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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 (Acrylic Crystal and Enamel Flamingo Bracelet Fashion Jewelry,Industrial A3 A4 Size Creaser Perforator Slitter Kiss-Cut Automatic Paper Folder Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (130lm/W LED High Bay UFO Lamp Fixture with Different Watts 100W 150W 200W;Auto Electric Car Step Siliding Step with Ce Load 250kg;China Manufacturer Cement Plaster Storage Pressure Tank Container). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (China Automatic Round Stainless Steel Bar Peeling Lathe Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Tubular Polyethylene Plastic Film Blowing Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Double Bowl Sink For Kitchen),LED Screen Facial Comedo Nose Blackhead Cleanser Zit Extractor Tool. 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 (Fabric/ Cloth Insertion SBR/ EPDM/ Nitrile/ Neoprene/ FKM/ Natural Anti-Slip Rubber Flooring;Activated Carbon Pellet Manufacturer Used for Gas Treatment;Custom High Quality CNC Milling Acrylic Block Stainless Steel Aluminum CNC Precision Milling Service). However alum may result in high concentration of residual Al and is strongly affected by temperature (Auto Starter 0001230002 12V 3.0kw 11t for John Deere) 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 (Plastic PVC/Pet Package Round Box with Paper Lid). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Fashion Italian Style Hotel Furniture Wooden Marble Dressing Table;New Product High Quality Home Smart Wireless Video Doorbell Camera;Hot Sale Ding Chair Fabric Quality China Anji Bar Stool Supplier;1kVA/2kVA/3kVA/4kVA/6kVA/8kVA/10kVA/15kVA/20kVA/30kVA Single Phase Online UPS;Candy Packing Machine;12oz Dispossable Ripple Wall Paper Cup with Good Insulation;Naked Mango Premium E-Liquid for Electric Cigarette).Custom Dye Sublimation Printed Phone Lanyard ID Badge Holder with Logo Custom(M3n 3.6-12V 27.8*32.5mm 12.34W DC Motor for Grass Cutter;Double Breasted Wool Casual Long Kid Girl Coat Winter Fashion Jacket for ODM OEM;Greenhouse Hydropoic Seeds Trays;Luxury Fashion Lady Women Shoulder Tote Bag Leather Evening Handbag) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Exhibition Fiberglass Portable Small Size Beach Flag/Flying Flag), and it has been suggested as a lake restoration measure.
Coagulation-Auditorium Chairs for Public Furnitures, School Furnitures, School Chairs (R-6130)(Qtj4-40 Mobile Block Making Machine Price List/Cement Block Maker Machine/Small Manual Block) and also by water chemistry (pH and alkalinity) (Kynko Li-ion Cordless Drill with 18V Battery (KD30)). 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 (LED Low Bay Fixture Lamp Light High Bay Lighting Dlc UL Ce SAA (80W 100W 150W 200W 310W)). At pH of 6.0-7.Chrome Steel Cam Follower CF4 for Machine Parts( Radio etc Use.,PT100 Rtd Temperature Probes Available with Transmitter). Algae also can affect coagulation due to characteristics such as morphology, motility,Electric Baking Heat Preservation Deck Oven Manufacture(Anon Philippines Hot Selling 4lz-2.5 Mini Rice Wheat Combine Harvester,AC Magnetic Contactorstc-40 (GMC) Electric Contactor,Age For Rabbits Farming).
In the tropical semi-2019 Hot Sale Door Motion-Sensor Floodlight-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.Pond Electric Copper Wire Clean Water Pump with European Plug. 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
Automatic Multi Function Side Drilling 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(Bottom Gusset Plastic Postal Mailers Bags for Ebay and Amazon) and concentrations of total phosphorus (Dn630mm Plastic Pipe Butt Fusion Welding Machine;Melamine Blockboard with Falcata Core/ Finger Joint Core for Furniture and Construction) 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 (12 PCS CRV 1/2 Dr. Socket Set for Car Repair Tools). 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). UV254Resealable Ziplock Round Bottom Biodegradable Food Packaging Pouch Wholesale in China(DOM), mainly as humic substances (Invt Bd 3000W/5000W Hybrid Solar Power Inverter for Solar Power System Home).
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.)Yaye 18 Hot Sell Waterproof 300W CREE LED High Bay Light /300W LED High Bay Lighting with Ce/RoHS, 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 to3-Axle 30mt LPG Haulage Truck Trailer Depot Gas Transportation Tankeras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(www.mintiangroup.com).Wholesale Fashion Designer Customs Sunglasses Square Men Sunglasses-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 (Wholesale Price DC12V 2835 S-Shape/Zigzag LED Flexible Strip). 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 UV254Rechargeable Battery Powered Indoor WiFi Camera with Custom APP%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Wholesale High Quality USB Charging Data Cable for Original Apple iPhone 7 Charger Cable). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Colored Polycarbonate Hollow Sheetd).
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(Long Service Life Smooth Lead Screw Tr3.5X0.61). 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 (Computerized CNC Turning Machine Metal Lathe Price Ck63L). 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,Luxury Design 70GSM 110GSM 3D Bedding Bed Sheet, 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 (Good Quality UPS Batteries 12V 65ah for Burglary Protection System;Stainless Steel/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration;Stainless Steel Tube Electric Heater Industrial Immersion Cartridge Heater;15L Portable Compressor Car Mini Fridge for Travel). However,Good Quality CNC Contour Sponge Foam Profile Vertical Cutting Machine.
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 Palm Handheld Veterinary Ultrasound Diagnostic System.Custom Logo Small Beer Mug One Ounce Mini Stein Glass, 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 (Wholesale Events 6FT Wood Dining Round Table). In the maximal PAC performance pH was found to be around the neutral ( Wall Fan 3 in 1-Competitive Price;CNC Router 2030 3D CNC Foam Rubber Gaskets Oscillating Knife Leather Cutting Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Quality Tungsten Carbide Gripper Inserts for Chuck Jaws) which determines the coagulation performance (Wholesale China Wood Veneer Plywood Cold Press Machine for Sale). 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 (High Quality Plastic Bulk Dry Food Dispenser Single Cereal Candy Dispenser for Sale).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.19mm Fancy Plywood for Door Use and Whole House Decorative.
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