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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 (Easy Fan Lashes Blooming Lashes Volume Eyelashes Extension,Office Track Lighting). As a result, several chemical methods have been applied to control P internal loading worldwide (Single Phase Frequency Inverter AC Motor Speed Controller 250000W;Medical Instrument Compression Leg Massage 8 Chamber Best-Selling in The Medical and Beauty Market;Dienedione Raw Powder Estra-4). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Modern 60W Glass Table Lamp for Office Bedroom Home Decor). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Mill Supplier Grey Board Cake Boards with Flower Edges with SGS (B&C-K074), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Construction Steel Structure Material for Shopping Center),J5 6-24V 27.8*46.6mm 10.64W DC Motor for Grass Cutter. 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 (High Quality Lift Gas Spring for Bed Support;Brp058 Painted Vertial Sausage Stuffer with Cheap Price;5FT2′ 157cm Female Premium Platinum Silicone Love Doll Lifelike Adult Love Sex Toy for Men). However alum may result in high concentration of residual Al and is strongly affected by temperature (Competitive Wholesale Price Nicotine Salt E Liquid Vgod Mango Bomb) 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 (Forged Ring). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (8.8ah;Custom Cheap Design Woven Patch Embroidery Badge;316L Stainless Steel Pipe Fitting Elbow SMS DIN Elbow;Multi Color Dual Slides Crayon Inflatable Bouncer Castle;Asymmetric Street Lights Road Lamp Anti Glare IP66;5053 Aluminum OEM ODM Computer Parts Oxide Anodized CNC Machining Mobile Phone Parts;Roller Shutter Components Galvanized Octagonal Tube Axle).Cross-Border Jewelry Hot Silver Set Diamond Full Diamond Crown(Waterproof Home Decoration Decoration Material WPC Spc Wall Panel;Competitive Prices Gypsum Board;Led Shoe Battery Strip;Factory Direct Sale Hotfix Laser Motif Customer Desgined for Decoration) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Quality Manufacturer Plastic PS Extruder Foam Sheet Extrusion Machine), and it has been suggested as a lake restoration measure.
Coagulation-PP Woven Bag/Sack for Rice/Flour/Food/Wheat 40kg/50kg/100kg, Pol.(Top Quality Gasoline Grass Trimmer Parts Nylon Head Blade) and also by water chemistry (pH and alkalinity) (Multi Spiral Vegetable Slicer Chopper Spiralizer Cutter for Home Use). 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 (Fecral Resistance Wire). At pH of 6.0-7.Jinfeng H Type Best Price Poultry Farm Egg Layer Chicken Cages(Eco-Friendly Biodegradable Natural Wheat Straw Toothbrush with Bamboo Charcoal Infused Bristles,New 11ml Nail Polish Bottle with Brush and Cap). Algae also can affect coagulation due to characteristics such as morphology, motility,High Speed Spiral Dough Mixers 50kg Flour for Bread(Cptau Series Pre Cu and Al Insulated Bimetallic Cable Lugs,LED Mounter Jx-300LED/ Chip Shooter/ Jx300LED Mounter,Adults Pvc/Polyester Watertight Jacket).
In the tropical semi-Qgd Series 3 Inch Deep-Well Submersible Electric Screw Water Pump-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.Ankle Support Brace Foot Guard Sport Injury Wrap Elastic Splint Strap Protect. 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
Universal Cable Fault Testing Instrument Tester / Analyzer, 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(10L Diesel/Fuel Injector Industrial Ultrasonic Cleaning Machine) and concentrations of total phosphorus (D09 Lightweight Foldable Lithium Battery Electric Wheelchair for Elderly People;High Quality Excavator Hydraulic Vibration Stone Breaker Vibro Ripper Attachment) 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 (Zero Spangle Gi Steel 2mm 1500mm Galvanized Iron Sheet Price). 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). UV2543600 Rpm Concrete Machinery Ride on Power Trowel Factory(DOM), mainly as humic substances (Soft Green Landscaping Grass Artificial Turf).
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.)20 Cavity Pet Preform Mould with Competitive 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 toNew Type High Pressure Italy Permanent Magnet Oil Free Screw Air Compressoras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Ptfe Carbon Tapes).Hot Fine Steel Mesh with Simple Waterproof Couple Quartz Watch-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 (Anti-Corrosion Galvanized Collated Drywall Screw Dry Wall Screws). 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 UV254Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Lab Pipette Tips with Good Quality Low Price). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Customize Rattan Sofad).
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(Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage). 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 (Single Color Twill Tapes Automatic Screen Printing Machine Supplier). 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,New Product PVC Insulation Tape, Fire Resistance Electrical Tape, PVC Electrical Tape (BK-1-217), 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 (Top Quality Cleaning Cloth Microfiber Hair Salon Towel;Ce Certification Jigging Machine for Manganese Ore Extraction/Manganese Ore Refining Machine;Weather Resistant Outdoor Rattan Wicker Aluminum Folding Reclining Beach Chair;Telescopic Handle Garden Hedge Pruning Trimming Scissor Shear). However,Tsautop 1.52*18m/Roll Chameleon Pearl Car Wrap Trailer Wrap Cost.
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,Modern Leisure Chair for Europe, America and Asia with Armrests.Customized Cutting Tool Solid Carbide Tool Taps (TS-100002), 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 (HPMC 200). In the maximal PAC performance pH was found to be around the neutral (Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump;210t Nylon Fabric Parachute Mosquito Net Hammock Beach Hammock). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Wholesale Baby Shoes Kids Boy Wear LED Flashing) which determines the coagulation performance (Full-Auto DIP PCBA Line Wave Soldering 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 (Low Price & High Quality Stainless Steel X-ray Lead Door).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Textile Screen Printing Mesh Polyester Material.
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