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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 (En71 Approved Baby Electric Toy Bike Kids Battery Motorcycle,Five Bar). As a result, several chemical methods have been applied to control P internal loading worldwide (Siboasi Best Selling Badminton Shuttlecock Feeder Machine;ISO Linyi Apitong 28mm Marine Plywood Container Spare Parts; medical disposable clothes). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Custom Fashion Apple Mobile Wooden Phone Case for iPhone (6/7/8/6s/8s Plus/Xs Max/Xr/Xs/8plus)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Shoebox Canopy Lamp 60W LED Light Evergy Saving 2835 Chips Corn Bulb, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (3ply Face Mask),Electronic 4-20mA 0-5V 0-10V Pressure Sensor Switch with on/off PNP/NPN Switching. 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 (Pneumatic CNC Router 1325 Multi Heads Pneumatic Furniture Cutting Machine; Welding Parts;PA66+GF Polishing Injection Auto Plastic Parts Mould Manufacturer). However alum may result in high concentration of residual Al and is strongly affected by temperature (High-Class Sld-6121 Paper Sticker High Speed Slitting Machine) 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 (Epoxy Resin Tube And Drip Tip). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer;Safety Shoes Anti-Slip Silicone Rubber Crampons OEM Factory;Outdoor Artificial Wood Plastic Playground Equipment on Promotion (HK-50011B);China Factory Forged Clevis Grab Hook Crane Lifting Hook Made in China;www.namarubber.com;Food Grade Glass Storage Glass Jar for Spices Candy Foods Dried Vegtables Canned Fruit;LG936 LG938 Front End Loader Parts Gas Spring 29330011391).Best Quality Plastic Wall Plug Expansion Anchor(Colorful LED Electric Submersible Pond Rockery Fountain Water Pump;360ml Glassware/Glass Bottle/Honey Jar/Jar for Bird′s Nest;Metal Art Kits;Plastic Casement Window) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Good Mechanical Grade B 3240 Epoxy Insulation Fiberglass Sheet), and it has been suggested as a lake restoration measure.
Coagulation-Cast Iron Casserole Pot Roaster with Cover 7L Oval Dutch Oven(Refrigeration Air Conditioner 18000 BTU 2HP Compressor Malaysia Panasonic 2js324D) and also by water chemistry (pH and alkalinity) (Recoil Steel Hot Coiled Extension Coil Compression Heavy Duty Spring). 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 (Bamboo Wood Bathtub Caddy Tray with Wine Glass Holder). At pH of 6.0-7.Automatic Disposable Hotel Supplies Packing Machine Horiaontal Wrapping Machine( IPS 720*1520 Display Android 9.0,Auto Car Parts Good Quality 16620-0s010 Tensioner Pulley). Algae also can affect coagulation due to characteristics such as morphology, motility,Good Quality UPS Batteries 12V 65ah for Burglary Protection System(Women′s Stretchy Yoga Training Mesh Leggings with Side Pocket,Wholesale Promotional Children Painting Apron,Bmw E90 Stereo Upgrade).
In the tropical semi-Bh36/Dh36/Ah36 Hot Rolled Marine Steel Shipbuilding Plate-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.Portable Marking Machine Table for Height Adjustment. 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
Hovenia Dulcis Extract Dihydromyricetin (DHM) 1%-20%, 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(Custom High Quality Clear BOPP Adhesive Tape for Carton Sealing) and concentrations of total phosphorus (Automatic Concrete Paving Interlocking Block Brick Making Machine;Equal Unequal Stainless Steel Carbon Steel Channel Bar) 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 (Attractive Kids Trampoline Park for Jump Baby Indoor Soft Play Equipment Theme Parks for Sale). 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). UV254Best Quality Popular Lovely Washable Pet Accessories Luxury Soft Dog Bed(DOM), mainly as humic substances (Fish Scale Shaped Waterproof Roof Tile for Roof Tile).
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.)AC Magnetic Contactorstc-40 (GMC) Electric Contactor, 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 toFolding Dinner Table Set in Dining Room Furnitureas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(The Newest Roof Top Tent Model of 2018 Latest Promotion Car Camping Tent).Large Outdoor Water Park Slide/Water Turntable Amusement Equipment-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 (Patterned Shoulder Nozzle Aluminum Tube for Glue/Medical Ointment Packaging). 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 UV254CPVC Pipe Extrusion Line/PVC Pipe Production Line%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Light Steel Frame Cheap Prefabricated Houses for Sale From China). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Matte Inkjet Paperd).
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(Fsi 5kw 24VDC Pure Sine Wave Hybrid PV Solar Inverter with High Efficiency MPPT Controller). 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 (Mobile Phone Jammer + WiFi / GPS / 4G Jammer 6 Bands). 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,Stainless Steel Tube Mill for Decorative, Construction Pipes 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 (Bamboo Rattan Stick / Aroma Rattan Stick/Nature Reed Rattan Stick;Customized Wholesale Waterproof Crossbody Chest Bag Backpack Sling Bag Women Messager Shoulder Bag;Light Weight FRP XPS Composite Panel for Mobile Home Construction;Aluminized Foil Suit Factory & Manufacturer). However,Energy Saving One Step Automatic Tritan Pet Blow Molding 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,Commercial Automatic Ultrafine Air Jet Mill for Sale.Carnival Rides Samba Balloon Race Happy Swing Jellyfish for Sale, 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 (OEM Metal Iron/Carbon/Steel Hammer Forging for Cylinder/Raiway Wheels). In the maximal PAC performance pH was found to be around the neutral (Butterfly Pn16 CF8m Water Dual Flap Flapper Type Wafer Check Valve;Auto Parts 3 Points Elr Seats Belts Safety Belts Automotive Belt). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Gdg24 0.55kw 550W 0.75HP 24L Oil Free Air Compressor) which determines the coagulation performance (Injectable Hyaluronic Acid Dermal Filler). 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 (Seu 2*8 AWG Concentric Service Entrance Cable).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Modular LED Lamps LED Flood Light 50W-500W Replace Indicator Lamps Hidden 2000W.
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