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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 (Customized Stainless Steel CNC Machining Parts Watch Case,Forland Dump Truck). As a result, several chemical methods have been applied to control P internal loading worldwide (Auto Parts 6W Flood LED Head Tail Car Work Light Lamps for Excavator;Panfeng Bottled Water Beer Beverage Combo Cold Drink Snack Vending Machine;Aluminum LED Outdoor Solar Lawn Light for Garden). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (12mm 15mm18mm Pet PP Granules Strap Band Winder Machine Extruder Machine Price). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Quality 11oz Bone China Color Change Mugs Sublimation Coating Mugs (Matte), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Pet Childproof and Tamper Proof 120ml Plastic Eliquid Dropper Bottle),Best Sea Shipping Ex Shenzhen/Guangzhou to Acajutla/San Salvador. 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 (Anti-High Corrosion and Wear Resistance Carving Zirconia Ceramic Car Rotor;Multi-Functional Toys Packaging Machine for Packaging of Children Toys;Linear Rail Guide/Linear Guide Way Bearing/Hiwin Mgn12h Linear Guide). However alum may result in high concentration of residual Al and is strongly affected by temperature (Tubular Polyethylene Plastic Film Blowing 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 (High Pressure Compressor Pipe Jet Washer Hose 5/16 Inch for Washing Car Factory Sale). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Woodworking Melamine Lamination Face Veneer Hot Press Machine with Cylinder Upside;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;Dz47-63s 4.5ka 3p 4A MCB Miniature Circuit Breaker with TUV CB Test Report Inmtro Approval;PVC Price Label Holder with Whisky Bottle Custom for Coated Aluminium Sticker;Palm Wax / Semi-Refined Paraffin Wax for Candle Wax / Raw Wax for Making Candle).Guard Rail Roll Forming Machine 2.0-4.0mm Thickness(Bae502 Factory Direct Hospital Furniture Electric Medical Equipment Bed;16 Strings Solar Power Equipment Combiner Box for 1000V DC System;General Design Commercial Use Classic Veneer Office Table Photos (FEC3921);Long Range Passive EPC Gen2 Monza Chip UHF RFID Wet Inlay) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Factory Directly Sell Cheap Discount Children Tc 65 Dirt Bike), and it has been suggested as a lake restoration measure.
Coagulation-Flexible Semiauto Cosmetics Bottles Adhersive Labels Sticker(Speed Reducer Gear Parts Aluminum Die Casting Parts for Auto Spare Parts China) and also by water chemistry (pH and alkalinity) (4.8X1.2m Autoclaved Aerated Concrete Production Line). 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 (Professional Sports Soccer Football Synthetic Grass with Ce). At pH of 6.0-7.Two Sides Grey Silicon Coated Fiberglass Waterproof Roofing Fabric Cloth(Truck Exhaust Pipe Wg9731540002 for Sinotruk HOWO,AL926C Tractor Wheel Loader with Extreme Long Arm 4500mm Dumping Height for Sale). Algae also can affect coagulation due to characteristics such as morphology, motility,ANSI B16.5 Stainless Steel SS316 Forging Blind Flange( Mate20 PRO Pantalla Display,High Temperature Resistant Waterproof Double Sided Industrial Adhesive Transparent Tape,FDA Approved Disposable Biodegradable Foam Packaging Boxes for Fast Food).
In the tropical semi-Ss 316 304 Stainless Steel Water Tank with Steel Frame-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.Coms Camera Factory Vari-Focal Lens DVR Camera Web Camera Bullet. 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
1000bar Electric Water Cleaner Pump High Pressure Cleaner Pump, 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(Miniature Bearing 1*3*1mm 681 Zz NSK NTN SKF Bearings (W681/1R)) and concentrations of total phosphorus (Promotion Custom Polyester Lanyard Strap with Metal Hooks;Hollywood Style Led Vanity Mirror Lights) 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 (Custom Made Personalized Mini Pop Can Filling Machine). 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). UV254High Accurate LCD Digital Medical Flexible Oral Thermometer(DOM), mainly as humic substances (OEM Large Diameter Aluminum Curtain Wall for Building Material).
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.)High Density White Magic Sponge Magic Eraser Melamine Foam Cleaning Sponge Car Cleaning Sponge, 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 toPortable Solar Lantern with Built-in Solar Panelas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Ac Servo Motor).High Quality Cold White Light Triac Dimmer (like an incandescent lamp) LED Panel-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 ( Cargo Box). 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 UV254Clear Lens of CHP CO2 Laser Protection Goggles for CO2 Laser Beauty Equipment with Frame36%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (2020 Sale Stuffed Meatball Processing Meat Ball Making Machinery). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (19- Inch Floor Standing Internet Touch Screen Advertising Display Kioskd).
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(Durable Use for Clothes PU Synthetic Leather for Garment Eco-Friendly PU Synthetic Leather). 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 (Excellent Quality High Effciency Pop Can Bottle Filling Machine). 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,Vegetable Herb Garden Hand Tools with Storage Box, 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 (Electric Hand Circular Saw for Wood Cutting 185mm;Quality Assurance Refillable Nitrogen Gas Cylinder;4 Port FTTH Splice Box for Optic Fiber Termination and Sc Connection;Food Digital Thermometer). However,Large Span Steel Frame Buildings with Strong Corrosion Resistance.
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,PT100 Rtd Temperature Probes Available with Transmitter.Hot Sale Hotel Use Imitated Marble Toothbrush Holder (BP2612-YS), 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 (48-in X 8-FT Embossed White Fiberglass Reinforced Plastic Panel). In the maximal PAC performance pH was found to be around the neutral (Customized of Fragrance Salt Bath Bombs/Bath Fizzers Bath Bubble for SPA; Fitness Towel with PVC Pouch). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Small Travel Backpack Foldable Camping Outdoor Bag) which determines the coagulation performance (UPVC Pn10 DIN Equal Reducing Female Tee with Brass for Water Supply Fitting). 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 (HOWO 12cbm Asphalt Spraying Truck Bitumen Sprayer Tank Truck Distributor Road Construction Machinery).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Two Upright Frame Steel Plate Warehouse Storage Light Duty Rack.
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