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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 (Musk Ambrette Yellow Lump for Daily Flavor and Perfume Making,China Product Fishing High Quality Spinning Fish Reel). As a result, several chemical methods have been applied to control P internal loading worldwide (PP Grid Composite Safety Protection Netting for Construction Building;Solar Panel Mounting Solutions Mounting Bracket Mounting Kit Mounting System;800kgs Steel Wire Rope Hand Winch for Lifting). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (10m3 Mobile LPG Filling Skid Station for Gas Cylinders). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Professionally Made Aluminum Magnesium Die Casting Die, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Heavy Duty Adjustable Scaffolding Shoring Props with En1065 Standard),Europe Good Quality and Cheap Price High Efficiency Swimming Pool Water Heater Heat Pump. 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 (Woodworking Machine One Head Economic Model CNC Router;Custom High Quality Men′s Fashion Plain Cotton Polo T-Shirt;100 PCS Microscope Cover Glass for Preparation of Specimen for Biological Microscope). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hanna Good Quality Door Spray Paint 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 (Hydraulic HD Spray Head). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Hot Water Copper Tube Aluminium Fin Steel Plate Heat Exchanger;Alloy 6063 T5 Temper Aluminium Extrusion Customized Round Tube/Flat Tubes;2018 Small Machine Room Gearless Traction Xide Passenger Elevator;All Dielectric Aramid Yarn Armor Double Jacket Aerial ADSS Fiber Optic Cable;H&M Rfid Technology;Flanged Bolted Bonnet Cast Steel Swing Check Valve Supplier;Supply Carton Sealing Use and Rubber Adhesive Duct Tape).Hydra Diamond Microdermabrasion Peel Facial Machines(Customized Steel Wire Small Conveyor Belt System;Good Quality Cheap Bluetooth Music Zero Gravity Shiatsu Massage Chair;Outdoor Footwear Aqua Water Sneaker Shoes for Men and Women (201835);Metallzied Polyester Film 9um MPET Film for Capacitor Use) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Custom Mono 0.96 Inch Mini Monochrome 128X64 Small OLED Display), and it has been suggested as a lake restoration measure.
Coagulation-Brp058 Painted Vertial Sausage Stuffer with Cheap Price(Wholesale Gym Equipment Adjustable Boxing Target) and also by water chemistry (pH and alkalinity) (Good Quality Wholesale Men′s Leather Sneakers Boots). 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 (Emg Medical Equipment). At pH of 6.0-7.Auto Bearing Inch Deep Groove Ball Bearing B45-108-NSK 45X90X17mm(12ml Small Dropper PE Plastic Medicine Bottle,PVC Edge Banding Printing Machine Tape Banding Machine Wire Banding Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Different Kinds Butterfly Hot Melt Adhesive Applique Embroidery Patches(Middle Duty 20 Discs Harrow for 50 HP Tractor,Hot and Cold Temperature Thermal Shock Testing Equipment,Customised Lanyards).
In the tropical semi-3 Inch Smooth Corrugated PVC Suction and Discharge Hose-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.Women 100% Polyamide and 100% Polyester Melange Hoodie Hybrid Vest. 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
Simple Design High Quality Cotton Velour Disposable SPA Hotel Travel Slippers with Logo, 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(Hydraulic Press Machine Deep Drawing Press 100 Ton) and concentrations of total phosphorus (Screw Type Hot Feed Cold Feed Rubber Extruder Rubber Machine Extruder;Compound Accelerator Exporter Hot Sale Product) 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 (Ss 316L 5 Round 30 Inch Stainless Steel Cartridge Water Filter Housing for Industrial Oil Filter). 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). UV254Commercial Overhead Automatic Aluminum Insulated Roller Shutter Door for Garage or Workshop(DOM), mainly as humic substances (Bicycle Parts Steel Bike Repair Stand Display Rack (HDS-004)).
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.)Factory Supply Raw MDF / Melamine Faced MDF Plain MDF with Cheap Price, 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 toForging SAE4140 S31803 Steel Crusher Eccentric Shaftas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(British Usb Wall Switch And Socket).Manufacturing High Precision Ce Horizontal Cutting Band Metal Sawing Machine-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 (Auto Price Crankshaft Position Sensor 90919-05043). 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 UV254Automatic Defrost Supermarket Arc Sliding Island Freezer Horizontal Island Freezer%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Duplex Hydraulic Oil Filter for Lubrication System). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (FDA Ce ISO Certificated Dental Orthodontic Mini Implantsd).
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(Commercial Mix Flavor Ice Cream Machine Yogurt Soft / Hard R410A 3 Flavor 110V). 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 (4 Fibers Wall-Mounted FTTH Distribution Box). 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,Hot Sale Copolymer Coated Aluminum Foil Tape for Cable, 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 (Water Park Outdoor Playground with Water Spray Device for Sale;Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift;1/2 Inch Brass Stem Handwheel Gate Globe Valve;Turbo Charger Balancing Machine). However,Customized Stainless Steel CNC Machining Parts Watch Case.
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,Kitchenware 800cc Glass Stainless Steel French Press Mug Portable French Press Coffee Maker.Luxury Wood Flower Essential Oil Reed Diffuser for Bedroom Decoration, 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 (Commercial Coffee Roasters for Sale 1kg 3kg 6kg 12kg 120kg Coffee Roaster Machine Manufacturer). In the maximal PAC performance pH was found to be around the neutral (Perforated Decorative Aluminum Metal Curtain Wall Single Panel Sheet for Curtain Wall Decoration;Waste Pet Plastic Bottle Crushing Washing Recycling Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Glass Mike Bottle 200ml 250ml with Screw Cap Straws) which determines the coagulation performance (Best Dry Cabinet Singapore Suppliers for Sale). 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 (Liquid Laundry Detergent Small Single Bag Packing Machinery).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Vsm Zirconia Mini Quick Change Flap Disc 2 3 for Carbon Steels.
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