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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 (1 2 3 4 5 6 8 10 12 14 16 18 20 24 26 Inch Pneumatic Flanged Valve with Actuator,castironmaria.com). As a result, several chemical methods have been applied to control P internal loading worldwide (Car Parts Thermostat Housing with 4-Pin Sensor for Renault;Factory Wholesale Pillow Low Price Polyester Microfiber Down Alternative Cushion;Strong and Durable Outdoor Wedding Furniture Resin Solid Wood Wimbledon Folding Chair). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (ASTM A500 Grade a Mild Steel Material Shs Hollow Sections). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Construction Props Scaffolding Shoring Push Pull Adjustable Prop Tyt Scaffolding, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Android Pos Terminal),Aluminium Coating Cheap Lunch Cooler Bag with Durable Hard Liner. 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 (OEM Design 24 & 30 Cavities Cold Runner Spoon Mould;100% Cotton Heavy Duty Workwear Wholesale Work Clothes;High Speed Aluminum Alloy + ABS Shell Video Type-C to HDMI Cable). However alum may result in high concentration of residual Al and is strongly affected by temperature (Used Jam/Tomato/Chilli Pasty Manual Filling Machine with Sauce Material) 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 (Face Mask Disposable). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (24PCS Sunflower Waterproof Super Bright Battery LED Road Warning Lamp;Portable Silicone Food Fresh-Keeping Kitchen Storage Freezer Bag;Drainage Rubber Grasss Ground Stabilisation and Play Area Anti Slip Rubber Mat;Linyi Jianzhong Square Veneer Tube Dryer Wood Veneer Dryer Machine for Plywood;Diamond Mesh Garden Fence;High Precision CNC Milling Aluminum Case Electronic Spare Parts Custom Watch Housing;IP65 Waterproof Metal Distribution Box and Power Metal Box).7 Liters Vertical Type Commercial Butchery Manual Sausage Filler(Anti-Slip Bath Slipper Folding Travel Slippers Slippers Disposable;Masturbators Adult Sex Toys Japanese Love Doll;Double Layer Co-Extrusion Rotary Die-Head Film Extruding Machine;Top Quality Poultry and Livestock Automatic Manure/Organic Fertilizer Composting System) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Chinese High Quality Plastic Spice Jars for Vinegar and Sugar Jam Organizer), and it has been suggested as a lake restoration measure.
Coagulation-E-Bay Hot Sales Silicone Baby Dolls for Kids Toys(Reinforced Stainless Steel 306L Wire Wrap Johnson Type Strainer Screen) and also by water chemistry (pH and alkalinity) (172X150X38mm Axial Ventilation Cooling Fan for Electric Cabinet (TXA38S-172)). 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 (Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant). At pH of 6.0-7.AAC Block Making Machine Line Supplier/AAC Block Machinery(4 Drawer Steel Office Vertical Filing Cabinet,Colorful Electric Bike Folded E Bike Foldable Scooter Motorcycle Folding Frame All Ai Alloy). Algae also can affect coagulation due to characteristics such as morphology, motility,Desktop Fiber Laser Marking Machine with Computer Price $3300(CO2 Gas Shielded Stainless Steel Welding Wire (ER308L),Recyclable Bottle Bamboo Material 5ml Perfume Oil Packaging with Amber Glass Inner,AISI 201 304 316 409 Cold Drawn Bright Hot Rolled Stainless Steel Round Bar Square Flat).
In the tropical semi-Eco Recycled Kraft Paper Box for Salad and Lunch-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.Heavy Duty Galvanized Stacking Steel Pallet Shelving with Posts. 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
Guangzhou High Quality Spare Parts 2 Years Warranty Fit for BMW and Mercedes Benz, 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(Metal Solar Powered Crab Shape Outdoor Garden Ornaments LED Solar Lighting) and concentrations of total phosphorus (Electronic Home Refrigerator Freezer AC 110-230V Mini 12V Car Fridge;Tapioca Flour Thickener) 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 ( Motor Cable Wire Electrical Power Cable). 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). UV254Custom Design Stainless Steel Sheet Metal Fabrication Box Cover(DOM), mainly as humic substances (Class 1 Foam Rubber Insulation Pipe for Air Conditioner).
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.)Digital Printing Pillow for Sofa with Metallic Printing, 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 to Campingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Double Wall Polycarbonate).Micron Circular Stainless Steel Filter Disc-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 (Floor Stainless Steel Fix Movement Joints Decorative Stainless Steel Tile Trim). 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 UV254Wholesale Portable Travel Bamboo Tooth Brush Holder%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Custom Printing Luxury Magnetic Closure Paper Gift Box Cosmetics Watch Boxs Guangdong). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs ((S)-2-(1-Aminoethyl)-4-Fluorophenol Hydrochlorided).
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(Cross-Border Jewelry Hot Silver Set Diamond Full Diamond Crown). 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 (Zirconia Metal Grinding Abrasive Mini Flap Disc Sanding Disc). 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 Quality Folding Us Plug 5V 1A USB Travel Charger, 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 (Customized Metal Forge Machinery Wrought Iron/Steel/Aluminum Drop/Open/Die Forging;2018 Newest Design More Quiet Plastic Home Mini Dehumidifier with 1.3L Water Tank;Beautiful Design Coral Fleece Terry Towel Set;Bread Mixing Machine Factory OEM/ODM Products). However,Tubular Polyethylene Plastic Film Blowing 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,LED Screen Facial Comedo Nose Blackhead Cleanser Zit Extractor Tool.Custom Dye Sublimation Printed Phone Lanyard ID Badge Holder with Logo Custom, 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 (Lx85-9m Wheeled Digger Digging Height 6536mm 8 Ton Mini Wheel Wood Grabber). In the maximal PAC performance pH was found to be around the neutral (Clear Lens of CHP CO2 Laser Protection Goggles for CO2 Laser Beauty Equipment with Frame36;Genuine 1m USB Date Charging Cable for iPhone). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Filter Fiber Car Engine Cabin Air Filter for Mazda) which determines the coagulation performance (Mini High Temperature Clothing Labels Screen Printing Machine Factory). 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 ( Customized Available).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Pond Electric Copper Wire Clean Water Pump with European Plug.
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