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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 (Good Quality Cheap Bluetooth Music Zero Gravity Shiatsu Massage Chair,Decoration Flooring). As a result, several chemical methods have been applied to control P internal loading worldwide (Metallzied Polyester Film 9um MPET Film for Capacitor Use;Custom Mono 0.96 Inch Mini Monochrome 128X64 Small OLED Display;Wholesale Gym Equipment Adjustable Boxing Target). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Good Quality Wholesale Men′s Leather Sneakers Boots). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Throttle Body Valve Plastic Heater Inlet Pipe 55559352 for GM Chevrolet Cruze, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (ESD Antistatic Carbon Fiber Figer Palm Coated Glove),Ce Certificate Factory Price Food Grade Type Pressure Level Sensor. 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 (12ml Small Dropper PE Plastic Medicine Bottle;PVC Edge Banding Printing Machine Tape Banding Machine Wire Banding Machine;Middle Duty 20 Discs Harrow for 50 HP Tractor). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hot and Cold Temperature Thermal Shock Testing Equipment) 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 (Wg9000360152/3 Foot Brake Valve for HOWO Steyr Truck). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Students Bags School Backpack Childrens′ Shoulder Bag Yf-Sbz2215;Newest Hot Sales Metal 360 Degree Reading Glasses with Case;Hydraulic Press Machine Deep Drawing Press 100 Ton;Screw Type Hot Feed Cold Feed Rubber Extruder Rubber Machine Extruder;etc.;FC/Upc-St/Upc Single Mode Simplex Fibre Optical Patch Cable;Wholesale Men′s Leather Waterproof Outdoor Trekking Boots).Quick Drying Waterproof Silicone Sealant Construction Adhesive Glue for Glass(Ss 316L 5 Round 30 Inch Stainless Steel Cartridge Water Filter Housing for Industrial Oil Filter;Bicycle Parts Steel Bike Repair Stand Display Rack (HDS-004);Ce Approved Farm Equipment 22HP ATV Flail Mower for Sale;PVC Insulation 1.27mm Pitch UL2651 24AWG 6p-64p Flat Ribbon Cable) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Quality 100% Cotton Pullover Warm Wholesale Men Custom Printing Embroidery Hoodies), and it has been suggested as a lake restoration measure.
Coagulation-Customized Promotional 100% Cotton 6 Panels Baseball Cap with Printing Logo(Carrier Roller for Sany Hydraulic Excavator Sy16-Sy850h-8) and also by water chemistry (pH and alkalinity) (Forging SAE4140 S31803 Steel Crusher Eccentric Shaft). 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 (18 Gauge Black Wire). At pH of 6.0-7.Biodegradable Packaging Small Plastic Compartment Storage Box for Food(Car Repair Equipment Underground Garage Lift with Double Scissor Lifts,Building Material Colorful Stone Coated Metal Spanish Roofing Tile). Algae also can affect coagulation due to characteristics such as morphology, motility,Hot Sale MID-Temperature Commercial Dehydrator Large Capacity for Nuts, Fruit&Vegetable, Meat Drying(Auto Price Crankshaft Position Sensor 90919-05043,Duplex Hydraulic Oil Filter for Lubrication System,Diy Solar Fountain Pump).
In the tropical semi-Empty Toner Lotion Pump Glass Bottle Cosmetic Bottles-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.THK Linear Guide Shs Hsr SSR 15 20 25 30 35 45mm for CNC. 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
Long Service Life Smooth Lead Screw Tr3.5X0.61, 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(4 Fibers Wall-Mounted FTTH Distribution Box) and concentrations of total phosphorus (80kw Electric Canopy Diesel Generator Powered by Cummins with Ce/ISO;Landscape Light) 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 (Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift). 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). UV254Custmoized High- Quality Decoration Mirror Stainless Steel Curtain Wall(DOM), mainly as humic substances (1/2 Inch Brass Stem Handwheel Gate Globe Valve).
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.)Fiber Laser Marking Machine with Jpt Mopa 120W Laser Source for Cutting Thin Metal, 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 toGlass Mike Bottle 200ml 250ml with Screw Cap Strawsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Sliding Shelf Brackets).Must 4kw 2HP Pump Power Inverter Ags Bts Available-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 (Cee/IEC 32A 5p 400V 3 Phase European Standard Plug). 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 UV254Food Cardboard Paper Packing Box for Pastry%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Semi-Automatic Hydraulic Leather Football Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Stainless Steel Animal Feed Pellet Bone Mud Grinder Mill 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(Modern Style Prefabricated Steel Structure Poultry House). 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 ( Splicing Machine S6). 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,1390 Mixed CO2 Laser Cutting Machine for Wood Acrylic MDF Stainless Steel Carbon Steel Plywood Cut, 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 (Customization Industrial Steam Boiler Repair Parts Steam Economizer Boiler Pipes;Floor Mounted Glass U Clamp Channel for Glass Balustrade;High Quality Curve Spear Tunnel Bolt for Concrete Ring;Injection Mold). However,Water Heater Single Head Shrinking 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,Discount HOWO High Pressure LPG Delivery Dispenser Truck.Ldd-100 High Efficient Electric DTH Drilling 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 (Brand New Forklift with Double Front pneumatic Tire). In the maximal PAC performance pH was found to be around the neutral (Automatic Small Round Bottle Water Washing Filling Capping Machine;MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (3 Inch Diamond Resin Bond Polishing Pads for Concrete Floor) which determines the coagulation performance (Diamond Blade Wet Saw Tile Cutter). 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 (Hairise 2120 Series Transfering Flat Belt Type Modular Belt for Conveyor System /Mechanical/Foods).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Hot Sale 3 Players Mini Amusement Carousel Horses Rides Carousel Merry Go Round Kiddie Ride.
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