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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 (Flexible Plastic (PVC) Sheet with RoHS Standards (1mm-10mm),Amusement Ferris Wheel). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Nitrogen Fertilizer Ammonium Sulphate 21%N Steel Grade for Agriculture;OEM Chinese Factory Stainless Steel Flanged Gate Valves;Customized Stainless Steel CNC Machining Parts Watch Case). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Auto Parts 6W Flood LED Head Tail Car Work Light Lamps for Excavator). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Hot Sale 250ml Green Dorica Glass Olive Oil Bottle, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Food Drying Machine Industrial Vegetable & Fruit Dehydrator),Vertical Waste Plastics/Cloth/Cardboard Hydraulic Press Waste Paper Baler Baling 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 (Panfeng Bottled Water Beer Beverage Combo Cold Drink Snack Vending Machine;Aluminum LED Outdoor Solar Lawn Light for Garden;12mm 15mm18mm Pet PP Granules Strap Band Winder Machine Extruder Machine Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (Anti-High Corrosion and Wear Resistance Carving Zirconia Ceramic Car Rotor) 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 (m.tiger-water-filter.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Multi-Functional Toys Packaging Machine for Packaging of Children Toys;Linear Rail Guide/Linear Guide Way Bearing/Hiwin Mgn12h Linear Guide;Tubular Polyethylene Plastic Film Blowing Machine;Woodworking Melamine Lamination Face Veneer Hot Press Machine with Cylinder Upside;Furniture Paint Spray Baking Booth Wirth EPS Foam Panel;G-800A/800b/1080A Automatic Paper Product Making Machinery Paper Box Window Film Sticking Machine;800W One Wheel Electric Self Balance Motor Scooter Hoverboard with APP Controller).Kraft Paper Food Tray for Party, Camping, Carnival, BBQ(Wholesale Cosmetic Private Label Makeup Brush Set for 18PCS;PVC Price Label Holder with Whisky Bottle Custom for Coated Aluminium Sticker;Split Key Ring with Iron Chain Links Key Ring Set Business Keys Attachment;Palm Wax / Semi-Refined Paraffin Wax for Candle Wax / Raw Wax for Making Candle) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Bae502 Factory Direct Hospital Furniture Electric Medical Equipment Bed), and it has been suggested as a lake restoration measure.
Coagulation-High Speed Metal Pipe Automatic ERW Welded Pipe Machine(16 Strings Solar Power Equipment Combiner Box for 1000V DC System) and also by water chemistry (pH and alkalinity) (Long Range Passive EPC Gen2 Monza Chip UHF RFID Wet Inlay). 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 (6 Inch Diesel Dewatering Water Pump Wholesaler Quotes & PriceList). At pH of 6.0-7.Wholesale Factory Prices Ceramic Hair Curler Magic Hair Curler(Factory Directly Sell Cheap Discount Children Tc 65 Dirt Bike,Speed Reducer Gear Parts Aluminum Die Casting Parts for Auto Spare Parts China). Algae also can affect coagulation due to characteristics such as morphology, motility,5ton 10m Competitive Price High Quality New Telescopic Forklift, Telehandler(4.8X1.2m Autoclaved Aerated Concrete Production Line,Truck Exhaust Pipe Wg9731540002 for Sinotruk HOWO,Hotel Collection White Open-Toe Hotel Guest Bedroom Sipper SPA Disposable Slippers).
In the tropical semi-Made in China X42-X70 API 5L SSAW Steel Pipe for Oil and Nature Gas-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.Kitchenware BBQ Grill Mat Toaster Oven Liner for Bakeware. 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
Wholesale Brosilicate Glass Smoking with Black Triple Layer /Triple Arm Straight Glass Water Pipe, 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(High Temperature Resistant Waterproof Double Sided Industrial Adhesive Transparent Tape) and concentrations of total phosphorus (CNC Precison Red Painting Titanium Alloy Machinery Parts;Mc Cable Wholesaler Quotes & PriceList) 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 (Promotion Custom Polyester Lanyard Strap with Metal Hooks). 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). UV254Extra White Masterbatch 60% Anatase TiO2 for PE Films(DOM), mainly as humic substances (168cc Racing Go Kart for Sale Sx-G1101 (lxw) -1A with Bumpers Gc2008 for Sale).
