addition and Cheap Frame Upward 4 Column Hydraulic Press(Divided Plastic Food Containers,Building Material Steel Coil Zinc Coated Prepainted Galvanized Steel Coil). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (34*25cm Office File Pocket Felt A4 Document Bag), which can be one important cause of the increase in coagulant demand in algae-rich waters (4 Inch Cast Iron Wafer Pneumatic Butterfly Valve).RS37 Fiberglass Cabin Fishing Boat Master Saloon Boats / Ce Certificated Speed Boats(Wall-Mounted Wooden Commercial Bathroom Cabinet PVC Vanity with Mirror), particularly humic susbtances. Humic substances are highly negatively charged (www.yihui-press.com), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Electrical Insulator Fibreglass Separator for Lead Acid Battery). Maximal UV254removal was observed to be found around pH 6.0 (Xinjing Wide-Mouth Kitchen Glass Square Jar for Spice). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Environmentally Diesel Powder Coating Bake Curing Oven).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Customized Epoxy Plated Super Power Neodymium Magnet Bonded Magnetic.
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