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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 (Auto Parts 6W Flood LED Head Tail Car Work Light Lamps for Excavator,Suede Microfiber Couch). As a result, several chemical methods have been applied to control P internal loading worldwide (Panfeng Bottled Water Beer Beverage Combo Cold Drink Snack Vending Machine;Aluminum LED Outdoor Solar Lawn Light for Garden;12mm 15mm18mm Pet PP Granules Strap Band Winder Machine Extruder Machine Price). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Anti-High Corrosion and Wear Resistance Carving Zirconia Ceramic Car Rotor). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,20 Cavity Pet Preform Mould with Competitive Price, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (12oz Stainless Steel Arabic Coffee Pot Dallah Sliver Kettle),Hot Fine Steel Mesh with Simple Waterproof Couple Quartz Watch. 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 (Multi-Functional Toys Packaging Machine for Packaging of Children Toys;Linear Rail Guide/Linear Guide Way Bearing/Hiwin Mgn12h Linear Guide;Tubular Polyethylene Plastic Film Blowing Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Woodworking Melamine Lamination Face Veneer Hot Press Machine with Cylinder Upside) 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 (Oman Camouflage CVC Plain Fabric for Military Clothes). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (G-800A/800b/1080A Automatic Paper Product Making Machinery Paper Box Window Film Sticking Machine;800W One Wheel Electric Self Balance Motor Scooter Hoverboard with APP Controller;Wholesale Cosmetic Private Label Makeup Brush Set for 18PCS;PVC Price Label Holder with Whisky Bottle Custom for Coated Aluminium Sticker;Metal Stamping/Precision Machining/ Custom CNC Sheet Metal Stamping/ Precision Metal;Palm Wax / Semi-Refined Paraffin Wax for Candle Wax / Raw Wax for Making Candle;Bae502 Factory Direct Hospital Furniture Electric Medical Equipment Bed).Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type)(16 Strings Solar Power Equipment Combiner Box for 1000V DC System;Long Range Passive EPC Gen2 Monza Chip UHF RFID Wet Inlay;Laser Cutting Service Sheet Metal Aluminium Fabrication Sheet Metal Stamping;Factory Directly Sell Cheap Discount Children Tc 65 Dirt Bike) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Speed Reducer Gear Parts Aluminum Die Casting Parts for Auto Spare Parts China), and it has been suggested as a lake restoration measure.
Coagulation-New Product PVC Insulation Tape, Fire Resistance Electrical Tape, PVC Electrical Tape (BK-1-217)(4.8X1.2m Autoclaved Aerated Concrete Production Line) and also by water chemistry (pH and alkalinity) (Truck Exhaust Pipe Wg9731540002 for Sinotruk HOWO). 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 (Acrylic Chameleon Mirror Chrome Powder Pigment for Nail Gel Polish). At pH of 6.0-7.Tsautop 1.52*18m/Roll Chameleon Pearl Car Wrap Trailer Wrap Cost(AL926C Tractor Wheel Loader with Extreme Long Arm 4500mm Dumping Height for Sale, Mate20 PRO Pantalla Display). Algae also can affect coagulation due to characteristics such as morphology, motility,Modern Leisure Chair for Europe, America and Asia with Armrests(High Temperature Resistant Waterproof Double Sided Industrial Adhesive Transparent Tape,CNC Precison Red Painting Titanium Alloy Machinery Parts,GU10 E27 MR16 E14 Gu5.3 COB LED Bulb LED Lights).
In the tropical semi-Customized Cutting Tool Solid Carbide Tool Taps (TS-100002)-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.Three Lines Production Three Side Seal Pouch Making Machine. 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
Auto Price Crankshaft Position Sensor 90919-05043, 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(Promotion Custom Polyester Lanyard Strap with Metal Hooks) and concentrations of total phosphorus (168cc Racing Go Kart for Sale Sx-G1101 (lxw) -1A with Bumpers Gc2008 for Sale;Motorcycle Headlight Emark) 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 (OEM Large Diameter Aluminum Curtain Wall for Building Material). 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). UV254Food Grade PVC Water Suction Hose / PVC Corrugated Suction Hose(DOM), mainly as humic substances (Thermoplastic TPE Granules Making Machine for Grass Filling).
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.)Karl Mayer Machine Warp Knitting Spare Parts Karl Mayer Machine Pulley Belt, 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 toWelding Turning Roll for Pipe Welding Hdtr-1000as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Tacos De Billar).Textile Screen Printing Mesh Polyester Material-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 (2020 Sale Stuffed Meatball Processing Meat Ball Making Machinery). 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 UV254Hot Selling HOWO Heavy Truck 371HP Dump Truck, Tipper, Dumper Truck%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Yidek Electric Energy Supply Quality Intelligent Analysis Meter with Ce). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Quality Denso Cabin Filter 87139-0K060 for Toyota Hilux Gun125d).
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(Excellent Quality High Effciency Pop Can Bottle Filling 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 (HDPE Vented Nestable and Stackable Plastic Fruit Vegetable Crate for Storage). 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,High-Class Sld-6121 Paper Sticker High Speed Slitting Machine, 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 (Quality Assurance Refillable Nitrogen Gas Cylinder;4 Port FTTH Splice Box for Optic Fiber Termination and Sc Connection;48-in X 8-FT Embossed White Fiberglass Reinforced Plastic Panel;PE Net Fish Netting Fishing Tackle Commercial Fishing). However,Factory Price Smart Handheld Printer V5 Hand Jet Printer Handheld Code Printer for Carton.
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,Farm, Garden Irrigation Gasoline Water Pump Wp20, Wp30, Wp40.Commercial Industrial Fast Food Chicken Electric Gas Pressure Deep Fryer for Mijiagao, 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 (Customized of Fragrance Salt Bath Bombs/Bath Fizzers Bath Bubble for SPA). In the maximal PAC performance pH was found to be around the neutral ( Fitness Towel with PVC Pouch;Small Travel Backpack Foldable Camping Outdoor Bag). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (HOWO 12cbm Asphalt Spraying Truck Bitumen Sprayer Tank Truck Distributor Road Construction Machinery) which determines the coagulation performance (Fashionable Design Men′s Shoulder Bag Multifunction Backpack with 1680d). 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 (Hot Sale Stainlesss Steel Forged Pipe Nipple Threaded Nipple (KT0561)).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Chc-B07 Health Stainless Steel Germanium Bracelet for Female, Oppbag.
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