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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 (Round Pipe Welded Pipe Middle Size for Chemical Companies,Medical Nebulizer Mask/ Oxygen Mask/Nasal Oxygen Mask). As a result, several chemical methods have been applied to control P internal loading worldwide (Quality Medium Stapler with Staples Remover;G02f12L Tempered Glass Shower Cabin;Cold Rolled Steel Coil Galvalume/ Hot Dipped Galvanized Steel). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Tandem Axle Semi-Trailer Lift Germany Mechanical Overslung Suspension). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Juice Filling and Canning Machine/Juice Maker Machine/Juice Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (m.anebon.com),Flexible Arm India Tapping Machine for Industrial Production. 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 ( 7050;115cm Mini Sex Doll for Man Big Breast Love Doll;Fancy Design Formal Dress Shirt Short Sleeve for Women). However alum may result in high concentration of residual Al and is strongly affected by temperature (Pear or Regular Shaped Screw Lock Metal Quick Link) 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 (Aluminum Facade Panel/Aluminum Plastic Composite Panel Interior Wall Decorative). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Traffic Safety Plastic Signs/Accessible Fire Exit Emergency Signs;Popular Lifejacket EPE Foam Life Vest for Water Safety Equipment;14G Auto Computerized Collar Flat Knitting Machine;Portable Metal and Nonmetal CNC Fiber Laser Marking Machine;Shopping Handbag;Long Span Galvanized Light Weight Steel Structure;China Gingseng Extract Ginsenosides 15% 20% 80%).OEM Trailer Parts Drop Axle Forging Spindle(PVC Shoe Upper with LED Light for Kids Slide-on Slippers;Plastic PVC Car Mat Making Line / PVC Coil Carpet Car Seat Cutting Machine;Needle punched nonwoven fabrics;Duct Outdoor Single-Mode Gyfy Fiber Optic Cable) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Handrail Fitting / Stainless Steel Round & Square Tube Connector), and it has been suggested as a lake restoration measure.
Coagulation-Fashion Italian Style Hotel Furniture Wooden Marble Dressing Table(Kitchen Stainless Steel Washing /Wash Double Bowl White Sink) and also by water chemistry (pH and alkalinity) (Factory Price 50W LED Corn Bulb E26/E39/E27/E40 Base Indoor and Outdoor Industial Lighting). 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 (2 Micron Fuel Filter). At pH of 6.0-7.Automatic Continues Iron Wire Straight Line Wire Drawing Machine(FRP Insulated PU Foam Composite Panel for Refrigerated Truck Body,Whole-Sale 25cm Cleanroom M3 Wipes Cleaning Tissue Cellulose Wipers). Algae also can affect coagulation due to characteristics such as morphology, motility,Black Bracelet Leather USB Drive Free Design Logo(1325/1530/2030/2040 CNC Woodworking Router Machine with Cheapest Price and Big Discount Is on Big Sale,Wholesale Portable Travel Bamboo Tooth Brush Holder,China Manufacturer 1kg 5kg Fully Automatic Rice Sugar Packing Machine).
In the tropical semi-Waterproof Magnesium Oxide False PVC Ceiling Panel-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.Refrigerant R134A with Refillable Tped Approved Cylinder. 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
PVC Cross Joint Pipe Fittings Equal Pipe Cross, 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(V9 37kw 220V 380V Various Motor Type Control Flexible and Adaptable AC Drive) and concentrations of total phosphorus (Automatic Non-Woven T-Shirt Bag Making Machine with High Efficient;Pictures Printing A5 Document Pouches with Slide Zipper) 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 (Personal Skin Care Silicone Sonic Facial Cleansing Brush). 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). UV254Electrical Insulation Flexible Crepe Paper Tube for Transformer(DOM), mainly as humic substances (UV Coating Surface Treatment and Indoor Usage Plastic PVC/WPC/Spc Flooring Extruder Machine).
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.)Custom Souriau Connector Header with Cable, 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 toMotorcycle Parts Motorcycle Brake Caliper and Brake Master Cylinder for Wave110as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cnc Manchining Welding Parts).Height Adjustable Removable Foldable Feeding Baby High Chair-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 (Supply12HP Copeland Scroll Air Conditioner Compressor Zr144kce-Tfd-522 for Sale). 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 UV254High/Middle/Low Back Office Chair / Executive Computer Chair / Ergonomic Mesh Office Chair%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (15.6 Slim 30pin Edp Screen LCD Display N156BGA-Eb2 N156bge-Eb2 for Laptop Screen Replacement). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Precision Small Transmission Spur Browning Internal Gear for Gear Boxd).
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(12mm LED RGB String Light/ LED Pixel with SD Card 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 (Coupling Capacitor for No Partial Discharge Signal Detection). 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,Rust Resistance Anti Climb Protective Aluminum Durable Outdoor Metal Fence for Garden/Factory, 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 Precision Machinery Plastic Parts with Injection Mold; Type Dlo 2kv Msha;7 Custom Voice Blank Recordable Video Invitation Greeting Card;Cryogenic Piston Pump). However,Carbon Steel Zinc Countersunk/ Flat Head Self Tapping Screw.
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,Factory Supply Concrete Pump Spare Parts S Valve for Putzmeister, Cifa, Schwing, Sany Pump Truck.Shockwave Therapy Machine Shock Wave Physiotherapy Equipment Air Pressure Shockwave Sw10, 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 (Easywell & Minston Electric Platform Scale with Height Meter BS-200lp). In the maximal PAC performance pH was found to be around the neutral (Auto Styling Car Interior Accessories Central Armrest Storage Glove Trau Box for Ranger;Burglar Alarm PIR Microwave Motion Sensor Srdt15). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Made in China Colored Heat Resist Strength Silicone Rubber O-Rings for Excavator) which determines the coagulation performance (Fruit Infusion Water Bottle with Handle Lid). 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 (Professional Manufacturer Large IR Touch Screen Monitor 32 43 55 65 Inch for Commercial Kiosk).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.PP Surface Self Adheisve Roof Underlayment.
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