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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 (High Quality Hf Vacuum Dryer Machine China Supplier,Phone Display Touch). As a result, several chemical methods have been applied to control P internal loading worldwide (Cooling Water Chemicals Scale Inhibitor and Corrosion Inhibitor for Power Plant;Men′s Watch High Quality Steel Quartz Wrist Watch (72057);OEM Foundry Factory Custom Aluminum Die Casting Products with CNC Machining). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Poultry Farm Chicken House Breeding Farm Machinery H Type Layer Cage). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Receipt Book/Invoice Book/Business Form Book, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Rectangle Transparet PIR Optical Fresnel Lens (8203-1)),Best Price Lifting Face Body Shaping Portable Anti Cellulite Laser 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 (Yaye 18 Hot Sell Waterproof 300W CREE LED High Bay Light /300W LED High Bay Lighting with Ce/RoHS;Ce Certificate Factory Price Food Grade Type Pressure Level Sensor;Excellent Performance EPE Foam Sheet Making Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hospital All Kind of Adult Child Old Man Disposable SpO2 Sensor) 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 (Wafer Butterfly). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Factory Price Rotary 1530 4 Axis CNC Router for Promotion;Drawstring Backpack String Bag Sports Waterproof Sackpack Gymsack Gym Bag;61539 Double Handle 4 Inch South American Style Faucet;3 Axle 50-80t Cimc Low Bed Trailer Lowboy Semi Trailer Trcuk Tractor Trailer;DIN 6921 Carbon Steel Hex Flange Nut and DIN934 Hex Nut;Us Type Drop Forged Self Colored Shoulder Eye Bolt;Four Color Printing Gloss Art Paper Hardcover Book).Comfortable and Soft Cat Pet Bed Pet Supplies Mini House for Cat(Environmental Luminescent White Light Glow in The Dark Powder Pigment;7000*4000mm Double Drilling Spindles Drilling Machine in Boiler Flange Bridge Processing;www.jumpamusement.com;XCMG Official Manufacturer Xe370ca China Hydraulic Crawler Excavator) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Electric Convection Bread Bakery Oven Made in China), and it has been suggested as a lake restoration measure.
Coagulation-Standard Vertical Rotary Automated Smart Tower Car Parking System(Biogas Digester Double Membrane Gas Holder Anaerobic Fermentation Tank) and also by water chemistry (pH and alkalinity) (Chemshun Y-Shape Pipe Liner Used in Iron and Steel Manufactueres). 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 (Beeswax Wraps). At pH of 6.0-7.Stainless Steel Water Filter Housing RO Systems(Commercial Stainless Steel Footprint Salt Water Flake Ice Maker Machine,Disposable Polypropylene Protective Head Wear Bouffant Cap). Algae also can affect coagulation due to characteristics such as morphology, motility,Vertical Automatic Computer Control Roll Slitting Rewinding Machine for BOPP(Kyn28-24 24kv Medium Voltage Metal-Clad Blokset Switchgear,Tsautop 1.52*18m/Roll Chameleon Pearl Car Wrap Trailer Wrap Cost,Metal Building Materials Iron Steel Black Bar Customized Screw).
In the tropical semi-Custom Wall Hanging Flower & Plant Plastic Garden/ Nursery Pots-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.PVC Shrink Sleeve for Glass Bottle Capsule, Shrink Wine Cap. 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
Adhesive Cut Table Heat Press PU Flex Vinyl/Film for T-Shirt, 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(38crmoala Nitrided Single Screw and Barrel for Extruder Machine) and concentrations of total phosphorus (Household Home Appliance Stainless Steel Electric Kettle Swk-40b;Good Quality Factory Directly Miniature Ball Bearing 603) 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 (FDA Approved Disposable Biodegradable Foam Packaging Boxes for Fast Food). 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). UV254Yahsi Super Narrow Bezel 55 Full Color HD LCD Video Wall with Splicing LCD Screen(DOM), mainly as humic substances (Good Price High Torque 12mm Low Speed Small Geared Motor).
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.)Textile Machine Parts Multiple Pattern Box, 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 toProfessional High End Phone Remote Control Smart Touch Switch PCB/PCBAas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(OEM Natural Massage Essential Oil Hydrating Soothing Body SPA Essential Oil).2020 Sale Stuffed Meatball Processing Meat Ball Making Machinery-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 (Industrial RO Water Purification-1500gpd with Black Cabinet (0.25T/H)). 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 UV25494% STPP Sodium Tripolyphosphate /Sodium Triphosphate Industry Detergent%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Wiiboox One Mini Wholesale Rapid Prototyping DIY Printing Machine Mini Desktop 3D Printer). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Simple Lever Air Release Valve; Air Vent for Clean Waterd).
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(600L Stainless Steel Beer Fermentation Tank 3-Vessels Brewhouse). 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 (Slim LED Lightbar Automotive LED Lights Bar for Offroad Vehicles). 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,Copper Wire Multi Cores 4/6/8 Shielded Alarm Cable Security System, 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 (3 Fold Telescopic Ball Bearing Drawer Slide Rail;L Shape Outdoor Sofa Set with Cushion and Coffee Table (DW-SF1906);Intelligent Roll Printing Machine for PP Woven Sack Printer;Colored Rolling Papers). However,Yarmax Manufacturer! Hot Sale! Top Sale Open Frame Electric Start Diesel Generator 5.8kVA Ym9500e.
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,106cm TV Background Decorative Wallpaper China Design.Top Quality Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant, 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 (Geometric Tall/Large Plants Glass Terrarium Planter Pot Box for Christmas Decorative). In the maximal PAC performance pH was found to be around the neutral (530ml Glass Drinking Water Bottle with Silicone Sleeve&Handle Lid;Cotton Garden Work Glove with Single Side PVC Dots). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Filter Press Small-Size Metal Plate Hydraulic Press Machine) which determines the coagulation performance (Hot Cup Holder). 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 (Double Rows PCD Segments 7 Inch PCD Cup Wheel for Concrete).
Pneumatic Vertical Threaded 3-Way Ball Valve, charge and density, factors that influence directly in flock sedimentation.Poultry Farm Pellet Feed Press Machine Equipment with Durable Ce Quality(EU Standard Top Quality Portable Indoor Playground Equipment;Best Brush Customized Synthetic Flat Foundation Makeup Brush Professional Cosmetics Accessory). 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 (Black Cohosh Extract Triterpene (Cimicifuga racemosa extract)). Extracellular and surface-Pedstal Electric Stand Fan 5 Speed Control Air Cooler(A1 Cutting Board,Chubont Hot Selling Waterproof Duffel Trolley Bag Size 19/22 Inch). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Household Multi-Function 16.8V Double Speed Lithium Cordless Electric Drill), which can be one important cause of the increase in coagulant demand in algae-rich waters (Fast Food Catering Airstream Trailers or Mobile Electric Airstream Food Truck Food Caravan Cart).Perforated Decorative Aluminum Metal Curtain Wall Single Panel Sheet for Curtain Wall Decoration(China Desktop Zirconia Dental Porcelain Sintering Furnace 1700c Four-Sided Heating), particularly humic susbtances. Humic substances are highly negatively charged (www.plus1motors.com), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Logo Branded Hi-Spec Heavy Duty Tool Box Set with Parts Organiser Tray). Maximal UV254removal was observed to be found around pH 6.0 (VOD 1550nm Direct Modulated Optical Transmitter RF Input Local Program). 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 (Transparent Toiletry Bag Zip Pouch Plastic Makeup Bag).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Custom Ductile Iron Casting Parts Gray Iron Sand Casting.
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