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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 (DIY Modern Metal Wine Bottle Rack Organizer,Foldable Plastic Vegetable Fruit Egg Crate). As a result, several chemical methods have been applied to control P internal loading worldwide (Circular Magnetic Lifter for Steel Scrap Lifting MW5 - 70L/1;3-Wheel Motorcycle with 1500W Motor and EEC Certificate;10/30/50ml Single Gourd Shape Amber Essential Oil Cosmetic Glass Dropper Bottle for Mushroom). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hot Sale Vibration Equipment Gear Mootor Vertical Vibrator Motor). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Amazon Hot Sale Gym Towel, Fitness Towel with PVC Pouch, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Power Transformers),Precision CNC Auto Spare Machinery Parts for Car-Mounted Mobile Power Bank. 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 (Patient Modular Monitor with Wireless Network and Wire Network;25nm Ys-2.5b1 for Unreeling Hollow Shaft Magnetic Powder Brake;Medical Infusion Pump for Human and Veterinary with Fluid Warmer). However alum may result in high concentration of residual Al and is strongly affected by temperature (Ce Certificated Acm-60 PTFE Powder Grinding Mill) 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 (Coupler for Prestressing Screw Bar of Dia 25mm). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Buildings Materials ASA PVC Roof Tile Roofing Sheet;Cigar Tobacco Foil Ziplock Bags Custom Blunt Wraps for Medical Cannabis Packaging;Front Maintenance Outdoor Full Color P8 LED Display (P8 LED Video wall);Auto Crane Electrical Overhead Cable with Steel Wire;Dangle Belly Piercing;Two or Three-Tier Stainless Steel or ABS Medical Nursing Treatment Trolley with Wheels Px801;Water Microdermabrasion Hydro Facial Machine for Acne Removal Skin Revitalizer).Factory Price BV Designer Handbag Genuine Leather Women Purses Real Leather Ladies Handbags(Reflecting Aluminum Film Vacuum Evaporation Coating Equipment;5mm Wall Mounted Hotel LED Lighted Bathroom Mirror;Wholesale High Quality Personalized Hotel Slippers;Wholesale Compression Mesh Women Fitness High Waisted Seamless Leggings) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (China Products/Suppliers. China Wholesale Crystal Liquor Bottle with Frosting and Decal), and it has been suggested as a lake restoration measure.
Coagulation-Tsudakoma Zax-N Air Jet Looms Year 2007 210 Cm 2861 Dobby Weaving Textile Machinery(Airstream Mobile Food Truck Trailer/ BBQ Food Caravan/ Beverage Cart) and also by water chemistry (pH and alkalinity) (Die Casting Injection Molding Parts Deburring Deflashing Vibratory Barreling Machine). 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 (Rcm Concrete Chloride Migration Testing System). At pH of 6.0-7.5mm Wall Mounted Hotel LED Lighted Bathroom Mirror(Foil Induction Sealing Machine for Glass Plastic Bottle Jar,Popular Colorful Fiberglass Roof Tile / Bitumen Shingles Building Materials). Algae also can affect coagulation due to characteristics such as morphology, motility,Best 1.75mm 3mm ABS PLA 3D Printer Filament Supplier 1kg 5kg for 3D Printing Clear ABS Filament(3D Silver Reflective Custom Heat Transfer Label Garment Label,Warm Leather Glove Mink Fur Glove/Leather Palm Rabbit Fur Glove,New Simple Metal Sunglasses).
In the tropical semi-China Wholesale Hot Sale Microfiber Car Cleaning Towel-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.530ml Glass Drinking Water Bottle with Silicone Sleeve&Handle Lid. 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
Cylinder Borosilicate Glass Cooking Oil Bottle with Spout, 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(Best Face Injektions Hyaluron Hyaluronic Acid Dermal Fillers Cheek Fillers) and concentrations of total phosphorus (Factory Price BV Designer Handbag Genuine Leather Women Purses Real Leather Ladies Handbags;Color Laser Marking On Metal) 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 (100% Virgin Material PMMA Cast Acrylic Sign Board). 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). UV25411oz Heat Transfer Sublimation Hot Water Change Color Magic Mug (Matte)(DOM), mainly as humic substances (JL 155cm Life-Size Real Perfect Asian Shemale Sex Doll Torso for Man).
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.)Hot Selling SAA Rcm Listed CCT Changeable LED Down Light, 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 toHeat Insulation and Fireproof Composite Sandwich Wall Panelas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Competitive Square Flat LED Panel Lamp 300X300mm).Ferrous Sulphate Heptahydrate for Water Treatment-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 (Carbon Fiber Composite Autoclave Pressure Vessel for Sale). 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 UV254Factory Made Pneumatic Adjustable Gas Piston 600n for Garden Chair%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Standard Sizes Aluminium Galvanized Mild Steel U Channel). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Metal Folding Chairsd).
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(High Elastic Nylon Breathable Arm Elbow Sleeve for Sports). 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 (Silicone Hand Pipe Hand Tobacco Pipes Smoking Pipe with Glass Bowl). 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,NF3, Nitrogen Trifluoride, Liquid Gas, 99.99~99.999%, 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 (28dBi 1575.42MHz BNC Connector Active GPS Antenna;Electric Vehicle Brushless DC Motor 3kw 1500rpm 48V;Fully Automatic Frozen French Fries Making Machinery Manufacturer Price;Din931 Carbon Steel Hex Head Bolt). However,Recoil Steel Hot Coiled Extension Coil Compression Heavy Duty Spring.
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,Colorful Commercial PVC Vinyl Flooring for Office.Microblading Supplies Private Label Disposable Tattoo Pen Eyebrow Manual Pen with Blades, 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 ( Product Label). In the maximal PAC performance pH was found to be around the neutral (China Supplier Fresh Milk Tank Delivery Truck for Farm Use;Manufacturers Prefabricated Construction Steel Structure Space Frame Used Warehouse Buildings). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (DC 12V 24V Mini Portable Camping Car Freezer for Car) which determines the coagulation performance (High Quality Women Leggings Fitness Bra Gym Wear). 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 (30L 600W Dental / Lab Ultrasonic Cleaner Washer Ultrasound Cleaning Machines).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Construction Equipment 1.5 Cube Materials Portable Concrete Mixer.
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