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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 (Dn630mm Plastic Pipe Butt Fusion Welding Machine,Little Boy Fleece Jacket with Hood Ear Winter Reversible Jacket). As a result, several chemical methods have been applied to control P internal loading worldwide (Manufacturer Vertical Turbine Fire Pump 1HP Inline Fire Pumps;Wet and Dry Vacuum Cleaner SL18125p 1gallon /4litres 1.5HP Portable Poly Stanley;12 PCS CRV 1/2 Dr. Socket Set for Car Repair Tools). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Invt Bd 3000W/5000W Hybrid Solar Power Inverter for Solar Power System Home). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Digital Electronic Body Fat Personal Bluetooth Health Weighing Scale (SBF097BT-WTP), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Rfid Retail Market),6061 6063 Extrude Aluminum Extrusion Profile Section Supplier. 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 (Adjustable for Home Appliance Bimetal Temperature Regulator Kst Thermostat;Custom OEM Sheet Metal Stainless Steel Aluminium Sheet CNC Laser Cutting Service;Han Star 3015 1000W/1500W Fiber Laser Cutting Machine Laser Cutter for Carbon Steel Pipe/Tube Low Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (3-Axle 30mt LPG Haulage Truck Trailer Depot Gas Transportation Tanker) 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 (High Power Drill). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Heavy Duty Cast Ductile Iron Manhole Cover with Concrete Infill;Agriculture Cultivator Springs Double Spring Tines 3.5-12mm;Wholesale Price DC12V 2835 S-Shape/Zigzag LED Flexible Strip;Wholesale High Quality USB Charging Data Cable for Original Apple iPhone 7 Charger Cable;Engineered Vinyl Flooring;Printed Circuit Board Mobile Charger PCB Board LED PCB Board Module;Long Service Life Smooth Lead Screw Tr3.5X0.61).Excellent Quality Wooden Cosmetic Display Counter for Retail Store(Computerized CNC Turning Machine Metal Lathe Price Ck63L;8mm PVC Coated Galvanized Steel Wire Rope for Lifting;Custom Purple Square Spray Perfume Glassware Cosmetic Glass Bottle;Manufacture RP HP UHP Graphite Electrode 300mm 350 with Nipples for Smlting) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Good Quality UPS Batteries 12V 65ah for Burglary Protection System), and it has been suggested as a lake restoration measure.
Coagulation-Small Silent Biogas Electric Generator for Biogas Plant(Stainless Steel/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration) and also by water chemistry (pH and alkalinity) (Stainless Steel Tube Electric Heater Industrial Immersion Cartridge Heater). 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 (High Demand Products Quick Dissoving Empty Capsule). At pH of 6.0-7.Basket Filter Made of Standard Basket and Slanted Basket(Wholesale Events 6FT Wood Dining Round Table, Wall Fan 3 in 1-Competitive Price). Algae also can affect coagulation due to characteristics such as morphology, motility,Beautiful Lvt Eco-Indoor Wood Grain Click Planks Vinyl WPC Flooring(CNC Router 2030 3D CNC Foam Rubber Gaskets Oscillating Knife Leather Cutting Machine,High Quality Tungsten Carbide Gripper Inserts for Chuck Jaws,Drainage Cover).
In the tropical semi-Yellow Corrugated PE-Al-PE Gas Pipe with Size 16mm to 32mm-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.Android Handheld Barcode Scanner Industrial PDA. 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
1220X2440mm fashion Design Melamine Flakeboard/Particle Board, 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((Made in China gold sellers) SPA Swimming Pool Water Filter Pump) and concentrations of total phosphorus (Interior Fireproof Rock Wool Wall Insulation Mineral Thermal Insulation Board;Lospeedlaser Auto PVC / ABS / PMMA / PC / Ak / PU / Ep CO2 Laser Marking System with Glass Tube) 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 (Gondola Supermarket Shelf Candy Shelf for Confectionery Equipment). 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). UV254Direct Steering Gear DC Motor with Low-Speed High Torque Spare Parts(DOM), mainly as humic substances (Men Solar Analog-Digital Quartz Movement Sport Wrist Plastic Watch).
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.)1630 Auto Feeding CO2 Laser Cutting Machine for Textile, Fabric, Cloth, Leather, 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 toCustomized Non-Standard Machinery Part CNC Aluminium Machining CNC Metal Milling Serviceas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cosmetic Ingredient).Export Quality Straight Dried Instant Flavor Kelp Seaweed Noodle-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 (20A 12/24V Auto Intelligent LCD Solar Panel Charge Controller (QWP-SR-HP2420A)). 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 UV254Custom Aluminum Die Casting Parts for Medical Equipment%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Hot Sale Outdoor Car Carport Shelter with Low Price). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Quality SMT Nozzle Cleaner for Pick and Place Machine Nozzle Cleaningd).
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(Hygiene Grade Stainless Steel U Clamped Tee Pipe Fittings Elbow). 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 (Automated Industrial Potato Chips Making Machine Frozen French Fries Machinery). 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,High Quality Asphalt Waterproof Emulsion Bitumen Emulsion Coating, 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 (New Addition and Cheap Frame Upward 4 Column Hydraulic Press;Br42 Red Color Mushroom Head Push Button Switches;High Density Storage Rack Heavy Duty Drive in Pallet Racking System Design;Hitachi Engine). However,Wc67y Hydraulic CNC Aluminium Plate Rolling Press Brake/Bending Machine.
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 200W IP66 China LED Flood Light.Cbhs-F32 Hydraulic Oil Transfer Gear Pump for Fuel Forklift, 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 (Factory Price Courtyard Waterproof LED Outdoor Lighting Solar Street Light). In the maximal PAC performance pH was found to be around the neutral (Automatic Abrasive DIY Sandblaster for Motorcycle Outer Assy Surface Processing;Multilayer 6-Layer Green Mask Immersion. Gold PCB). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Wholesale Price AA06400 SMT FUJI Nxt H08 H12 Series Nozzle) which determines the coagulation performance (Material Child Bicycle). 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 (Stainless Steel Plate Frame Customized Sheet Metal Processing Laser Cutting).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Multi Span Venlo Type Agriculture Production Glass Greenhouse.
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