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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 (Quality Assured Large Freight Volume Fire Resistant Rubber Conveyor Belt,Mini 3 Folding Umbrella). As a result, several chemical methods have been applied to control P internal loading worldwide (Vci PE Film for Ferrous Metal with Anti-Rust Performance;Hot Sale Pig Farm Equipment Galvanized Farrowing Pens;Ethylene-Propylene-Diene Monomer Rubber Waterproof Materials). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Aluminum Running Boards Side Step for Ranger 2012+). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Medical High Precision Aluminum Alloy Parts Machining for Medical Service, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Automobile Model Making),Hot Sale Magnetic Strip Inserting Making Machine. 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 (Marine PVC Lining Durable Fire Hose Double Jacket Fire Hose;Magic Smart Bluetooth Illuminated Mirror Bathroom LED Mirror with Clock Display;Qsx15 Isx15 Original Cummins Diesel Engine Cylinder Head on Sale). However alum may result in high concentration of residual Al and is strongly affected by temperature (Concrete Stone Cutting Diamond Chain Saw on Sale) 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 Produce Custom Logo Embroidered Orange Cotton Terry Absorbent Baby Shoulder Bib). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Intelligent Auto Tracking Indoor Mini Camera Smart Life Tuya IP Camera;Stormwater Retain Dimple Plastic Board Roll Drainage Sheet;Bct-01 Hospital Furniture ABS Medical Emergency Treatment Trolley Cart;Factory HDI PCB Hole Blue Oil Immersion Gold with UL and RoHS;Agricultural Spraying Machine Mist Duster Boom Sprayer Farm Tractor;Customized High Performance Industrial Oil Hydraulic Cylinder for Metallurgical Industry;240L German High Capacity Shopping Trolley with Baby Seat).New Addition and Cheap Frame Upward 4 Column Hydraulic Press(1 2 3 4 5 6 8 10 12 14 16 18 20 24 26 Inch Pneumatic Flanged Valve with Actuator;Car Parts Thermostat Housing with 4-Pin Sensor for Renault;3 Layer Custom Logo 500ml Protein Shaker Bottle with Storage Compartments;Factory Wholesale Pillow Low Price Polyester Microfiber Down Alternative Cushion) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Strong and Durable Outdoor Wedding Furniture Resin Solid Wood Wimbledon Folding Chair), and it has been suggested as a lake restoration measure.
Coagulation-RS37 Fiberglass Cabin Fishing Boat Master Saloon Boats / Ce Certificated Speed Boats(ASTM A500 Grade a Mild Steel Material Shs Hollow Sections) and also by water chemistry (pH and alkalinity) (OEM Design 24 & 30 Cavities Cold Runner Spoon Mould). 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 (Camisola feita sob encomenda de Crewneck). At pH of 6.0-7.Customized Epoxy Plated Super Power Neodymium Magnet Bonded Magnetic(100% Cotton Heavy Duty Workwear Wholesale Work Clothes,High Speed Aluminum Alloy + ABS Shell Video Type-C to HDMI Cable). Algae also can affect coagulation due to characteristics such as morphology, motility,2017 Luxury Acrylic Double Jar White Jar for Cosmetic Packaging(Used Jam/Tomato/Chilli Pasty Manual Filling Machine with Sauce Material,24PCS Sunflower Waterproof Super Bright Battery LED Road Warning Lamp,China Manufacturers Cheap Cotton Duvet Cover).
In the tropical semi-Multipurpose Rutile Titanium Dioxide TiO2 Pigment-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.Polynaphthalene Sulfonate Naphthalene Based Superplasticizer Powder. 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
Cemented Carbide Round Rods, Tungsten Hard Alloy Carbide Rods, 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(Linyi Jianzhong Square Veneer Tube Dryer Wood Veneer Dryer Machine for Plywood) and concentrations of total phosphorus (High Precision CNC Milling Aluminum Case Electronic Spare Parts Custom Watch Housing;New Techniquel Hot Selling Two Side Sealingmotorcycle Inner Tube) 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 (Masturbators Adult Sex Toys Japanese Love Doll). 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). UV254Roll Forged Steel Sheaves for Crane Sheave Block(DOM), mainly as humic substances (Top Quality Poultry and Livestock Automatic Manure/Organic Fertilizer Composting System).
