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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 (Stainless Steel Sheet 254smo,Black Monopod). As a result, several chemical methods have been applied to control P internal loading worldwide (40X50cm Log 60kg 100kg 200kg Portable Courier Platform Scale;China LED Magnetic Alumnium Under Cabinet LED Door Light Bulb for Shelf Lighting 12V/24V;Brass Screen Mesh Brass Wire Mesh Brass Mesh Cloth). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Modern Design Stainless Steel Handrail Post Glass Balustrade Handrail). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Fully Automatic Kid Ride on Toy Car / Rechargeable Baby Car, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Electric Operating Table Surgical),ISO Factory of Disc Cutter for Tunnel Boring Machine. 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 (Organic Fertilizer Production Line for Manure Treatment;Tz03D High Quality China 20-40HP Garden Tractor Front End Loader Hot Sale in New Zealand;Android Data Cable Mobile Phone USB Cable Mobile Phone Cables). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Chrome Cast Iron Mud Sand Slurry Pump Parts) 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 (Red Primary School Uniforms Kids School Uniform Design). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal ( VDE;Pet Strap Production Line with Good Quality;XCMG Official 150 Ton Rough Terrain Crane Rt150;Factory Direct Sale Baseball Uniform for Adults;Bamboo Coffee Mugs;Red Color Garage Matting Rubber Sheet Flooring Manufacture in China;Laser Cutting Machine 500W 1000W 2000W Fiber Laser Pipe and Tube Cutting Machine).Color Shifting Chameleon Pigment for Car Paint Factory(Fiberglass FRP GRP Composite Glassfibre Stick Bar;Sw Type BOPP Packaging Adhesive Tape Coating Machine;Large Portable Bluetooth Speakers;3mm/0.3mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (OEM Hyaluronic Acid Facial Cream Cosmetic for All Skin), and it has been suggested as a lake restoration measure.
Coagulation-Harem Sweat Sport Casual Women Pants for Jogger(Wholesale MIG Stainless Steel Welding Wire Soldering Wire Super Quality Welding Wire) and also by water chemistry (pH and alkalinity) (PLC Controlled Transfer Cart Rail Drive Steel Platform). 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 (Stand Up Pouch Packing Machine). At pH of 6.0-7.Toroidal Ferrtie Core Common Mode Choke for DC-DC Converter(Carbon Steel Lifting Chain Eye Slip Hook with Latch ,Manufacturer Black Painting Seamless Carbon Steel Tube Hose Pipe). Algae also can affect coagulation due to characteristics such as morphology, motility,High Quality Firefighting Rescue Equipment Safety Rescue Tripod( Tail,Pdf Manual Brick Making Machine Design Lego Brick Making Machine Second Hand Brick Making Machine,Pure Cotton Cover UK Standard Size White Polyester Pillow).
In the tropical semi-Wholesale Price DC12V 2835 S-Shape/Zigzag LED Flexible Strip-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.57-5 Micron Micro Powder Mill Pulverizer Grinding Plant. 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
Chinese Furniture Outdoor Garden Furniture Aluminum Sofa Sets, 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(7.5HP Centrifugal Circulation Swimming Pool Water Pump) and concentrations of total phosphorus (90L 4 Drawers Dry and Safety Case Desiccator Cabinet for Equipment Storage;Wires Electrical) 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 (High Quality Low Price Square Pipe CNC Plasma Cutting Tool). 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 Aluminum/Aluminium Extruded Housing by Using CNC Machining(DOM), mainly as humic substances (USB Powered UV LED Photocatalyst Electric Bug Zapper Mosquito Killer).
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.)1300*700*700mm Vertical CNC Milling Machine CNC Lathe CNC Machine Center CNC Machine Tool, 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 toSilicone PU Ms Acrylic Sealant Adhesive Automatic Cartridge Filling Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Plastic Recycle Machine).Factory Stocked 500ml Double Wall Plastic Glitter Water Bottle Diamond Lid Insert Layer-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 (Custom Electronic Wire Harness with Jst Molex Housing Connector). 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 Best Quality Goof Price Tpo Flat Roofing Waterproof Membrane%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Handsfree Car Kit Wireless Multipoint Speakerphone with Visor Clip). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Metal Ridge Cap Machined).
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(Best Price 1325 Woodworking CNC Router Machine Equipment). 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 (100mm Thickness China Roof/Wall EPS Sandwich Panel From China Suppliers). 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,Custom Flexible FDA Silicone Rubber O Ring, 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 (HDPE 1mm 2mm Plastic Strips /Tapes Manufacture for Decorate Christmas;Touch Screen Display Module Control Panel for Instrument;Environmental Shot Peening Machine with Less Dust Emission;Freshwater Pearl Butterfly Flower Bride Hairpin). However,Good Quality Delicious Instant Fresh Pasta Noodle.
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,High Quality Non-Standard Metal Components Precision Machining Mold Parts.60W 6040 Engraving Machine Laser for Paper Cutter Machine, 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 (Roll up High Quality Luxury Comfort Spring Mattress). In the maximal PAC performance pH was found to be around the neutral (High Quality and Precision Chroming Zinc Plating CNC Machined Hardware for Medical Instrument;A4 A5 Discoloration PU Leather Planner Agenda Diary Notebooks with Stamping Logo). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (PS126 Electric Automatic Surface Vortex Peripheral Motor Water Pump) which determines the coagulation performance (XCMG off-Road 65ton Heavy-Duty Tipper Tnm311). 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 (Agricultural Utility Model Rod-Spray Machine Hung Onto Roller Tractor).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Metal Slatwall with Wooden Platform on Base, Wall Rack.
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