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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 (Pink Strapless Dress Trumpet Sleeves Sweet Party Luxury Prom Dress,Domestic Air Conditioner Accessories Injection Molding). As a result, several chemical methods have been applied to control P internal loading worldwide (2017 Luxury Acrylic Double Jar White Jar for Cosmetic Packaging;High Speed Promotional Plastic Custom USB Flash Drive U016/Sy015;Home Furniture Metal Chair Grey Velvet Dining Chair). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Swing Check Valve Stainless Steel Type Non Return Valve). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,2019 New Arrival Original Adaptive Fast Adapter Rapid Wall Charger for Samsung S10, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Charming Opal Butterfly Sweater Chain Fashion Necklace Ornament),Lx85-9m Wheeled Digger Digging Height 6536mm 8 Ton Mini Wheel Wood Grabber. 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 (Dn100 4 Inch Rubber Seal 220VAC Wafer Type Electric Actuator Butterfly Valve;Auto Parts Belt Tensioner and Pulley OEM 0002021719 for W204 C250 Slk250;C1022A Bugle Head Coarse Thread Gypsum Board Screw 3.5*25mm). However alum may result in high concentration of residual Al and is strongly affected by temperature (KCD-108 Series for Home Appliance Colourful Rocker Switch) 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 (Bi-Metallic Composite Oilless Bush Sliding Bearing Custom Made Bimetal Bushing). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Quality Watermark Brass Square Bottle Trap in Gold;Stainless Steel Checkered Plate 304 316L 410 Floor Material;Snowkey Meat Processing Cooling Flake Ice Making Machine;Custom Aluminum Die Casting Parts for Medical Equipment;Semi Auto 5 Gallon PC Bottle Blow Molding Machine;Strong Baby Banquet Chair for Hotel/Restaurant/Wedding/Home;J5 6-24V 27.8*46.6mm 10.64W DC Motor for Grass Cutter).Fast Inflatable Air Bag Sofa Lounge Lazy Chair Bag Camping Bed Beach Hangout(2018 New Pet Supplier Warm Soft Canvas Flower Shape of PED Cat Dog Beds;Nylon Flashing LED Dog Leash with Night Light;Commercial Outdoor Picnic Table;Aluminium Spigot Lighting Truss) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Yiwu China Promotional Items Corporate Gift Hat Promotional Cap (C2032)), and it has been suggested as a lake restoration measure.
Coagulation-Factory Price Luxury Autism Heavy Duty Weighted Mink Blanket(Hypoallergenic Polyester Duvet Insert for Hotel Bedding (DPF17060) and also by water chemistry (pH and alkalinity) (Plastic Roofing). 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 (Ccec Chongqing Cummins Nt855 24V 6kw Motor Starter 3103914). At pH of 6.0-7.100% Fabric Advertising Display See Through Mesh Banner Windproof(Good Quality Tungsten Carbide Round Nose End Mill,Liyyou Ly17 Cord-Free Lithium Battery Stick Upright Vacuum Cleaner). Algae also can affect coagulation due to characteristics such as morphology, motility,Black Window Gable Boxes, 17*11*7cm Wedding/Baby Shower Favor Gift Box, Muffin Pastry Box(Automatic Food Canning Machine Tin Can Vauum Seamer,High Quality Big Power 40kw Hybrid Inverter for No Battery Backup Solar System,First Stage Feeder).
In the tropical semi-100mm Thickness China Roof/Wall EPS Sandwich Panel From China Suppliers-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.Stainless Steel Rectangular Pipes for Balcony Guardrail. 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
Jbz-22D Automatic High Speed Paper Cup Forming 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(Glossy Silvery Anodized Aluminium Profile for Windows and Doors) and concentrations of total phosphorus (Wd190V Handheld Metal Detector Gold Metal Detector Made in China;Factory Price Construction Material of EPS Metal Sandwich Wall Panel Roof Panel) 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 (Women′s Foam White Lettering-Print Cotton T-Shirt). 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). UV25410W Auto Oval Work Car Light Blue Red LED Forklift Warning Head Lamps(DOM), mainly as humic substances (ASTM A240 201 304 SS304 316/316L 310 Cold Rolled Stainless Steel Sheet).
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.)Flexible Plastic (PVC) Sheet with RoHS Standards (1mm-10mm), 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 toShinco Rechargeable Professional Bluetooth Wireless 8′′trolley Outdoor Speakeras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Marching Band Gloves With Velcros).Customized Mining Equipment with Drawing Design-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 Factory Anesthesia Apparatus Circuit Board PCBA Manufacturer One-Stop Assembly). 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 UV254Custom Jewellery 925 Sterling Silver Jewelry Diamond Stud Earrings%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Indoor Rubber Crumb No Odor Free Gym Rubber Tile). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (2019 Crop Top Sweat Suit Bulk 100% Cotton Custom Casual Sports Sweatsuit Women Tracksuitd).
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(Made in Malaysia Small Panasonic R134A Refrigeration Compressor (QB66)). 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 High Quality Stylish SMD LED Flood Light 10W 20W 30W 50W 100W 150W 200W). 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,Food Quick Freezing Machine Type Industrial Freezer IQF Fruit Freezing Tunnels, 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 (Metalized Pink Color 3ml 5ml 10ml Perfume Roll on Container Bottle with Gold Aluminum Cap;Portable Marking Equipment System Laser Wire Marking Machine Price;High Quality Memory Foam Vacuum Compressed Packing Pocket Spring Mattress;Humidity Regulator). However,Hight Quality Air Filter C1250 for Mann and Atlas Air Compress.
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,Industrial Paraffin Wax/Powder/Slab/Paraffin Wax Chemical Formula.Tri-Axle 50tons 60tons 18m Low Loader Lowbed Trailer Axles, 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 (Vsm Zirconia Mini Quick Change Flap Disc 2 3 for Carbon Steels). In the maximal PAC performance pH was found to be around the neutral (5kg Pleasant Scent Brilliant Fasclean Extra Top Laundry Detergent;1kg Oxygen Source Ozone Generator for Waste Water Treatment). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Chicken Cage Automatic Layer Chicken Cage System for Sell) which determines the coagulation performance (Tulipani Graphite Pillow Case). 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 (Wholesale LCD Replacement Touch Digitizer Full Original Assembly Display for Apple iPhone 6).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Bottle/Cup Electrical Tunnel/ Steam Tunnel for Shrinking Sleeve Labeling Machine.
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