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.)Aluminum Composite Panel Details with Color Quantity MOQ, 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 to4 Drawer Steel Office Vertical Filing Cabinetas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Customized Arc Display Rack Retail Shop Gondola Shelving).Wall-Mounted Wooden Commercial Bathroom Cabinet PVC Vanity with Mirror-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 (Recyclable Bottle Bamboo Material 5ml Perfume Oil Packaging with Amber Glass Inner). 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 UV254China Supplier Iodine Crystals / Iodine Balls CAS 7553-56-2 with High Quality and Good Price%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Impulse Plastic Sprinkler Irrigation Traveling Lawn Sprinkler for Garden). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (2 3-Dimethyl-1-Butene Cas No 563-78-0d).
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(Metal Solar Powered Crab Shape Outdoor Garden Ornaments LED Solar Lighting). 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 (Electronic Home Refrigerator Freezer AC 110-230V Mini 12V Car Fridge). 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,Automatic Plastic and Glass Bottle Inductor Sealing 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 ( Motor Cable Wire Electrical Power Cable;Class 1 Foam Rubber Insulation Pipe for Air Conditioner;Sublimation Coated Aluminum Sheets for Heat Transfer Printing;Drymix Cement Industrial Horizontal Ribbon Mixer). However,High Speed Double Wall Corrugated Pipe Extruder, Drainage Pipe Machine.
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,China Construction Machinery Sheet Metal Parts Manufacturers CNC Auto Parts.Three Phase Fan Water Pump Electric Asynchronous Induction Motor, 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 (Solid Wood Countertop Wood Table Top Wood Island Top Wood Bar Top Wood Table Top). In the maximal PAC performance pH was found to be around the neutral (Ccaf Vertical Cartridge Dust Collection for Sand Blasting; Camping). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (GS-1612 Factory Direct Cheap Hot Sale Fabric/Acrylic/Wood/Granite CO2 Laser Cutting Engraving Machine) which determines the coagulation performance (Agricultural Grabs Wheel Loaders Manufacturers Cheap Price). 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 (Luxury Comfortable Mini Bread Spring Mattress in Bedroom Furniture).
Star Necklace Jewelry Wholesale Fashion 925 Sterling Silver Necklace Jewelry, charge and density, factors that influence directly in flock sedimentation.Competitive Wholesale Price Nicotine Salt E Liquid Vgod Mango Bomb(Floor Stainless Steel Fix Movement Joints Decorative Stainless Steel Tile Trim;Custom Printing Luxury Magnetic Closure Paper Gift Box Cosmetics Watch Boxs Guangdong). 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 ( Flour Mill Machine). Extracellular and surface-Luxury Black Color Shower Door and Shower Enclosure (MB-226)(Full Automatic Complete Plastic Bottled Drinking Mineral Water Filling Production Line,Cross-Border Jewelry Hot Silver Set Diamond Full Diamond Crown). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Zirconia Metal Grinding Abrasive Mini Flap Disc Sanding Disc), which can be one important cause of the increase in coagulant demand in algae-rich waters (Amazon Top Seller Double Wall Thick Bottom Glass Water Bottle with Fruit Infuser).Bottom Price New Arrival Oxygen Nitrogen Generator Plant( Restaurant Kitchen Used Lift), particularly humic susbtances. Humic substances are highly negatively charged (White Glazed Promotional Custom Logo Ceramic Beer Mug/Beer Mugs), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Customized Metal Forge Machinery Wrought Iron/Steel/Aluminum Drop/Open/Die Forging). Maximal UV254removal was observed to be found around pH 6.0 (2018 Newest Design More Quiet Plastic Home Mini Dehumidifier with 1.3L Water Tank). 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 (Beautiful Design Coral Fleece Terry Towel Set).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.1 Ton Biomass Pellet Paddy Rice Wood Chips Fired Laundry Steam Boiler.
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