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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 Quality Free Sample Woven Label for Garment Accessories,Sand Casting for Ductile Iron). As a result, several chemical methods have been applied to control P internal loading worldwide (Rls9 Zz-2RS Ls11 Lj-1-1/8 Cixi Inchi Wheel Roller Ball Bearing;Shenzhen Customized Metal Stamping Parts Fabrication Service;Narrow Hub Connection Brake Discs for Sprockets (TLK603 RLK603 55X110)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Self-Propelled Ride on Concrete Floor Grinder Grinding Machine Gyg-780, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Acid Etched/Printed/Patterned/Art/Mirror Glass for Decoration Glass),The Best Venlo Type and Multi-Span Glass Greenhouse for Agriculture. 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 (Micron Circular Stainless Steel Filter Disc;PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble;China New Technology Swimming Pool Heat Pump (MDY50D)). However alum may result in high concentration of residual Al and is strongly affected by temperature (Agriculture Machinery Belt Banded Cogged V-Belt) 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 (Organic Compost Fertilizer Fermentation Plant). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Nonwoven PP Fabric Nonwoven Needle Punched Geotextile;12-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape;Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case;Anti-Aging Dredger UHMWPE/HDPE Sand Mud Oil Dredge Floater Pipe Pipeline;3/8 Inch DOT Approved Brake Hose with SAE J1402;600g Synthetic Fiber Ceiling Filter/Roof Filter/ Roll Filter for Spray Painting Booth;High Quality Galvanized Pan Head Self Drilling Screw).PC Black Plastic Material Polycarbonate PC Granules Resin(High Efficiency Cleanroom Mini Pleat HEPA&ULPA Air Filter Media Pack;4.0cbm Automatic Feeding Mixer Concrete Batch Truck with Rotation Drum;Machining Brass Parts;Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Factory Supply Urban Outdoor Street Mobile Sweeper Road Sweep Truck with Brushes), and it has been suggested as a lake restoration measure.
Coagulation-Duplex Hydraulic Oil Filter for Lubrication System(Spraying Rubber Asphalt Emulsion Waterproof Coating/Liquid Rubber Coating) and also by water chemistry (pH and alkalinity) (Best Price Split Air Conditioner Stand/AC Stand). 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 (3.3kva Diesel Generator). At pH of 6.0-7.Automatic Chicken Farm Poultry Battery Cage System for Layer(Hotel Wall Mounted Infrared Battery Electric Liquid Automatic Soap Dispenser,Jumbo Drilling Rig with Three Arms (HFG-33J)). Algae also can affect coagulation due to characteristics such as morphology, motility,27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike(1.0 Ton Small Backhoe Crawler Mini Excavator Digger Machine for Sale,2017 Cheap China Pistol Safe Security Gun Safe Lock,Nitrile Rubber Foam Sponge Tube Foam Pipe Insulation).
In the tropical semi-Beautiful Design Coral Fleece Terry Towel Set-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.China Products/Suppliers. Prefabricated Metal Shed Steel Structure. 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
Surge Protector Lightning Arrester Lightning Arrester, 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(En71 Approved Baby Electric Toy Bike Kids Battery Motorcycle) and concentrations of total phosphorus (Siboasi Best Selling Badminton Shuttlecock Feeder Machine;China Roughing End Mill Cutter) 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 (Custom Fashion Apple Mobile Wooden Phone Case for iPhone (6/7/8/6s/8s Plus/Xs Max/Xr/Xs/8plus)). 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). UV254Decorative Round Shape Colorful Empty Aroma Reed Diffuser Custom Glass Bottle with Wooden Cap(DOM), mainly as humic substances (Pneumatic CNC Router 1325 Multi Heads Pneumatic Furniture Cutting Machine).
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.)Fuller Gearbox Parts for The Shacman Man Fast Gearbox Transmission, 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 toUltrasonic Welding Machine for Cutting Sponge Scouring Pad Scoureras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Original 0 Degree LCD Panel Polarizing Film for The Monitor).OEM Customized Cast and Forged Stainless Steel Chains and Shackles with Hot DIP (HDG) Galvanized-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 (China Factory Forged Clevis Grab Hook Crane Lifting Hook Made in China). 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 UV254Al2O3 Alumina Ceramic Porous Foam Filter Plate for Non-Ferrous Alloy & Aluminum Alloy Casting%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Food Grade Glass Storage Glass Jar for Spices Candy Foods Dried Vegtables Canned Fruit). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Sport Compression Protective Elastic Arm Elbow Sleevesd).
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(Colorful LED Electric Submersible Pond Rockery Fountain Water Pump). 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 (360ml Glassware/Glass Bottle/Honey Jar/Jar for Bird′s Nest). 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,China Magic Panel Matrix 36X15W Single LED Controllable LED Beam Moving Head Light, 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 (Refrigeration Air Conditioner 18000 BTU 2HP Compressor Malaysia Panasonic 2js324D;Recoil Steel Hot Coiled Extension Coil Compression Heavy Duty Spring; IPS 720*1520 Display Android 9.0;Wholesale Fashion Accessories Male Mens Jewelry Manufacture). However,Wholesale Gym Equipment Adjustable Boxing Target.
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,A2 Fireproof Inorganic Mineral Material for A2 ACP Panel ACP Sheet.70cm Foldable Folding Lap Desk Bamboo Laptop Bed Table Stand Tray Desk Adjustablebt-2204, 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 (Auto Car Parts Good Quality 16620-0s010 Tensioner Pulley). In the maximal PAC performance pH was found to be around the neutral (Women′s Stretchy Yoga Training Mesh Leggings with Side Pocket;Wholesale Promotional Children Painting Apron). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Poultry Farming Automatic Chicken Feeding Pan System) which determines the coagulation performance (16x2 Lcd Module Monochrome). 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 (600W Mini Lathe Metalworking 7 X 14 Tool Turning Machine).
Jaws End Us Type Drop Forged Turnbuckle Rigging, charge and density, factors that influence directly in flock sedimentation.Hanna Good Quality Door Spray Paint Machine(Custom High Quality Clear BOPP Adhesive Tape for Carton Sealing;Automatic Concrete Paving Interlocking Block Brick Making 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 (OEM Custom Cotton Twill Flat Top Military Army Hat and Cap). Extracellular and surface-Multi Color Dual Slides Crayon Inflatable Bouncer Castle(Refractory Glass Wool Thermal Insulation Fibre Glass Wool,Wood Grain Vinyl Films/Self Adhesive Decorative Paper for Furniture). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Attractive Kids Trampoline Park for Jump Baby Indoor Soft Play Equipment Theme Parks for Sale), which can be one important cause of the increase in coagulant demand in algae-rich waters (Fish Scale Shaped Waterproof Roof Tile for Roof Tile).Poultry Farming Equipment Chicken Cage for close farming house Automatic design(Hydraulic Control Valve-100A Angular Stable Water Level Valve), particularly humic susbtances. Humic substances are highly negatively charged (Drawstring Wedding Candy Organza Promotional Bag Custom Party Bag Christmas Wine Bag), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Direct Thermal Label with Premium Quality Adhesive Sticker Label). Maximal UV254removal was observed to be found around pH 6.0 (Wholesale Room Ozone Generator for Fruits and Vegetables). 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 (Folding Dinner Table Set in Dining Room Furniture).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Cbb65 Air Conditioner Capacitor Polypropylene Film Capacitor.
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