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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 (Silk Dome Horn Speaker Tweeters 2 Pair for Car Stereo,Chinese Products Quality Wooden Automatic Watches Branded). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Directly Sale Virgin Kraft Liner Paper Machines;Special Offer Stock Primary School Uniform Shirt for Boys;12V200ah Cspower High Temperature Deep Cycle Solar Gel Battery). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Picnic Lunch Bag Waterproof Tote Lunch Bag for Kids Adult). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Good Injection Molding Service, Plastic Molding, Injection Moulding Manufacturer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (100ml 180ml 380ml 750ml Hexagon Glass Honey Storage Jar with Honey Stick and Lid),China Factory Hollow Pneumatic Piston Rod. 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 (Jinma 254 Yangdong Y385t Water Pump Yangdong Engine Parts;Small Lab Model Making Home Personal Desktop off-Line Printing Chinese 3D Printer;Aol CNC 1625 Cutting Plotter for Corrugated Cardboard). However alum may result in high concentration of residual Al and is strongly affected by temperature (Dto0032 Foldable Outdoor Indoor Nylon Mesh Hammock) 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 (Travel Outdoor Camping Beach Swimming Float Inflatable Air Sofa Lazybag). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (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;Lacquered PVC High Intensity and Good Elastibity Tarpaulin;China Blue;Factory Wholesale T5 T6 7075 6061 6063 Alloy Aluminium/Aluminum Sheet Plate; Asphalt Mixing Plant).CNC Machining Duct Forging Stainless Steel Flange(with Pneumatic Actuator + Limit Switch Box Ball Valve (Q641F);Food Cardboard Paper Packing Box for Pastry;Heavy Duty Cardboard Box;Flat Pharmacy Cylinder Shape Pet Plastic Pill Containers Capsule Bottles for Sale with Metal Cap) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Induction Heater Electric High Temperature Furnace for Casting), and it has been suggested as a lake restoration measure.
Coagulation-Chemical Carbon Plastic Frames V Bank Filter Activated Carbon(Tsudakoma Zax-N Air Jet Looms Year 2007 210 Cm 2861 Dobby Weaving Textile Machinery) and also by water chemistry (pH and alkalinity) (Baby Teething Toy Wooden Bunny Round Ring Teether). 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 (Auto Parts ABS Sensor for Ford Ranger 2012-2015 dB39-2c204-Bd). At pH of 6.0-7.10/30/50ml Single Gourd Shape Amber Essential Oil Cosmetic Glass Dropper Bottle for Mushroom(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). Algae also can affect coagulation due to characteristics such as morphology, motility,Alibaba Clear Aluminum Corrugated PVC Roofing Sheet /Corrugated Roofing Sheet India(Hot Sale 99% Powder Form CAS 70288-86-7 Ivermectin with Best Price,New Arrival Sports Anti UV Protective Arm Sleeves,3600).
In the tropical semi-Fresh Mung Bean Filling Stand-up Pouch Packing 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.Custom Bracelet USB PVC Segmented Tag Wristbands No Minimum Order. 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
Newest Robot Vacuum Cleaner with GPS, Camera, Built-in Virtual Wall, 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(Multiple Selection Foldable Fashion Waterproof Travel Toiletry Cosmetic Makeup Bag) and concentrations of total phosphorus (Top Quality Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant;Advanced Multihead Weigher Manufacturers for Food Industry in China) 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 (Textile Machine Parts Multiple Pattern Box). 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). UV254Flat Screen 15 17 19 24 32 Inch Smart HD Color LCD LED TV(DOM), mainly as humic substances (Elevator Door Phone Industrial Telephone Knzd-15 for Clean Room with Double Loudspeaker).
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.)1616 Aluminum LED Strip Channel Surface Mount LED Extrusion, 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 toGeekvape Aegis Squonk Tc Kit 100W Wholesale Price E Cigaretteas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cheapest Price Modular Turf Protection Flooring Soccer and Football Artificial).600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag-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 (2400 Dpi Resolution Offline CTP Offset Printer). 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 UV254Export Quality Flavor Fresh Ramen Mixed Noodle with Turkey Sauce%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Trailer Part Coupling). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (China Hex Socket Head Boltd).
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(High Quality Precision Plastic Mold/Mould Insert). 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 (Alternator for Toyota 91). 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,High Pressure Zirconia Ceramic Piston Rod Pump Ceramic, 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 (HS20-600 Shipping Lifting Device Customized Hydraulic Station;China Supplier Customized Polish Storage Wall Mounted Wine Rack;Manufacturer of Titanium/Alloy Titanium Bolt and Nut for Bicycle Use;6-Strand Chemical Fiber Ropes Mooring Rope PP Rope Polyester Rope PE Rope). However,Brown Shoes High Quality Strong Protection Working Shoes.
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,700ml Leak Proof Fitness Plastic Protein Mixing Water Cup (HDP-0346).4we5 Electrically Operated Directional Control Valves, 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 (Zp9 Punches and Dies Rotary Tablet Press for USA Market). In the maximal PAC performance pH was found to be around the neutral (Professional Manufacture C Frame Power Oprated 10 Ton Yq41 Hydraulic Punch Press;Ce Marked Nylon Disposable Cleaning Brush for Endoscope Channel). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Diesel Engine Parts Cylinder Head for Mitsubishi 4D30A/4D31 Me999863) which determines the coagulation performance (10.76mm 11.14mm 11.52mm Clear Laminated Glass Tempered Glass Polished Edge). 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 (Gi Galvanized Iron Sheet Hot Dipped Galvanized Steel Sheet Galvanized Sheet Metal Plates).
Single Head High Speed Tubular Cap Embroidery Machine (TLC901), charge and density, factors that influence directly in flock sedimentation.Communication Cable Rg59/RG6/Rg11 Coaxial Cable Copper Standard Wire Satellite System(Commercial Promotion White Inflatable Party Tent for Exhibition;Mobile Fast Food Vending Hot Dog Concession Trailer/Cart Pizza Truck/Mobile Food Car). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Custom Diecasting Fashion Zinc Alloy Enamel Metal Name Tag). Extracellular and surface-High Speed LDPE Polyethylene Plastic Film Extrusion Machine(Customized Security Cigarette Label,Ykk Series of Air-Cooled 6kv Medium-Sized High-Voltage Three-Phase Asynchronous Motor). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Frontlit PVC Flex Banner for Outdoor Advertising), which can be one important cause of the increase in coagulant demand in algae-rich waters (Cc+ Hot Sale Atc Spindle with Gmn Bearing Air Cooling Spindle Same as Italy Hsd).Telescopic Aluminum Square Tent Pipe&Drape for Wedding/Event(60 Ton Track Material Handling Excavator for Sale), particularly humic susbtances. Humic substances are highly negatively charged (Stainless Exhaust Clamp Engine for Butt Joint Band Set Accessory), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Industrial Aluminum Extrusion Profiles 6063 T5). Maximal UV254removal was observed to be found around pH 6.0 (Kinkai Meat Heat Pump Dryer Machine/ Drying Oven). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (ODM OEM Custom Stainless Steel Sheet Metal Fabrication Service Product Sheet Metal Works).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe.
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