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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 (12L Ice Chest Ice Bucket Plastic Cooler Box,medical glass vials). As a result, several chemical methods have been applied to control P internal loading worldwide (Hovenia Dulcis Extract Dihydromyricetin (DHM) 1%-20%;Wedding Concert Festival Party Activity Remote Control LED Glow Wristband LED Flashing;High Speed Spiral Dough Mixers 50kg Flour for Bread). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Natural Stone Moulding Lines Baseboard Skirting Moulding for Border Line/ Wall or Floor Skirting). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,UL Approved Rubber Covered Hose/BS6391 Type 3 Rubber Covered Hose/1.5/2.5, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Factory Supply Protective Film for Household Articles Furniture Surface Protective Film),10m 3.5mm Male to Female Audio Cable for iPhone iPod. 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 (Full Automatic Sachet Cartoning Pack Machine (ZH100);Plastic Slat / Plastic Leakage Dung Floor for Chicken House / Poultry Farm;Waterborne Epoxy Resin for Waterborne Epoxy Coatings). However alum may result in high concentration of residual Al and is strongly affected by temperature (Theater Hall VIP Writing Tablet and Desk Commercial Seat Press Cinema Chair) 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 (Cool Playground Parent-Child Amusement Park Battery Powered Car Ride). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Greatly Improved Brown Coal Briquette Machine With Low Energy Consumption;RoHS Stainless Steel Passivated Ground Pin 14.6X1.5mm;Outer Side Mirror Left and Right Rearview Mirror for Skoda;Monofilament Fibrillated Twist Wave Polypropylene Fiber PP Fiber for Concrete;Roughing End Mill;NdFeB Magnetic Strong Sintered N45 Rare Earth Permanent Neodymium Magnets for Motor;Constant Temperature Hot Water Machine Swimming Pool Heat Pump).Js500 Twin-Shaft Concrete Mixer for Block Machine(Decorative Marble Pattern Coated Aluminum Sheet/Coil for Building Material;Shoebox Canopy Lamp 60W LED Light Evergy Saving 2835 Chips Corn Bulb;m.hgfencing.com;LDPE Plastic Garbage Bags for Construction Wastes) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (15 Years Factory OEM Plastic Injection Molding Kid Learning Machine Parts), and it has been suggested as a lake restoration measure.
Coagulation-40W Hot Sale Acrylic Ceiling LED Panel Light(Fast Building Luxury Mobile Modular Container House Material Living Container Buildings) and also by water chemistry (pH and alkalinity) (Ifm Induction Furnace Manipulator Pushing Scrap Steel Reducing Melting Time). 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 (Ball Screw For Electric Pruner). At pH of 6.0-7.Industrial Use Sandwich Panel Container for Offices/Construction Sites(Fenbendazole CAS43210-67-9 Pesticide Vetetinaries Good Manufacturing Practice,Adhesive Cut Table Heat Press PU Flex Vinyl/Film for T-Shirt). Algae also can affect coagulation due to characteristics such as morphology, motility,OEM Foundry Factory Custom Aluminum Die Casting Products with CNC Machining(New Model Polished Porcelain Glazed Marble Ceramic Floor Tiles for Project,Wholesale Sport Wear Mens Gym Running Polyester T Shirt,Custom Blinds).
In the tropical semi-Custom Foldable Storage Basket with Metal Handle and Lid-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.Automatic Dry and Wet Pig Feeder for Pig Feeding Equipment. 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
Vci PE Film for Ferrous Metal with Anti-Rust Performance, 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(Custom PVC Shrink Capsules for Liquid Bottle) and concentrations of total phosphorus (Newest Double Color WPC 3D Wood Grain Plastic Composite Flooring;Electrical Qquipment Stainless Steel Pipe (SUS 304L)) 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 (Fashion Double Striped Non-Slip Entrance Mat). 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). UV254Solar Garden Peacock Stake with Solar Light for outdoor Decoration(DOM), mainly as humic substances (Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow).
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.)Carrier Roller for Sany Hydraulic Excavator Sy16-Sy850h-8, 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 toWholesale Comfortable Men′s Winter Leather Snow Bootsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Mini Water Valve Plastic).4.3 IPS Display 1080P Dash Cam 12 Mega Pixel Rear View Mirror with Parking Monitor, G-Sensor-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 (High Quality Free Sample Woven Label for Garment Accessories). 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 Top Supplier 2- (4-Chlorophenoxy) -2-Methylpropionic Acid with Best Price CAS: 882-09-7 C10h11clo3%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Rls9 Zz-2RS Ls11 Lj-1-1/8 Cixi Inchi Wheel Roller Ball Bearing). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Magnetic Steel Rodd).
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(Narrow Hub Connection Brake Discs for Sprockets (TLK603 RLK603 55X110)). 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 (Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155)). 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,Transparent Single Crystal Alumina Sapphire Jewel Bearing and Components, 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 (China New Technology Swimming Pool Heat Pump (MDY50D);Agriculture Machinery Belt Banded Cogged V-Belt;Nonwoven PP Fabric Nonwoven Needle Punched Geotextile;China Manufater of Ss 304 316 Stainless Steel Pipe Inox Tube Stock). However,Handle Operation Flanged Lined PFA Butterfly Valve (D41F46).
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,Plastic Filter/Plastic Mbbr Filter Media for Water Treatment/ Electric Kettle Filtration.High Quality Portable Deep Well Solar Pump Solar Water System, 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 (12-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape). In the maximal PAC performance pH was found to be around the neutral (Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case;Anti-Aging Dredger UHMWPE/HDPE Sand Mud Oil Dredge Floater Pipe Pipeline). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (600g Synthetic Fiber Ceiling Filter/Roof Filter/ Roll Filter for Spray Painting Booth) which determines the coagulation performance (Natural Wood Color Easily Installed WPC waterproof Outdoor Flooring (HK-XM1801)). 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 (High Quality Galvanized Pan Head Self Drilling Screw).
New Design Comfortable PU Cemented Men and Boy Sandal, charge and density, factors that influence directly in flock sedimentation.Quality Assured Large Freight Volume Fire Resistant Rubber Conveyor Belt(High Efficiency Cleanroom Mini Pleat HEPA&ULPA Air Filter Media Pack;4.0cbm Automatic Feeding Mixer Concrete Batch Truck with Rotation Drum). 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 (Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw). Extracellular and surface-6 Panel Embroidered Fashion Fitted Cap Custom(www.cauntamachinery.com,Factory Supply Urban Outdoor Street Mobile Sweeper Road Sweep Truck with Brushes). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Spraying Rubber Asphalt Emulsion Waterproof Coating/Liquid Rubber Coating), which can be one important cause of the increase in coagulant demand in algae-rich waters (Best Price Split Air Conditioner Stand/AC Stand).3/2 Way 3h210 Airtac Hand Control Manual Pneumatic Air Valves(Hotel Wall Mounted Infrared Battery Electric Liquid Automatic Soap Dispenser), particularly humic susbtances. Humic substances are highly negatively charged (Aluminum Foil Laminated with Pet Film Compounded with LDPE), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Jumbo Drilling Rig with Three Arms (HFG-33J)). Maximal UV254removal was observed to be found around pH 6.0 (1.0 Ton Small Backhoe Crawler Mini Excavator Digger Machine for Sale). 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 (2017 Cheap China Pistol Safe Security Gun Safe Lock).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Metalized Pink Color 3ml 5ml 10ml Perfume Roll on Container Bottle with Gold Aluminum Cap.
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