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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 (Gear Operated Cast Iron Wafer Type Butterfly Valve,Micro USB Female B-Type Receptacles Verticle DIP). As a result, several chemical methods have been applied to control P internal loading worldwide (Street Lighting 50W 100W 150W 200W LED Street Lamp Source Outdoor LED Street Light;Jfe-9243 9 Motors Stainless Steel Glass Straight Line Grinding Machine;Custom Clear Acrylic Chinese Tea Table (BTR-Q1012)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Stainless Steel Electric Heating Mixing Kettle for Food Industry). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Automatic Multi Function Side Drilling Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Colorful Heat Wrap Cap Seal Sleeve Metal Roll Foil Label PVC Shrink Wine Tin Capsule for Bottles),Resealable Ziplock Round Bottom Biodegradable Food Packaging Pouch Wholesale in China. 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 (High Efficiency Nylon Fiber Separator in Waste Tire Recycling Line;High Quality C5/C3 Grinding Ball Screw From Taiwan;High Speed Wheel Hub Bearing/Automotive Wheel Bearing Units/Wheel Bearing). However alum may result in high concentration of residual Al and is strongly affected by temperature (Manufacturer of Various Color Graduation Tassel Honor Cords) 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 (Picnic Bag For 2). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (CNC Router Machine Heavy Duty Steel Frame 2030 CNC Router;Makute Electric Power Planer Woodworking Wood Cutting 82mm 600W;China Label Screen Printing Machine Suppliers; Water;20mm Metal Laser Cutting Machine;Ring Die Sawdust Wood Pellet Making Machine Line;Honkon Beauty SPA Skin Tighter and Acne Removal Mesogun Injector Beauty Machine).Yaye 18 Hot Sell Waterproof 300W CREE LED High Bay Light /300W LED High Bay Lighting with Ce/RoHS(Prime SPCC Electrolytic Tin Plate for Making Cans;Large Size 300mm Low Noise 55dB IP44 Air Blower for Public Places;650W DMX Cold Firework Flame Fountain Cold Spark Machine Fireworks Effect;Microfiber Wiping Lens Cleaning Cloth for Glasses) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Double Layer Waterproof and Durable Asphalt Shingle Roof Tile Roofing Shingles), and it has been suggested as a lake restoration measure.
Coagulation-Wholesale Fashion Designer Customs Sunglasses Square Men Sunglasses(2018 Amusement Park Children Outdoor Playground Equipment for School (HS806001)) and also by water chemistry (pH and alkalinity) (Small Industrial Sewage Treatment Unit for Industrial Wastewater Treatment). 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 (Stiletto Pumps Shoe). At pH of 6.0-7.Rechargeable Battery Powered Indoor WiFi Camera with Custom APP(Low Cost Commercia Plastic Polycarbonate Used Agricultural Greenhouse for Sale, Disc-Chain Automatic Feeding System). Algae also can affect coagulation due to characteristics such as morphology, motility,Luxury Design 70GSM 110GSM 3D Bedding Bed Sheet(20% White Vinegar Available for Agricultural or Cleaning Purposes,Dart Extrusion Machinery Making Twin Screw Extruder,Non Woven Gift Tote Bag).
In the tropical semi-Good Quality CNC Contour Sponge Foam Profile Vertical Cutting Machine-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.Professional Palm Handheld Veterinary Ultrasound Diagnostic System. 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
Custom Logo Small Beer Mug One Ounce Mini Stein Glass, 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(1000bar Electric Water Cleaner Pump High Pressure Cleaner Pump) and concentrations of total phosphorus (ISO SGS Certified 100% Natural Spirulina Powder;Cmc For Chewing Gum Bases) 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 (Spiral Flat Metal Pot Scourer for Kitchen Cleaning Ball). 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). UV254PVC Coated Galvanized 12 Guage Iron Baling Wire(DOM), mainly as humic substances (Disposable Take out Paper Food Salad Sushi Lunch Box Container).
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.)Kh CNC Plasma Cutting Machine 1530 CNC Controller, 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 toDrawing Guide Styling Shaping Brow Grooming Makeup Set Eyebrows Stencils with 24 Different Shapesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Chain Motor Hoist).High Quality Anti-UV Artificial Garden Grass Carpet-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 (Eco-Friendly Natural Organic Bamboo Toothbrush). 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 UV254Sw Type BOPP Packaging Adhesive Tape Coating Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Fire Retardant Fire Retardant Coating Diatom Ooze Used Sepiolite Powder Sepiolite Fiber Sepiolite). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Lamella Slant Clarifier Used to Environmental Protection Equipmentd).
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(Fertilizer Binder and Dispersant Sodium Lignin Sulfonate). 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 (China Metal Cooling Fan for Dry-Type Transformer). 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,19mm Fancy Plywood for Door Use and Whole House Decorative, 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 (High Quality 2mm 3D Printing ABS Plastic Prototype Manufacturer;Naked Mango Premium E-Liquid|Nicotine Salt for Electric Cigarette;Tempered/Toughened Glass/Window/Shower Door Float Glass (T-TP);www.sinoriseind.com). However,Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder.
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 M3.5-M6.3 Fine Thread Black Drywall Screw for Gypsum Tornillos.Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift, 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 (Hsc8 6-4A Mini-Type Self-Adjustable Crimping Plier). In the maximal PAC performance pH was found to be around the neutral (High Density Wood Grain Fiber Cement Board;1 1/4 Inch Abrasive Resistant High Pressure Sandblasting Hose 12bar). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Dumpling Wrapper Machine Dough Pressing Machine Dough Sheet Cutter to Do Tortilla Flat Bread) which determines the coagulation performance (128X64 0.96 OLED Display SSD1306 Yellow and Blue Color). 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 (Cow Horse Trailer Ramp Stall Stable Rubber Mat).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Mini Cargo Elevator, Restaurant Kitchen Used Lift.
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