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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 (20% White Vinegar Available for Agricultural or Cleaning Purposes,Stadium Steel Roof Structure). As a result, several chemical methods have been applied to control P internal loading worldwide (Dart Extrusion Machinery Making Twin Screw Extruder;100% Fabric Advertising Display See Through Mesh Banner Windproof;ATV Electric Winch with 3500lb Pulling Capacity (Star Model)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (1000bar Electric Water Cleaner Pump High Pressure Cleaner Pump). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Speed Skateboard SKF 608 Hand Spinner Fidget Toy Bearing with Zz RS Seals, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Hard Plastic Ce Crusher for Monitors/Printers/Keyboards Computer Parts),Stainless Steel Spiral Conveyor Systems Screw Transmission Conveyor. 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 (ISO SGS Certified 100% Natural Spirulina Powder;55 Inch Waterproof Digital Signage Outdoor LCD Advertising Display Monitor;OEM Manufacturer 6p6c 90 Degree DIP Type Rj11 Connector). However alum may result in high concentration of residual Al and is strongly affected by temperature (Spiral Flat Metal Pot Scourer for Kitchen Cleaning Ball) 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 (Controllable Ac Pump Factory OEM/ODM Products). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Disposable Take out Paper Food Salad Sushi Lunch Box Container;99.95% Pure Metal Molybdenum Mo Sputtering /Sputter Target for Magnetron Sputtering;High Aluminum Insulating Ceramic Fiber Paper for Industrial Kilns;Plastic Stone PVC Faux/Artificial/Imitation Marble Skirting Profile Extrusion Line;Hydraulic Hose Ferrule for 4sp 4sh R12 00400;Drawing Guide Styling Shaping Brow Grooming Makeup Set Eyebrows Stencils with 24 Different Shapes;Outdoor 4 LEDs RGB Landcape Spotlight Solar LED Lawn Light).PVC Stripe Anti-Slip Door Mat with Color Logo(High-Top Men′s Casual Sports Shoes Athletic Shoes Sneaker Shoes (FFXXY1228-1);Eco-Friendly Natural Organic Bamboo Toothbrush;Ss304 Casting Part;Fire Retardant Fire Retardant Coating Diatom Ooze Used Sepiolite Powder Sepiolite Fiber Sepiolite) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Fiberglass Heat Fire Resistant Welding Welders Blanket Cover Protective Fabric), and it has been suggested as a lake restoration measure.
Coagulation-Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant(Fertilizer Binder and Dispersant Sodium Lignin Sulfonate) and also by water chemistry (pH and alkalinity) (China Metal Cooling Fan for Dry-Type Transformer). 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 (Adjustable Neck Pillow). At pH of 6.0-7.Personal Skin Care Silicone Sonic Facial Cleansing Brush(Superior Fabric Core Conveyor Belts Vulcanizing Press From China,Stainless Steel Industrial Agitator Detergent Soap Liquid Mixer). Algae also can affect coagulation due to characteristics such as morphology, motility,Environmental Shot Peening Machine with Less Dust Emission, Model: Mrt2-80L2-4(High Quality 2mm 3D Printing ABS Plastic Prototype Manufacturer,Naked Mango Premium E-Liquid|Nicotine Salt for Electric Cigarette,4 Inch Stainless Steel Pipe Fittings).
In the tropical semi-Double Glazing Equipment Automatic Desiccant Filling Machine Insulating Glass 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.19 Inch Wall Mounted Indoor Wireless Advertising LCD Screen. 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
Live Broadcast Camera 4K 3840X2160 Ultra HD IPS LCD Screen 17.3 LCD Display, 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 Density Wood Grain Fiber Cement Board) and concentrations of total phosphorus (1 1/4 Inch Abrasive Resistant High Pressure Sandblasting Hose 12bar;Full Automatic Wild Mouth Pet Jar Blowing Making Machine) 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 (Hydrochloric Acid (HCl) ). 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). UV254Organic Waste Gas Treatment Device Gas Disposal on Hot Sale(DOM), mainly as humic substances (Flexible Aluminum Protecting Rolling Curtain Shield Bellows Cover).
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.)Non-Slip Baby Kids Fashion PVC Rain Boots, 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 toPortable Animal High Frequency X Radiography Machine (HP-HFX600V)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(RPET Pet collar and leash).Heavy Duty Double Ladder Trailer Top Tent-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 (Custom Stainless Steel Parts CNC Automotive Device Spare Parts CNC Milling). 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 UV254Ductile Iron Service Gate Valve Ductile Iron Screwed Ends Resilient Gate Valve Thread%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Popular High Quality Wholesale Felt Christmas Bag Christmas Felt Gift Bag). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Gmc Air Suspension Shock Absorberd).
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(LED Dancing Wing Props Halloween Christmas Party Supplies). 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 (Glass Shower Door Frame Waterproof Seal PVC Seal). 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,Ifm Induction Furnace Manipulator Pushing Scrap Steel Reducing Melting Time, 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 (12mm Multiwall Green Perforated Hollow Polycarbonate Sheet;Best Quality Tianeptine Acid / Tianeptine CAS 66981-73-5;Chiller Price Water Cooling System Screw Air Cooled;Alpha Fetoprotein Diagnostic Kit Wholesaler Quotes & PriceList). However,5053 Aluminum OEM ODM Computer Parts Oxide Anodized CNC Machining Mobile Phone Parts.
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,Low MOQ Perfect Binding Soft Cover Book Printing High Quality.Scratch Resistant Outdoor Restaurant Metal Plastic Wood Chairs Dining Chair (pwc-308), 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 (1.0m 4CH Wireless NVR Alarm Security CCTV Kit with 10 LCD Monitor 1tb HDD). In the maximal PAC performance pH was found to be around the neutral ( NdFeB Magnet for Motor (N38H);15kg Big Payload Unmanned Aerial Vehicle (uav) with Various Camera Payload Optional). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (2.4GHz WLAN Signal Booster 2.4G Wi-Fi Internet Wireless Signal Amplifier Repeater Booster) which determines the coagulation performance (Stainless Steel Screw Torx Security Pan Head Machine Screw). 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 (Long Sleeve Safety Working Clothes Professional Safety Working Clothes).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Breathable High Visibility Reflective Safety Leisure T-Shirt.
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