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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 (Depilation Aesthetic Opt Shr IPL Elight RF Hair Removal Machine,Professional Custom Shiny Silver 3D Letters Metal Brand Logo Plate). As a result, several chemical methods have been applied to control P internal loading worldwide (E40/E39/E27/E26 Meanwell Power Supply 150W LED Retrofit Kits;Farrowing Crate Galvanized Swine Farrowing Crates;Dezhou China PLD Commercial Fitness Equipment Rearl Delt/Pec Fly Machine Gym Equipment). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Cheap Soccer Game Table Foldable Football Table with L Shape Leg). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Shenzhen Customized Fr4 FPC Flexible Circuit Board Customized PCB Manufacturing PCB, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Babble Express Bag),Professional Manufacturer NPT Thread Dustproof Nylon Cable Gland / Plastic Cable Gland. 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 (Competitive Price Corrugated Tubing with Braid Layer;Air Ventilator Fan Exhaust Fiberglass Cooling Fan Manufacturer;Puffed Food Automatic Vertical Packing Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature ( Customized Fancy Printing Adhesive Paper Label Sticker) 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 (Professional Manufacturer of AC Motor Frequency Inverter 4kw 380/400V). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (TXWF-110-2L 5V -24V DC Brushless Axial Stand Cooling Alarm Fan Motor;A76 Nordic Living Room Dining Room Furniture;Custom-Made Wild Bluebell Cologne Spray Perfume in Crystal Glass Bottle 30ml for Body;Aluminum/Aluminium Sliding Doors Philippines Price and Design System;High-Quality Spherical Roller Bearings 22205-230/750;90ml Cool Designer Perfume Glass Bottle with Surlyn Cap;Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle).Home Decorative Universal Electric Fireplace with Remote Control and LED Flame(Fr-218 BOPP Packing Tape Slitting Rewinding Machine;Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock;Home Textile Ins Style Active Printing Ab Pattern 4 PC Cotton Comforter Set;Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal), and it has been suggested as a lake restoration measure.
Coagulation-2018 Amusement Park Children Outdoor Playground Equipment for School (HS806001)(Soybean Quick Freezing Production Line/Vegetable IQF Freezing Production Line) and also by water chemistry (pH and alkalinity) (Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel). 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 (Low Sulfur Graphitized Petroleum Coke). At pH of 6.0-7.4 Inch Cast Iron Wafer Pneumatic Butterfly Valve(Free-Maintenance Motor Design White Light PTZ Security Cameras,Plastic Cover Aluminum A60 7W E27 LED Global Bulb). Algae also can affect coagulation due to characteristics such as morphology, motility,Wns Gas Oil Fired Boiler Hot Water Heating System(Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery,UPVC Rigid Water Supply Drain Pipe Production Line,Ghrp/Cjc 1295/Melanotan2/Fragment/Mgf/Ipamorelin Dried Powder Peptides).
In the tropical semi-China Suppliers Factory Paper Machine Industrial Ss Cylinder Mould-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.SS304 SS316 St2.9 St4.8 DIN7981 Stainless Steel Cross Recessed Pan Head Self Tapping Screws. 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
Commode, Foldable, Wheelchair, Detachable Parts (YJ-016B), 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(OEM High Quality Stainless Steel Ladies Anolog Wrist Watch Jewelry Diamond Watch 71092) and concentrations of total phosphorus (Fabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003);Car Chamois Cloth) 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 (27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike). 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 Your Design Logo Women T Shirt Fashion Cotton Casual Girl Tshirt Basic Ladies T-Shirt(DOM), mainly as humic substances (3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline).
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.)Drawing Guide Styling Shaping Brow Grooming Makeup Set Eyebrows Stencils with 24 Different Shapes, 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 toCustom Flexible FDA Silicone Rubber O Ringas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Suzhou Leading Exporter of Checking Fixture Jig for Electric Vehicle Es6 Sheet Metal).25nm Ys-2.5b1 for Unreeling Hollow Shaft Magnetic Powder Brake-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 ( Strainer). 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 UV254Lacquered PVC High Intensity and Good Elastibity Tarpaulin%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Speed China Oric Of6045 UV Flatbed Printing Machine with Dx5 Print Head). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (OEM/ODM Luxury Glass Perfume Bottle of Experienced Designerd).
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(Custom Printed Luxury Black Paper Gift Carry Shopping Packaging Bag). 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 (Newest 2′′ IPS Display Mini Dash Cam FHD1080p with 2.5D Glass Lens). 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,Detergent Camellia Seed Extract Tea Saponin 60%-98%, 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 (Stainless Steel Metal Spiral Conveyor Belt Mesh Band for Oven;Custom Product Rapid Prototype Making/Vacuum Casting/CNC Machining Rapid Prototype;Automatic Mango Juicer Filling Machine / Canned Juice Production Line;Non-Slip Lightweight Soft Bottom Toddler Kindergarten Baby Sock Shoes). However,Milk Homogenizer Pump Honey Pump Juice Emulsifying Pump.
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,Custom Own Shoes Bag Garment Brand Logo PVC Rubber Label/PVC Patch/Accessories for Cloth.Oscillating Knife Cutter for Car Seat Covers, 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 (Low-Cost Tree Stump Crushing Machine with Widely Using). In the maximal PAC performance pH was found to be around the neutral (Plant Stands & Accessories Glass Hanging Flower Pot Bracket;Seamless Circular/Square/Rectangular Steel Tube). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Foldable Full Suspension 250W Mini Pocket 20 Inch Wheel Electric Bike / Jb-Tdn05z) which determines the coagulation performance (PVC ASA Resin Colored Glazed Roof Tile Plastic Sheet Extrusion Machine Line). 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 (Lightweight New Design Girl Fashion Bags Children School Backpack).
Digital Electronic Body Fat Personal Bluetooth Health Weighing Scale (SBF097BT-WTP), charge and density, factors that influence directly in flock sedimentation.6061 6063 Extrude Aluminum Extrusion Profile Section Supplier(Humidifier Aroma Diffuser USB Portable Car Humidifier Air Humidifier;New 2 Ton Gasoline/LPG Dual Fuel Forklift Truck Price). 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 (Round 10W LED CCT Tuneable Dimmable Down Lights). Extracellular and surface-Excellent Quality Wooden Cosmetic Display Counter for Retail Store(Wholesale White Resin Wimbledon Child Folding Chairs for Wedding,Customize Cartoon Printing Logo Brand Silicone Swim Cap). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation ( Citycoco), which can be one important cause of the increase in coagulant demand in algae-rich waters (Type F High-Rise Clip Drive/Worm Hose Clamp).Small Silent Biogas Electric Generator for Biogas Plant(28L Wholesale Retail Plastic Basket Chinese Suppliers Supermarket Shopping Large Basket), particularly humic susbtances. Humic substances are highly negatively charged (Modem Wifi 4g Portable), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (New Version Breakage-Proof Multihead Weigher for Biscuits). Maximal UV254removal was observed to be found around pH 6.0 (S14-M 30~1600kVA (10KV) Oil Immmersed Distribution Transformer). 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 (FDA Approved Custom Eye Mask Packaging Bag / Mylar Foil Facial Mask Pouch / Cosmetic Cream Sachet).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Basket Filter Made of Standard Basket and Slanted Basket.
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