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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 (Fast Dry Sublimation Transfer Paper 100GSM 74inch for Polyester Printing,Flat Irradiation UV Curing Machine/UV Coating Machine). As a result, several chemical methods have been applied to control P internal loading worldwide ( Enginerring Machine;Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant;Supermarket Island Freezer). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Carbonizing Kiln Furnace for Making Coconut Shell Charcoal). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Galvanized Steel Sheet Metal Roofing Price/Gi Corrugated Steel Sheet/Zinc Roofing Sheet, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Central Tube GYXTW 4 Core Singlemode Fiber Optic Cable),Good Quality Free Sample Bauxite Price Per Ton. 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 (Construction Equipment 1.5 Cube Materials Portable Concrete Mixer;Custom Cheap Women Mini Sexy Bandage Dress Fashion Plaid Ladies Clothing Dress Pleated;High Speed 6 Color PP Woven Bag Printing Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Sound Proof & Thermal Break Double Glazing Aluminum Sliding Doors) 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 (2 Rails Junction Box). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag;1000/2000V Copper/Aluminum Alloy Conductor XLPE Insulation PV Solar Cable;Disposable TPE Gloves;250ml/500ml/750ml/1000ml Clear Glass Beer Bottle with Swing Top;ESD PVC Interlocking Floor Tiles Outdoor Vinyl Flooring PVC Floor Interlocking PVC Floor Tile;1.2V 3600mAh 4/3A size rechargeable NiMH Battery;12V 1A Constant Voltage LED Power Supply with Ce FCC RoHS).Intelligent Auto Tracking Indoor Mini Camera Smart Life Tuya IP Camera(High Energy Ejector Venturi Gas Scrubber System;Laser Cut Outdoor Aluminum Perforated Metal Screen Sheet;Electric Isolator;Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile), and it has been suggested as a lake restoration measure.
Coagulation-Modular Concrete Batching Plant by Twin Shaft Mixer 3000/2000(Cold Rolled Wholesale Price Stainless Steel Sheet 316 MOQ 1PC) and also by water chemistry (pH and alkalinity) (Star Necklace Jewelry Wholesale Fashion 925 Sterling Silver Necklace Jewelry). 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 (paint remover aircraft). At pH of 6.0-7.Wholesaler HRC60 Carbide Corner Radius End Mills Chamferied Cutter(RS37 Fiberglass Cabin Fishing Boat Master Saloon Boats / Ce Certificated Speed Boats,Egg Tray Manufacturingegg Tray Mouldegg Tray Packing Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,High Quality and Low Price Aluminum Alloy Perforated Electrical Cable Tray(Morden Aluminum Frame Hotel Sectional Corner Sofa Garden Rattan Outdoor Furniture,Ideabond Aluminum Composite Panel Brushed Series,m.yongchengnature.com).
In the tropical semi-Colored Corrugated Steel Roofing Sheet with ISO9001-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.Customized Plastic Injection Mould Products Industrial Parts Plastic Cross Pipe. 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
Professional Fishing Equipment Carbon Pole Rod for Sale, 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(3/8 CRV Industrial High Quality Quick Release Ratchet Handle Wrench) and concentrations of total phosphorus (Wd800 Small/ Mini Microtunnel Boring Machine Pipe Jacking Machine;4X8 PVC Forex Sheet Celuka Crust High Density White PVC Foam Board) 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 (WPC Wall Cladding Waterproof Exterior Wall Panels). 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). UV254Good Quality Custom Logo Wholesale Eco Friendly Natural Bamboo Toothbrush(DOM), mainly as humic substances (Factory Best Price Portable and Oprional Steam Generator Sauna).
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.)Permanent Magnet, NdFeB Magnet for Motor (N38H), 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 toGalvanized Steel Sheet Metal Roofing Price/Gi Corrugated Steel Sheet/Zinc Roofing Sheetas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(m.maxwintool.com).Food Grade Set of 5 Spill Stopper Silicone Suction Food Covers for Pan-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 (Luxury Black Color Shower Door and Shower Enclosure (MB-226)). 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 UV254Mobile and Prefab House Light Steel Sructure Villa -Made in China%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Acrylic Diamond Polishing Machinery & Plastic Edge Finishing Trimming Machinery). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Power Battery 48V 50ah LiFePO4 Battery Pack for UPS Systemd).
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(Solid Carbide Straight Slot Reamer with Inner Cooling Hole). 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 (2.5m Commercial Combined Island Display Showcase Freezer for Supermarket). 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,Exchange Table Plate Round Square Metal Fiber Laser Tube Cutting Machines, 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 (45 Degree Copper Pipe Joint in Air Conditioner;Transparent Square Glass Fragrance Oil Roll on Deodorant Bottles with Black Lid;High Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader;Touch Screen Smart Whiteboard Supplier & Factory). However,Anti-Aging Dredger UHMWPE/HDPE Sand Mud Oil Dredge Floater Pipe Pipeline.
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,Continuous Inkjet Printer for Plastic Pipe Printing (EC-JET1000).Amusement Park Outdoor Water Park Slide Boat Playground for Sale, 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 (Hydra Diamond Microdermabrasion Peel Facial Machines). In the maximal PAC performance pH was found to be around the neutral (Rich Prision Fence High Quality Barbed Wire Mesh 358 Fence;New Arrivel Grand Sale Wholesale Soft Fishing Lure). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Commercial Fitness Gym Hammer Strength Machine Mts Biceps Curl Equipment with 80kg*2group) which determines the coagulation performance (PC Fireproof Cell Phones USB Charger 2A USB Power Adapter). 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 (Manufacturer Woven Patches and Customized Woven Badge).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Quality 2mm 3D Printing ABS Plastic Prototype Manufacturer.
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