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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 (90L 4 Drawers Dry and Safety Case Desiccator Cabinet for Equipment Storage,Aluminum Handle Squeegee Blade). As a result, several chemical methods have been applied to control P internal loading worldwide (SMC / BMC Compression Molds and Molded Parts From China;800g ECR Glass Fibre Plain Woven Roving 800GSM for Munal Boats Buildings;High Quality Low Price Square Pipe CNC Plasma Cutting Tool). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (USB Powered UV LED Photocatalyst Electric Bug Zapper Mosquito Killer). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,10m 3.5mm Male to Female Audio Cable for iPhone iPod, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (100W 200W 300W 400W Small Wind Turbine Generator),Js500 Twin-Shaft Concrete Mixer for Block Machine. 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 (Wc67y Hydraulic CNC Aluminium Plate Rolling Press Brake/Bending Machine;Wholesale Fashion Custom Christmas Glass Jar Candle Holders with Lids;Customized Brand Cosmetic Magnetic Eyeliner with Mink Strip Eyelashes). However alum may result in high concentration of residual Al and is strongly affected by temperature (Silicone PU Ms Acrylic Sealant Adhesive Automatic Cartridge Filling Machine) 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 (Priced Cast Iron Double Balll Flanged Air Release Valve). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Tolerance Stainless Steel Stamping Parts Enclosure;3 Inch Smooth Corrugated PVC Suction and Discharge Hose;Custom Electronic Wire Harness with Jst Molex Housing Connector;Handsfree Car Kit Wireless Multipoint Speakerphone with Visor Clip;Peach Squishy;Factory Made Cheap Price Latching Circuit Relay for Power Control;Best Price 1325 Woodworking CNC Router Machine Equipment).40W Hot Sale Acrylic Ceiling LED Panel Light(100mm Thickness China Roof/Wall EPS Sandwich Panel From China Suppliers;High Efficiency Refrigeration Equipment Water Cooled Industrial Chiller;Factory Price Waterproof Interlocking PVC Wall and Ceiling Panels;6000 Series Alloy Customized Black Anodized Black Aluminium Extruded Enclosure) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (HDPE 1mm 2mm Plastic Strips /Tapes Manufacture for Decorate Christmas), and it has been suggested as a lake restoration measure.
Coagulation-Industrial Use Sandwich Panel Container for Offices/Construction Sites(Touch Screen Display Module Control Panel for Instrument) and also by water chemistry (pH and alkalinity) (Environmental Shot Peening Machine with Less Dust Emission). 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 (Vacuum Furnace). At pH of 6.0-7.OEM Foundry Factory Custom Aluminum Die Casting Products with CNC Machining(Roll up High Quality Luxury Comfort Spring Mattress,High Quality and Precision Chroming Zinc Plating CNC Machined Hardware for Medical Instrument). Algae also can affect coagulation due to characteristics such as morphology, motility,Custom Foldable Storage Basket with Metal Handle and Lid(A4 A5 Discoloration PU Leather Planner Agenda Diary Notebooks with Stamping Logo,PS126 Electric Automatic Surface Vortex Peripheral Motor Water Pump,Alcopla Aluminium Composite Panel).
In the tropical semi-Automatic Dry and Wet Pig Feeder for Pig Feeding Equipment-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.Vci PE Film for Ferrous Metal with Anti-Rust Performance. 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
Solar Garden Peacock Stake with Solar Light for outdoor Decoration, 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(18 mm OSB (Oriented Strand Board) for Roof Decking) and concentrations of total phosphorus (Ce Approved Acrylic Mini LED Letters Sign for Outdoor;16mm 15mm Wood Grain Melamine Glue Melamine Paper Laminated Plywood) 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 (New Design Infrared Touchless Automatic Sensor Electric Water Faucet). 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). UV254Carrier Roller for Sany Hydraulic Excavator Sy16-Sy850h-8(DOM), mainly as humic substances (Deutz-Fahr Haester Agriculture Combine Harvester 4yzp-4L for Wheat/Rice/Soybean/Corn/Graize).
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.)4.3 IPS Display 1080P Dash Cam 12 Mega Pixel Rear View Mirror with Parking Monitor, G-Sensor, 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 toChina Best Quality Goof Price Tpo Flat Roofing Waterproof Membraneas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(www.lowcled.com).China Top Supplier 2- (4-Chlorophenoxy) -2-Methylpropionic Acid with Best Price CAS: 882-09-7 C10h11clo3-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 (Women′s Knitted Acrylic Sweater Fashion Dress). 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 UV254Transparent Single Crystal Alumina Sapphire Jewel Bearing and Components%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (118 120 TV Tel Socket). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Embryo Slides Manufacturers Cheap Priced).
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(China Economic ASA PVC Corrugated Roof Sheet for Farm House). 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 (Key Chain Metal Key Rings Acrylic Key Bag Holder). 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,Handle Operation Flanged Lined PFA Butterfly Valve (D41F46), 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 (Pre Engineered Industrial Factory Prefabricated Light Steel Structure Building/Warehouse/Workshop;LCL Consolidation Shipping Freight From Guangzhou to Dayton;Yako Brass Waterproof Balcony Toilet Bathroom Floor Drain;Wall Mounted Brass Double Layer Corner Basket or Shower Basket). However,Plastic Filter/Plastic Mbbr Filter Media for Water Treatment/ Electric Kettle Filtration.
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 Quality Portable Deep Well Solar Pump Solar Water System.New Design Comfortable PU Cemented Men and Boy Sandal, 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 (Electric Commercial Ice Cream Cone Maker Ice Cream Waffle Cone Maker). In the maximal PAC performance pH was found to be around the neutral (Sc/APC Soc Splice-on Fiber Optic Quick/Fast Connector;Novel Designed Panel Steel Corrugated Metal Roofing Sheet Roll Forming Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Automatic Column and Boom Welding Manipulator Dlh) which determines the coagulation performance (iPhone 11 PRO Max Sublimation Blank 2D TPU Phone Case/Cover for Heat Transfer Printing). 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 (Dog Rain Jacket Especially for Outdoor Adventure with Harness Opening Easy on & off).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Popular Lifejacket EPE Foam Life Vest for Water Safety Equipment.
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