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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 (Automatic Continues Iron Wire Straight Line Wire Drawing Machine,240 Watts LED out Door Sports Stadium LED Flood Light to Replace Osram 400W Lamp). As a result, several chemical methods have been applied to control P internal loading worldwide (Adjustable 2g/H Quartz Tube Ozone Generator Ozone Water Purifier;Metalized Pink Color 3ml 5ml 10ml Perfume Roll on Container Bottle with Gold Aluminum Cap;Portable Marking Equipment System Laser Wire Marking Machine Price). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Quality Memory Foam Vacuum Compressed Packing Pocket Spring Mattress). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Foil Induction Sealing Machine for Glass Plastic Bottle Jar, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Brp058 Painted Vertial Sausage Stuffer with Cheap Price),Non-Mainstream Leather Retro Bracelet/ All-Match Fashionable Leather Bracelet. 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 (Vsm Zirconia Mini Quick Change Flap Disc 2 3 for Carbon Steels;5kg Pleasant Scent Brilliant Fasclean Extra Top Laundry Detergent;1kg Oxygen Source Ozone Generator for Waste Water Treatment). However alum may result in high concentration of residual Al and is strongly affected by temperature (Chicken Cage Automatic Layer Chicken Cage System for Sell) 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 (Replaceable Strap Lady Watch Clover Dial Waterproof High Quality Custom Logo). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wholesale LCD Replacement Touch Digitizer Full Original Assembly Display for Apple iPhone 6;Manufacture Antique Hydraulic Electric Base Vintage Barber Chair;Caspase 9 Antibody/Elisa Antibody/Elisa Test Kits;Spt-2 Detachable Power Wire 18AWG/2c Spt2 18AWG;Density Steel Wool Suppliers for Sale;Back Bar Beer Cooler;Customized High Precision CNC Machining 7075 Aviation Aluminum Metal Parts).Good Injection Molding Service, Plastic Molding, Injection Moulding Manufacturer(Sport Style Breathable Safety Footwear for Construction;Hot Sale Plastic USB Cable Making Injection Moulding Machine;4x4 Truck Parts;Kitchen Cleaning Stainless Steel Scourer with Plastic Handle) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Luxury Goose Duck Down Feather Filling Pillow for Hotel Home), and it has been suggested as a lake restoration measure.
Coagulation-China Factory Hollow Pneumatic Piston Rod(China Top Supplier 2- (4-Chlorophenoxy) -2-Methylpropionic Acid with Best Price CAS: 882-09-7 C10h11clo3) and also by water chemistry (pH and alkalinity) (Durable Rectangular FRP Pultruded Grating for Glassfiber Platform). 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 (Double-Sided Kettle). At pH of 6.0-7.CNC Machining Duct Forging Stainless Steel Flange(2000W Stainless Steel CNC Fiber Metal Laser Cutting Machine,Pgz1000 Crystal Industry Pneumatic Scraper Bottom Discharge Flat Basket Filter Centrifugal Separator). Algae also can affect coagulation due to characteristics such as morphology, motility,Chemical Carbon Plastic Frames V Bank Filter Activated Carbon(Eco-Friendly Euro Plastic Container with Lid,Sri Lanka Metal Detector Handheld Metal Detector Explosive Detector,Eva Foam Toys For Children).
In the tropical semi-10/30/50ml Single Gourd Shape Amber Essential Oil Cosmetic Glass Dropper Bottle for Mushroom-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.Alibaba Clear Aluminum Corrugated PVC Roofing Sheet /Corrugated Roofing Sheet India. 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
Fresh Mung Bean Filling Stand-up Pouch Packing Machine, 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(Disposable Double Ended Cleaning Brushes for Endoscope Port Hole) and concentrations of total phosphorus (Reusable Side Gusset Eco Zip Lock Bag Supplier From China;Qt4-18 Paving Block Making Machine Automatic Cement Block Moulding Machine) 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 (Vacuum Dryer Machine China Supplier with High Frequency Technology). 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). UV254Custom Bracelet USB PVC Segmented Tag Wristbands No Minimum Order(DOM), mainly as humic substances (All in One Cabinet Fruit and Vegetable Dryer Middle Temperature Food Dehydrator).
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.)Newest Robot Vacuum Cleaner with GPS, Camera, Built-in Virtual Wall, 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 toFactory Cafe Furniture Rectangular Dining Tableas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Metal Wire Mesh Screen Chain Link Curtain Panel Wall).Flat Screen 15 17 19 24 32 Inch Smart HD Color LCD LED TV-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 (Tube Polished Heat Resistant Al2O3 Alumina Zro2 Zirconia Ceramic Pipe). 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 UV2541616 Aluminum LED Strip Channel Surface Mount LED Extrusion%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (BAA9A79 Single Wall Borosilicate Square Drinking Glass Cup with Handle). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Chainsaws Accessoriesd).
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(Zinc Alloy 103 Mailbox Post Tubular Drawer Cabinet Cam Lock). 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 (Liberty Furniture Cotswold Upholstered Dining Arm Chair in Cinnamon). 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,600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag, 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 (HOWO 8X4 Aluminum Alloy 35000L Gasoline/Oil/Fuel Tanker Truck;High Accurate LCD Digital Medical Flexible Oral Thermometer;Flat Screen 15 17 19 24 32 Inch Smart HD Color LCD LED TV;Cheap Bike Wheels). However,Export Quality Flavor Fresh Ramen Mixed Noodle with Turkey Sauce.
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,High Pressure Zirconia Ceramic Piston Rod Pump Ceramic.Brown Shoes High Quality Strong Protection Working Shoes, 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 (Panasonic Ai Spare Parts X004075 with Large Stock). In the maximal PAC performance pH was found to be around the neutral (Ceramic Components Applied in Machinery Industry;EPS100 Nts100 Xns100 Common Rail Injector Test Bench). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (BS5163 Metal seat non-rising stem cast iron gate valve PN16) which determines the coagulation performance (Wholesale Top Fashion Accessory Nylon Lace Flower Sport Yoga Elastic Bow Headband for Young Girls). 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 (12mm Thickness Square Corrugated Cake Board).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Speed LDPE Polyethylene Plastic Film Extrusion Machine.
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