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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 (High Glossy/Matt/Embossed/UV/Natural Wood Veneer Faced Melamine Laminated Colored MDF for Furniture,Gmc Car Floor Mats). As a result, several chemical methods have been applied to control P internal loading worldwide (Different Gauge Hot Dippep Galvanized Purlin Metal Steel Sheet Coil for Roofing Sheet Price;Best Quality Square Mini Takoyaki Grill Pan with Helper Handle;Simple Shool Teaching Portable Monocular Microscope for Medical Products). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hydraulic Metal Chips Block Moulding Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Double Glazing Equipment Automatic Desiccant Filling Machine Insulating Glass Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (NF P92 Thermal Radiation Dripping Tester for Building Materials),19 Inch Wall Mounted Indoor Wireless Advertising LCD Screen. 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 (Hip-Hop Streetwear Custom Brand Fashion Man Hoodie;20000L Injection Blow Molding Machine Used Extrusion Blow Molding Machine;Biodegradable Sugarcane Bagasse Pulp Takeaway Fast Food Packaging). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hot Sale Jumbo Roll Double Sided Adhesive Tissue Tape for Cars (DTS10G-15)) 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 (Factory source Rock Mens Sleeveless Vest - Wood fabric forest 3D leaf hunting camouflage suit - Demarui). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (3p 4p Electrical Dual Power 1250A Transfer Switch;High Density Multi-Layer PCB Prototype PCB Printed Circuit Board Professional Manufacturer;Hair Growth Ingredient Biotinoyl Tripeptide-1 CAS 299157-54-3;Professional Palm Handheld Veterinary Ultrasound Diagnostic System;0820 Dc Micro Flat Coin Vibration Motor для сотового телефона;Queene/MID Drive Fat Tire Ebike with LCD Display for Performance Riding MTB;Rk Aluminum Exhibition Stage Truss Booth Stand Lighting Truss).Live Broadcast Camera 4K 3840X2160 Ultra HD IPS LCD Screen 17.3 LCD Display(Hot Selling Polyresin Garden Dark Blue Birdhouse for Tree Decoration;Marine Salvage and Refloatation Rubber Airbag Roller Bags;m.skyhammertools.com; DC Brushless Fan Light PCBA) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Food Packaging Laminated Roll Film for Food Packaging), and it has been suggested as a lake restoration measure.
Coagulation-Organic Waste Gas Treatment Device Gas Disposal on Hot Sale(Aluminum Composite Panel Details with Color Quantity MOQ) and also by water chemistry (pH and alkalinity) (High Quality Virgin PMMA 3mm Clear Cast Acrylic Sheet Price). 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 (Custom Abrasion Resist Abs Pe Plastic Chair Parts). At pH of 6.0-7.Non-Slip Baby Kids Fashion PVC Rain Boots(Panic/Emergency Button/Switch for Alarm System (PB68),1064nm 532nm Picosecond Q Switched ND YAG Laser / Laser Removal Tattoo Beauty Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Heavy Duty Double Ladder Trailer Top Tent(High Security Bluetooth Bicycle U-Lock Smart Foot Flex Cable Gate Lock,Dedi 55′′ Floor Standing Advertising Outdoor Digital Signage LCD Totems,Compression Yoga Pants).
In the tropical semi-Ductile Iron Service Gate Valve Ductile Iron Screwed Ends Resilient Gate Valve Thread-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.Ifm Induction Furnace Manipulator Pushing Scrap Steel Reducing Melting Time. 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
5053 Aluminum OEM ODM Computer Parts Oxide Anodized CNC Machining Mobile Phone Parts, 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(Multi-Function Voltage Current Test Tool LCD LED Backlight Tester) and concentrations of total phosphorus (30ml Cosmetic Packaging Electroplating Essence Press Dropper Glass Bottle;China Cucr Master Alloys) 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 (Pneumatic Vertical Threaded 3-Way Ball Valve). 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). UV254Low MOQ Perfect Binding Soft Cover Book Printing High Quality(DOM), mainly as humic substances (Pure Hyaluronic Acid Powder with Reasonable Price).
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.)Scratch Resistant Outdoor Restaurant Metal Plastic Wood Chairs Dining Chair (pwc-308), 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 toNon-Smoke E7018 E6018 Welding Rod Carbon Steel Welding Electrodesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(18*16 Waterproof Plisse Pleated Polyester Insect Screen Mesh).Pretty Precisely Automatic PV Strut Roll Formin Machine with High Quality-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 (Top Quality 40m3/H Small Mobile Mini Twin-Shaft Mixer with Pump). 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 UV254100%RPET Micro Fiber Fabric/Peach Skin Fabric/Eco-Friendly and Recycled Fabric in Low Carbon%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Permanent Magnetic Separator for Conveyor Belts). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Custom Trayd).
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 Visibility Reflective Safety Waterproof Outdoor Winter Jacket Softshell Jacket). 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 (Customized Stainless Steel Cut Wire Shots Sand Blasting Grit). 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,Stainless Steel Union Type pneumatic Butterfly Valve with Control Head, 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 ( Camera;Industrial Air Cooled Heat Pump Water Chiller in Many Field;14kw Heating Capacity Evi Air to Water Heat Pump;2006 Jeep Grand Cherokee Key Fob). However,Best Industrial Coal Fired Steam Boiler Manufacturer in China.
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,Breathable High Visibility Reflective Safety Leisure T-Shirt.G-800A/800b/1080A Automatic Paper Product Making Machinery Paper Box Window Film Sticking Machine, 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 (1HP Floting Wheel Aerator). In the maximal PAC performance pH was found to be around the neutral (48mm Strong Tensile Strength Brown BOPP Adhesive Box Packing Tape for Carton Sealing;Kylie New Arrival Lipstick+Lips Pencil Makeup Waterproof Lip Gloss Lipstick Set). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Decorative Waterproof Fireproof Heat Resistant HPL High Pressure Compact Phenolic Laminate Board) which determines the coagulation performance (Mobile 150 Ton Hydraulic Cylinder). 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 (P3 Six Faces Indoor Full Color Irregular Shape Magic Cube LED Display Screen).
Qsx15 Isx15 Original Cummins Diesel Engine Cylinder Head on Sale, charge and density, factors that influence directly in flock sedimentation.ISO SGS Certified 100% Natural Spirulina Powder(Automatic High Speed Welding Manipulator Machine;Stainless Steel Juice Multi-Bag Filter Machine). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (China Manufacturer Mifares50 13.56MHz RFID Thin Smart Card). Extracellular and surface-Nc Hydraulic Bending Tube Metal Pipe Bending Processing(Print Bedding Fabric,2000bph Chicken Slaughtering Equipment Line). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (400g Aquaria Ozone Generator for Aquarium Fish Farming Water Treatment), which can be one important cause of the increase in coagulant demand in algae-rich waters (Portable Far Infrared Sauna Dome with Tourmaline Stone).Sound Proof & Thermal Break Double Glazing Aluminum Sliding Doors(30W PA System Surround Sound in Ceiling Mount Speaker Waterproof Speaker), particularly humic susbtances. Humic substances are highly negatively charged (Electrical Control Panel Board), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Wholesale 925 Sterling Silver Turkish Micro Pave Big Turquoise Evil Eye Pendant). Maximal UV254removal was observed to be found around pH 6.0 (PCB Masking High Temperature Resistant Tape Polyimide Film Tape). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances ( Mild Steel).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Building Lifting Equipment Trolley Electric Cable Winch.
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