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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 (Long Range RFID Access Control Card for Non-Stop Parking,BOPP PE PVC PP Slitting and Rewinder Machinery). As a result, several chemical methods have been applied to control P internal loading worldwide (Used Cat Loader Caterpillar 966h Wheel Loader for Construction;Electronic Leak Detector Sf6 Gas Leak Detector So2 Analyzer;ASTM A335 P11 Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Stainless Steel Galvanized Perforated Metal Sheets). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,55kw 65kw Industrial Air Cooled Water Chiller Unit, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Custom Nylon Spandex Women Pants Blank Yoga Pants),Pre-Heated Copper Coil Pressure Solar Water Heater Equipment. 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 (Best Factory Price Metallic Honor Medal with Neck Ribbon;Water Play Equipment Inflatable Gym Air Track Mat;50 Bend PVC Pipe/Belling PVC Pipe/Making Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Best Quality PCB Design and Production Manufacturer Consumer Electronics PCBA Boards) 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 (White Melamine Paper Faced Blockboard /18mm Poplar Core Blockboard). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wall Mounted Bathroom Tissue Holder Toilet Paper Towel Roll Holder;Colorful Glass Straw Drinking Straw Reusable Borosilicate Glass;Silicon Carbide Mechanical Seal with Excellent Corrosion Resistance;Hot High Quality Self Service Car Wash Equipment;Kunststof Water PE Pipe Buis Voor Water / Gas Transport;Pedstal Electric Stand Fan 5 Speed Control Air Cooler;Manufacturers Sell Direct Bullet Design Red Hollow Crown Lipstick Tube).High Precision Mini Micro Button Load Cell(High Quality Asphalt Waterproof Emulsion Bitumen Emulsion Coating;Fashion Watch Factory Swiss Quartz Women Wrist Branded Watch (WY-001H);side table modern;Commercial Industrial Fast Food Chicken Electric Gas Pressure Deep Fryer for Mijiagao) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (20HP Copeland Scroll Compressor Zr250kce-Tw7-522), and it has been suggested as a lake restoration measure.
Coagulation-Cheap 20W/30W High Quality Fiber Color Wire Laser Marking for Metal Price(Prefab Prefabricated Lightweight Steel Structure Construction Processing Plant Metal Workshop) and also by water chemistry (pH and alkalinity) (Professional Industrial Cr-V Combination Plier for Cutting). 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 (Truck Crane 35 Ton). At pH of 6.0-7.PS126 Electric Automatic Surface Vortex Peripheral Motor Water Pump(Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type),Women Footwear Ballerina Casual Shoes With High Quality). Algae also can affect coagulation due to characteristics such as morphology, motility,Coating Precision CNC Auto Spare Machinery Parts Turning and Milling Industry(250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps,3*42mm Armoured NBR Sheathed Round Electric Submersible Oil Pump Power Cable,Air Compressor Polyurethane Hose with Quick Coupler).
In the tropical semi-Custom Logo Ceramic Tea Cup Porcelain Coffee Mug of Bd002-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.700mm RP HP UHP High Quality Graphite Electrode. 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
Linear Position Magnetic Position/Motion Sensor 150mm, 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(Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant) and concentrations of total phosphorus (Supermarket Island Freezer;Ab Roller For Sale) 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 (Custom Cheap Women Mini Sexy Bandage Dress Fashion Plaid Ladies Clothing Dress Pleated). 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). UV254Prime Quality Cold Rolled Steel ERW Tube Mill(DOM), mainly as humic substances (High Speed 6 Color PP Woven Bag Printing 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.)Fastener Screw /Self Tapping Screw / Machine Screw, 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 toDisposable TPE Glovesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Decorative Color Chips).Patio Outdoor Home Hotel Office Restaurant Aluminum Polywood Dining Table and 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 (12V 1A Constant Voltage LED Power Supply with Ce FCC RoHS). 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 UV254Men′s Polyester Moto-Boy Hunting Jacket Clothing%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Energy Ejector Venturi Gas Scrubber System). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Waste Paper Egg Carton Production Line Egg Tray Machined).
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(Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising). 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 (Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile). 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,Slotted Hex Head Self Drilling Screw with EPDM Washer, 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 (RS37 Fiberglass Cabin Fishing Boat Master Saloon Boats / Ce Certificated Speed Boats;Egg Tray Manufacturingegg Tray Mouldegg Tray Packing Machine;Morden Aluminum Frame Hotel Sectional Corner Sofa Garden Rattan Outdoor Furniture;Red Agate). However,20W Fiber Laser Marker/Engraver/Cutter for Metal Seal/LED Log/Anti-Dazzling Screen.
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,Professional Industrial Cr-V Combination Plier for Cutting.6.5HP Carrier 06dr241 Cold Room Compressor Refrigeration Unit for Fresh Storage, 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 (Ideabond Aluminum Composite Panel Brushed Series). In the maximal PAC performance pH was found to be around the neutral (Jarliet 140cm Big Breast Mini Sex Love Doll for Men Sex Masturbation;China OEM Cast Iron Tractor Farm Clutch Pulley). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (3/8 CRV Industrial High Quality Quick Release Ratchet Handle Wrench) which determines the coagulation performance (Bemo Roof Standing Seam Roof Panel Roll Forming Machine/Standing Seam Roofing Sheet Machine). 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 (Wd800 Small/ Mini Microtunnel Boring Machine Pipe Jacking Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Hot Sale Hospital Automatic Sliding Airtight Door.
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