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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 (PC Black Plastic Material Polycarbonate PC Granules Resin,3/4′′ Female Elbow Hydraulic Flange Clamps Compression Threaded Connection). As a result, several chemical methods have been applied to control P internal loading worldwide (3mm/0.4mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration;3m 1500 Electrical Pipe Wrap Tape Vinyl PVC Coated Wire Insulation Tape;11oz Heat Transfer Sublimation Hot Water Change Color Magic Mug (Matte)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Galvanised Iron Roofing Plate/Hot Dipped Galvanized Corrugated Roofing Sheet). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Food Grade PVC Water Suction Hose / PVC Corrugated Suction Hose, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Surgical Orthopedics),Karl Mayer Machine Warp Knitting Spare Parts Karl Mayer Machine Pulley Belt. 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 (Plastic Valve with The Membrane Heat Welding Machine;Front Lifting Used Tipper Second Hand Dumper Volvo Dump Truck Original From Sweden;6 in 1 H2 O2 Hydra Facial Water Oxygen Dermabrasion Aqua Peel Skin Clean Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (CCTV Security System Projects IP Camera Factory Hikvision IP Camera) 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 (Classroom Student Response System Wholesaler Quotes & PriceList). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Factory Bulk Self-Indicating Blue Silica Gel with High Adsorption;High Quality Double Link Ra DVI D 24+1 Pin Connector;Electrical Insulation Flexible Crepe Paper Tube for Transformer;High Quality Humidity Control Chamber Artificial Climate Chamber;Fashion Women Accessories Rhinestone Bridal Heart Jewelry Set;Best Quality Hydroponic Film Greenhouse Steel Structure Construction;Stainless Steel Wire Rope Zoo Mesh Aviary Mesh for Animal Enclosure).Textile Screen Printing Mesh Polyester Material(Potable Expansion Vessel Suitable for Sanitary Water Applications;IP65 Waterproof Exterior Hanging Batten Linear Lighting LED Tri-Proof Light;Printing Dense Steel Grating;Transformer-Base Factory Equipment UPS 3 Three Phase in 3 Phase Output 60-400 kVA Online UPS) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Forged Custom Exterior French Door Wrought Iron Double Entry Doors), and it has been suggested as a lake restoration measure.
Coagulation-Hot Selling HOWO Heavy Truck 371HP Dump Truck, Tipper, Dumper Truck(92 16: 9 Motorized Projection Screens with Black Casing) and also by water chemistry (pH and alkalinity) (China Supplier Customized Pressing Stamping Parts). 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 (Gear Box Housing). At pH of 6.0-7.High-Class Sld-6121 Paper Sticker High Speed Slitting Machine( 4 Butanediol Bdo CAS 110-63-4 with Lowest Price,Marine Studless Link Anchor Chain for Sales). Algae also can affect coagulation due to characteristics such as morphology, motility,Factory Price Smart Handheld Printer V5 Hand Jet Printer Handheld Code Printer for Carton(Woma Acrylic Shower Panel Cubicle Room for Old People (Y698),15t/H Hot Selling Professional Factory Price Palm Nut Crusher Machine with Ce,Blue-Green).
In the tropical semi-Farm, Garden Irrigation Gasoline Water Pump Wp20, Wp30, Wp40-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.Commercial Industrial Fast Food Chicken Electric Gas Pressure Deep Fryer for Mijiagao. 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
220V Square Synchronous Grill Rotisserie Motor for Gas Cooker, 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(Cemented Carbide Round Rods) and concentrations of total phosphorus (Shenzhen Customized Fr4 FPC Flexible Circuit Board Customized PCB Manufacturing PCB;Goochie A8 Digital Eyebrow Embroidery Permanent Makeup Machine) 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 ( ISO9001). 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). UV2545r 200W LED Moving Head Beam 3 in 1 Stage Lighting(DOM), mainly as humic substances (Hot Dipped Galvanized 358 High Security Fence/ Anti Climb Fence).
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.)Picnic Lunch Bag Waterproof Tote Lunch Bag for Kids Adult, 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 toBig Width Different Thickness Pet Release Filmas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Customized Logo Luxury Hot Stamping Paper Wine Bag).Steel Structure Welding Steel Structure Metal Building-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 (Automatic Hamburger Patty Forming Machine/Meat Patty Press Equipment /Molding Machine). 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 UV254Chc-B07 Health Stainless Steel Germanium Bracelet for Female, Oppbag%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Natural Light Green/Beige/Pink Slate Thin Cut Surface Culture Stone). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Co2 Laser Chillerd).
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(Trunking System Busbar Bus Duct 2000A Bus Way). 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 (Automatic Defrost Supermarket Arc Sliding Island Freezer Horizontal Island Freezer). 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,92 16: 9 Motorized Projection Screens with Black Casing, 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 (UL Approved Rubber Covered Hose/BS6391 Type 3 Rubber Covered Hose/1.5/2.5;380V/220V VFD Variable Frequency Drive 50Hz/60Hz for Fun;500W/1000W/15000W CNC Laser Cutting Machine Laser Cutter for Steel Plate;New Small Wheel Loader Backhoe Wz30-10 Price for Sale). However,Alloy 6063 T5 Temper Aluminium Extrusion Customized Round Tube/Flat Tubes.
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,Colorful LCD Display High Quality Cheap Price Optical Fiber Fusion Splicer, Splicing Machine S6.15m 17m 3 Arms R Shape Trailer Mobile Spider Concrete Placing Boom on Sale, 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 (Galvanized Jaw and Jaw Type Closed Body Rigging Screw Turnbuckle). In the maximal PAC performance pH was found to be around the neutral (Cryotherapy Fat Removal Coolsculpting System Body Contouring Machine;High Precision Self-Aligning Roller Bearing 1219). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Glass Charger Plate Decoration Plates Shining Gold Rim Clear Charger Plates) which determines the coagulation performance (Android 7inch Industrial Panel Computer Capacitance Screen). 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 (Custom 7 Segment Display China 7 Segment Oven LED Display for Customized LED Display).
Geekvape Aegis Squonk Tc Kit 100W Wholesale Price E Cigarette, charge and density, factors that influence directly in flock sedimentation.Skin Cool Cold Hot Hammer Electroporation Machine for Facial Lifting (VS-885)(Building Material Steel Coil Zinc Coated Prepainted Galvanized Steel Coil;34*25cm Office File Pocket Felt A4 Document Bag). 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 (4 Inch Cast Iron Wafer Pneumatic Butterfly Valve). Extracellular and surface-5 Colors Sticker Label Flexographic Printer(Lcd Display 2.8 Inch,Wall-Mounted Wooden Commercial Bathroom Cabinet PVC Vanity with Mirror). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Electrical Insulator Fibreglass Separator for Lead Acid Battery), which can be one important cause of the increase in coagulant demand in algae-rich waters (Xinjing Wide-Mouth Kitchen Glass Square Jar for Spice).Duct Outdoor Single-Mode Gyfy Fiber Optic Cable(Environmentally Diesel Powder Coating Bake Curing Oven), particularly humic susbtances. Humic substances are highly negatively charged (70cm Rangehood), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Wholesale Custom Colorful Fabric Embriodery Patches in Garment Label). Maximal UV254removal was observed to be found around pH 6.0 (Indoor or Outdoor Power Distribution Equipment Metal Box). 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 (100% Water Soluble AAA45-P-HCl Animal Source Amino Acid Fertilizer).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Aluminium Spigot Lighting Truss, Stage Truss, Roof Truss for Sale.
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