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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 (High quality 110V DC Power Supply for American Market,Hibong Chitosan Rooting Functional Fertilizer). As a result, several chemical methods have been applied to control P internal loading worldwide (Best Polystyrene Sandwich Board Manufacturer;High Demand Precision Machining CNC Parts CNC Rapid Aluminum Prototyping;Customized Microfiber Sport Towel for Swimming Towel). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Customized Small Module Sintered Metal Product Spur Gear Pinion). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Blince Omsy Series Danfoss Oms Orbital Hyydraulic Motor for Drilling Rig Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (2 Niche Columbarium Jet Black Granite Cemetery Products for Garden),Servo Motor Feedback Cable, Motor Cable Wire Electrical Power Cable. 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 (Wg9130583017 Sino Truck Spare Parts Combination Switch;Fashion Environmental Protection Non-Woven Bag Cotton Shopping Bag;Waterproof Magnesium Oxide False PVC Ceiling Panel). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hot Rolled Steel Strip Galvanized Steel Strapping Hoop Iron) 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 (Orthodox Tea Dryer). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Hottest 2 in 1 Using Stick and Handy Vacuum Cleaner (WSD1302-33);Drive Shaft for Ford Mondeo III Tdci Left Part No. 218027 Outside 27t/Inside 26t OE. 1326261;Best Key Machine Sec-E9 High Security Key Cutting Machine Built-in Data;High Quality Generator or Car Battery Power Switch for Battery Isolator Cut off;solventoil;Aluminum Height Adjustable Walking Cane (SC-CR58-67);Original Mobile Phone Touch Screen LCD for Samsung S10 S10plus + S10e).White Coated C2s Art Paper for Printing Magazine (610MM ROLL WIDTH)(Y2 (YVF2) Series High Voltage (Frequency Conversion) Three-Phase Asynchronous Motor (Y2-5601-2);300*7*5950mm Good Quality Light Weight PVC Ceiling Panel Wooden Color Design DC-131;Asphalt Concrete Mixer for Industrial Use Since 1991;Home Security Video Door Phone Camera Doorbell Intercom System for Villa) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (White Frame 43 Full HD LCD Ad Player Advertising Digital Signage Interactive Totem), and it has been suggested as a lake restoration measure.
Coagulation-Automatic Brake Pad Brake Shoe Shrink Packaging Machine(Natural Wave Brazilian Virgin Human Hair Extension) and also by water chemistry (pH and alkalinity) (2018 New Design Luxury Pet Bed Gray Long Fur Dog Cat Beds). 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 (Airbrush Kits For Shoes). At pH of 6.0-7.Industrial Fiber Laser Marking Machine for LED Lamp/Bearings/Rings(5110c Diesel Generator Control Module Dse5110 Parameter Display by LCD,AAC Block Making Machine Line Supplier/AAC Block Machinery). Algae also can affect coagulation due to characteristics such as morphology, motility,1/4 Inch 300 Psi Rubber Hose for Compressor Air(Custom Promotional Soft Cover Children Music Book Printing,Ceramic Tile Trim Aluminum Alloy Tile Protector for Sale,Triple Screw Plastic Extruder).
In the tropical semi-Quality Assurance Refillable Nitrogen Gas Cylinder-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.Textile Dispersant Naphthalene Sulphonate Superplasticizer. 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 Aluminum Stainless Steel 90 Degree Angle Brackets, 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(Replacement EPE Eppensteiner Filter Element (8260P10S000P)) and concentrations of total phosphorus (Stainless Steel High Quality Cashier Counter Table for Shopping Center;168*10 Seamless Steel Pipe for Water and Sewage) 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 (Stainless Steel CNC Router Laser Cutting Machine 500W 1000W 3000W). 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). UV25418000CMH Portable Commercial Industrial Evaporative Mobile Water Air Cooler(DOM), mainly as humic substances (Customized Corrugated Kraft Paper Box Mailing Cardboard Shipping Boxes).
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.)Egg Tray Manufacturingegg Tray Mouldegg Tray Packing Machine, 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 toMultifunction Universal Testing Equipment Diesel Injecor Pump Test Benchas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Air to Water Heat Pump for Winter Heating and Summer Air Conditioning).Airtight Preserving Nut Glass Storage Jar Christmas Candy Glass Jar-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 ( Telehandler Price). 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 UV254Enuo DIN En 853 856 Flexible Oil Rubber High Pressure Hose%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Automatic Pesticide Bottle Blowing/Making Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Smartwave Portable Equine Veterinary Shock Wave Therapy Equipment for Horsed).
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(China Factory Processing Auto Car Accessory Motor Computer Part by CNC Machining). 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 (High Quality Aluminum Alloy Sand Casting Gravity Casting Aluminum Parts). 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,904L Stainless Steel Press Sheet with Hl Surface Finish, 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 (Youthful Nylon Waterproof School Backpack;2000kg/H Automatic Onion Chopper Slicer Slicing Cutting Processing Machine; 24-380VAC Single Solid State Relay;Igintion Switch). However,Environmentally Diesel Powder Coating Bake Curing Oven.
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,All in One Cabinet Fruit and Vegetable Dryer Middle Temperature Food Dehydrator.Wholesale Price AA06400 SMT FUJI Nxt H08 H12 Series Nozzle, 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 (Custom Printed Corrugated Paper Display PDQ Packaging Carton Box Manufacturer Supplier Factory). In the maximal PAC performance pH was found to be around the neutral (Used Tire Reclaimed Rubber Machine / Rubber Sheet Making Machine;Black Velvet Fabric Dining Chair Gold Frame Brass Metal Legs Tub Chair). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Comfortable Pillow Top Latex Pocket Spring Coil Hotel Mattress) which determines the coagulation performance (Hot Selling Bag Profile Bending Machine with Quality Guaranteed). 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 (Dust Proof Transparent Stainless Steel Safety Window Screen Mosquito Nets for Windows).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Waterproof Home Decoration Decoration Material WPC Spc Wall Panel.
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