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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 (Dto0032 Foldable Outdoor Indoor Nylon Mesh Hammock,Shockwave Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Beautiful Christmas Printed Gift Polyester Grosgrain Ribbon Satin Ribbon;Custom Stand up Composite Material Zipper Packaging Bag Candy Bag;New Model Solar Room Lighting System Lighting Kit Light in Remote Area). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Lacquered PVC High Intensity and Good Elastibity Tarpaulin). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Custom Sequin Patch for Clothing Handbag Backpack, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (acctek-cnc),Weight Loss Equipment with Cryolipolsis Fat Freezing 40K Cavitation Rflipo Laser. 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 (Factory Wholesale T5 T6 7075 6061 6063 Alloy Aluminium/Aluminum Sheet Plate; Asphalt Mixing Plant;with Pneumatic Actuator + Limit Switch Box Ball Valve (Q641F)). However alum may result in high concentration of residual Al and is strongly affected by temperature (Food Cardboard Paper Packing Box for Pastry) 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 (Red Plastic Bowls). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Flat Pharmacy Cylinder Shape Pet Plastic Pill Containers Capsule Bottles for Sale with Metal Cap;Induction Heater Electric High Temperature Furnace for Casting;Tsudakoma Zax-N Air Jet Looms Year 2007 210 Cm 2861 Dobby Weaving Textile Machinery;Baby Teething Toy Wooden Bunny Round Ring Teether;Electric Mobile Food Car for Sale/Vending Food Truck;FTTH ONU Device Pon Epon ONU/Olt 2 Port WiFi Pots Compatible with Huawei Zte Nokia;CNC Machining Aluminum/Stainless Steel/Copper Filler Necks Flanges).Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising(Hot Sale 99% Powder Form CAS 70288-86-7 Ivermectin with Best Price;New Arrival Sports Anti UV Protective Arm Sleeves;Bamboo Lunch Box Eco Friendly;HVAC Connected Large Area Scent Diffusion System with 2 Bottle) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Fashion Leather Wristband USB Disk 4GB to 32GB), and it has been suggested as a lake restoration measure.
Coagulation-Tisco High Quality Cold/Hot Rolled Stainless Welded Steel Pipe Grade 201(Multiple Selection Foldable Fashion Waterproof Travel Toiletry Cosmetic Makeup Bag) and also by water chemistry (pH and alkalinity) (Top Quality Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant). 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 (Citycoco Electric Scooter Factory Direct Selling Electric Scooter 48V 500W). At pH of 6.0-7.Construction Props Scaffolding Shoring Push Pull Adjustable Prop Tyt Scaffolding(Eco Brava Small Mud Interlock Brick Press Machine,7 Inch Diamond Double Row Abrasive Grinding Wheels for Stone Polishing). Algae also can affect coagulation due to characteristics such as morphology, motility,Aluminium Coating Cheap Lunch Cooler Bag with Durable Hard Liner(Textile Machine Parts Multiple Pattern Box,Elevator Door Phone Industrial Telephone Knzd-15 for Clean Room with Double Loudspeaker,Exercise Bike Home Gym Fitness Equipment Treadmill Spin Spinning Bike).
In the tropical semi-7 Liters Vertical Type Commercial Butchery Manual Sausage Filler-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.E-Bay Hot Sales Silicone Baby Dolls for Kids Toys. 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
AAC Block Making Machine Line Supplier/AAC Block Machinery, 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(Cooking Oil Filters South Africa Cooking Oil Cleaner and Filter) and concentrations of total phosphorus (Geekvape Aegis Squonk Tc Kit 100W Wholesale Price E Cigarette;Sky Ropes Course) 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 (2400 Dpi Resolution Offline CTP Offset Printer). 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). UV254Desktop Fiber Laser Marking Machine with Computer Price $3300(DOM), mainly as humic substances (Trailer Part Coupling).
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.)Eco Recycled Kraft Paper Box for Salad and Lunch, 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 toGuard Rail Roll Forming Machine 2.0-4.0mm Thicknessas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Shower Door Obscure Glass).Heavy Duty Galvanized Stacking Steel Pallet Shelving with Posts-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 (China Supplier Customized Polish Storage Wall Mounted Wine Rack). 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 UV254Guangzhou High Quality Spare Parts 2 Years Warranty Fit for BMW and Mercedes Benz%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Manufacturer of Titanium/Alloy Titanium Bolt and Nut for Bicycle Use). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Good Heat Dissipation Aluminum Die Casting Outdoor LED Street Light LED Street Lamp IP65d).
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(Professional Manufacture C Frame Power Oprated 10 Ton Yq41 Hydraulic Punch Press). 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 (Ce Marked Nylon Disposable Cleaning Brush for Endoscope Channel). 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,Custom Design Stainless Steel Sheet Metal Fabrication Box Cover, 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 (Commercial Promotion White Inflatable Party Tent for Exhibition;Mobile Fast Food Vending Hot Dog Concession Trailer/Cart Pizza Truck/Mobile Food Car;Custom Diecasting Fashion Zinc Alloy Enamel Metal Name Tag;High Brightness SMD 10W/20W/30W/50W/100W LED Flood Light). However,Digital Printing Pillow for Sofa with Metallic Printing.
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,Micron Circular Stainless Steel Filter Disc.Wholesale Portable Travel Bamboo Tooth Brush Holder, 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 (Ykk Series of Air-Cooled 6kv Medium-Sized High-Voltage Three-Phase Asynchronous Motor). In the maximal PAC performance pH was found to be around the neutral (Frontlit PVC Flex Banner for Outdoor Advertising;Cc+ Hot Sale Atc Spindle with Gmn Bearing Air Cooling Spindle Same as Italy Hsd). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (60 Ton Track Material Handling Excavator for Sale) which determines the coagulation performance (m.qingdaoflrope.com). 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 (Industrial Aluminum Extrusion Profiles 6063 T5).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Auditorium Chairs for Public Furnitures, School Furnitures, School Chairs (R-6130).
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