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.)Taiwan Swiss Type CNC Wheel Lathe Ck50L CNC Slant Bed Lathe Turning Lathe Machine, 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 toThermoplastic TPE Granules Making Machine for Grass Fillingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Wholesale Free Sample 250g Flat Bottom Resealable Ziplock Coffee Bag).HVAC Duct Making Machine, Metal Duct Machine, Auto Duct Line 3 for Sale-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 (Portable Solar Lantern with Built-in Solar Panel). 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 UV254Bodybuilding Supplements Polypeptide Hormones Injectable Peptides Ipamorelin CAS: 170851-70-4%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Welding Turning Roll for Pipe Welding Hdtr-1000). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Sourcing Service Chinad).
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( Cargo Box). 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 (2020 Sale Stuffed Meatball Processing Meat Ball Making 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,Fast Speed Packing Machine Small Candy Packaging Machinery Price, 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 (Excellent Quality High Effciency Pop Can Bottle Filling Machine;HDPE Vented Nestable and Stackable Plastic Fruit Vegetable Crate for Storage;High Quality Custom Design Women′s Buttery Soft Classic Fashion Leopard Print Leggings;Battery Traffic Cone Warning LED Light for Road Safety Solution). However,Custom Printing Luxury Magnetic Closure Paper Gift Box Cosmetics Watch Boxs Guangdong.
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,Flexible DC12V/24V SMD 2835 Blue Christmas Light LED Strip.High Temperature Alternative Stainless Steel Band in Different Package, 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 (Electric Hand Circular Saw for Wood Cutting 185mm). In the maximal PAC performance pH was found to be around the neutral (Quality Assurance Refillable Nitrogen Gas Cylinder;4 Port FTTH Splice Box for Optic Fiber Termination and Sc Connection). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (48-in X 8-FT Embossed White Fiberglass Reinforced Plastic Panel) which determines the coagulation performance (Ip Ptz Camera Controller With Joystick). 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 (Customized of Fragrance Salt Bath Bombs/Bath Fizzers Bath Bubble for SPA).
Handle Adjustable Magic High Quality Microfiber Magnet Mop for Home Cleaning 1045, charge and density, factors that influence directly in flock sedimentation.Competitive Prices Gypsum Board, Gypsum Plasterboard, Drywall( Fitness Towel with PVC Pouch;Small Travel Backpack Foldable Camping Outdoor Bag). 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 (HOWO 12cbm Asphalt Spraying Truck Bitumen Sprayer Tank Truck Distributor Road Construction Machinery). Extracellular and surface-Outdoor Full Color P6mm Front Maintenance LED Display(1 Year Warranty Used CNC Milling Machine Center,Hot Sale Stainlesss Steel Forged Pipe Nipple Threaded Nipple (KT0561)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation ( Made in China Superior Black T Bolt), which can be one important cause of the increase in coagulant demand in algae-rich waters (90ml Straight Side Round Shape Glass Honey Jar with Lug Cap).Sachet Sauce Packing Machinery for Honey Stick(High Speed Liquid Brass Water Rotary Joint Union), particularly humic susbtances. Humic substances are highly negatively charged (Pp Spun Filter Cartridge), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (European Waterproof Wall Mounted Solid Wood Bathroom Cabinet Sq-201). Maximal UV254removal was observed to be found around pH 6.0 (Rigid Style Presentation Box with Lift off Lid). 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 (Fertilizer Salt Spice Nuts Beans Rice Grain Weighing Filling Packing Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.SPD Belt Conveyor Idler Frame, Roller Frame, Through Idler Frame.
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