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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 (Hot Sale Copolymer Coated Aluminum Foil Tape for Cable,Hnx Flameproof Metal Brass Simple Armored Explosion Proof Cable Gland). As a result, several chemical methods have been applied to control P internal loading worldwide (Stainless Steel 1000W Pipe and Sheet Fiber Optic Laser Cutting Machine;R134A Best Price Copeland Compressor Zp385kce-Twd-522;Carbide Nozzles Yg6X Tungsten Carbide Sandblasting Nozzles Boron Carbide). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Quality Adjustable Ball Valve Lockout for 13-70mm Pipe Bd-F05). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,European Waterproof Wall Mounted Solid Wood Bathroom Cabinet Sq-201, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Safe Stainless Steel Cylinder Fitting Center Door Lock Sliding Glass Door Lock),GMP Certified Collagen Softgel for Fish Collagen. 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 (Preparation Concrete Vibrator Shaft with Japanese Coupling;500ml Stainless Steel Insulated Double Wall Vacuum Drinking Bottle (SL-550);Textile Waterproof Motorcycle Trousers for Sale). However alum may result in high concentration of residual Al and is strongly affected by temperature (Non-Mainstream Leather Retro Bracelet/ All-Match Fashionable Leather Bracelet) 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 (Apple Chips Making Machinery Manufacturers Cheap Price). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal ( 316 Slot Stainless Steel Tube with Glass;Ce 20 Aluminum Frame City Electric Folding Bike with Lithium Battery;Latest Simple Personalized Designs Circular Rotating Blanks Metal Custom Key Chains;Handles Operated Cast Iron EPDM Seat Wafer Butterfly Valve;End Mill Cnc Milling;FM200 Automatic Fire Suppression System for Electrical Room;Wholesale Resealable Self Standing Washing Detergent Power Liquid Spout Package Bag/Pouches).Digital 8 Channel Tinnitus-Masking Programmable Powerful BTE Hearing Aid(China Rotary Kiln for Sponge Iron with Competitive Price with 0.9-42tph;Automatic Monochrome Crystal Shoe Injection Molding Machine;General Electric 3 Wire 30AMP Dryer Cord;Portable Adjustable Basketball Hoop for Teenager) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Professional 808nm Diode Laser Hair Beauty Equipment Hair Removal), and it has been suggested as a lake restoration measure.
Coagulation-China Modern Office Furniture Wooden Display Shelf (CAS-FC1829)(Ferrite Magnet Used in Motor as Magnetic Strip) and also by water chemistry (pH and alkalinity) (Three Lines Production Three Side Seal Pouch Making Machine). 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 (CATV Fttc Outdoor Optical Node with Eoc and ONU). At pH of 6.0-7.Plant Stands & Accessories Glass Hanging Flower Pot Bracket(Cement Roofing Sheets Pigment Yellow Iron Oxide Prices,Oversized Canvas Travel Tote Luggage Weekend Duffel Bag). Algae also can affect coagulation due to characteristics such as morphology, motility,All in One Salad Maker, Slicer, Strainer, Cutting Bowl, Blender, Server, Salad Cutter Bowl(Air Cooler Skin Cooler Zimmer Cryo Skin Cooling Device,Multi-Functional Heat Reflux Ethanol Extraction and Concentration Equipment 200L for Herb,Effective Cardboard Paper Automatic Die Cutting Machine).
In the tropical semi-Yellow Wall Stacked Stone, Tiger Skin Yellow Cement Based Wall Stone Veneer-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.Stray Inductance 210~2100uh Frame Core Current-Compensated Common Mode Choke Coils. 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
Metal Solar Powered Crab Shape Outdoor Garden Ornaments LED Solar Lighting, 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(PCBA Indutrial Control Assmebly Quick Turn PCB Assembly) and concentrations of total phosphorus (Garden Metal Natural Rusty Flower Decoration Product;Pdo Thread Lift Korea) 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 (China Magic Panel Matrix 36X15W Single LED Controllable LED Beam Moving Head Light). 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). UV254Electric Vibrating Massage Cream Jar for Cosmetic Packaging(DOM), mainly as humic substances (2 Storey Worker Living Block Container House Supplier).
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.)Electric Rail Transport Wagon Warehouse Transfer Vehicle, 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 toHex Phillips Torx Slotted Bits Ratchet Hand Screwdriver Setsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(00.781.7096 Flat Module Zrm2 Circuit Board).Nki Radial Needle Roller Bearing Nki 35/30 Needle Bearing with Inner Ring-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 (Glow in The Dark Pigment Luminescent Luminous Powder). 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 UV254on-Line Aoi Machine for Inspection Post Reflowing or Placement (A2000)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Custom Personalized Logos Cheap Neck Printed Custom Polyester Lanyards Ribbons with ID Card Holder). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Bio Pesticides Abamectind).
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(Korea Glittery Heat Transfer Film /Vinyl for Clothes/T-Shirt Printing Cdg-16 Light Multi). 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 (Popular Selling Sausage Casing Making Machine). 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,UL Approved Rubber Covered Hose/BS6391 Type 3 Rubber Covered Hose/1.5/2.5, 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 (Good Sale Lfc Sand Preparation and Casting Molding Line;Vegetable Herb Garden Hand Tools with Storage Box;Height Adjustable Removable Foldable Feeding Baby High Chair;Crushed Recycle Red Colored Chips Glass for Tile Decoration). However,10m 3.5mm Male to Female Audio Cable for iPhone iPod.
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,Js500 Twin-Shaft Concrete Mixer for Block Machine.40W Hot Sale Acrylic Ceiling LED Panel Light, 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 (ISO Humidity Control Damp Proof Auto Grd Dry Cabinet 50L). In the maximal PAC performance pH was found to be around the neutral (Wholesale Factory Prices Ceramic Hair Curler Magic Hair Curler;Decorative Metal Aluminum Steel Room Divider Modular Partition for Hotel Restaurant). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (New Designer PU Fashion Ladies Backpacks Handbags for Brand Holder and Wholesale) which determines the coagulation performance (Cotton/Nylon Teflon Camouflage). 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 (Built-in Camera Shoot Photo Video Recording Multi Function Night Vision Telescope).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Vci PE Film for Ferrous Metal with Anti-Rust Performance.
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