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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 (Flanges Male Female Fittings Assembled with Flexible Metal Hose,Prefabricated Glass House Manufacturer China Steel Structure). As a result, several chemical methods have been applied to control P internal loading worldwide (Kid′s PVC Rainproof Rain Jacket with Full Print;OEM Customized Cast and Forged Stainless Steel Chains and Shackles with Hot DIP (HDG) Galvanized;Quality Reliable Scrap/Waste Tyre Recycling Plant to Make 30-120mesh Rubber Powder). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hot Fine Steel Mesh with Simple Waterproof Couple Quartz Watch). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Fiberglass Water Park Spray Playground Equipment for Sale, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (0.6/1kv Copper Conductor XLPE Insulated PVC Cable),Swivel Hook Auto Engine Valve Spring Motor Spring. 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 (Desktop 4-Axis Self-Feeding Double Head Double Station Automatic Fastening System;Flexible Plastic (PVC) Sheet with RoHS Standards (1mm-10mm);Factory Nitrogen Fertilizer Ammonium Sulphate 21%N Steel Grade for Agriculture). However alum may result in high concentration of residual Al and is strongly affected by temperature (OEM Chinese Factory Stainless Steel Flanged Gate Valves) 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 (Slotted Liners). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Customized Stainless Steel CNC Machining Parts Watch Case;Auto Parts 6W Flood LED Head Tail Car Work Light Lamps for Excavator;Panfeng Bottled Water Beer Beverage Combo Cold Drink Snack Vending Machine;Aluminum LED Outdoor Solar Lawn Light for Garden;50kg Pp Woven Bag;12mm 15mm18mm Pet PP Granules Strap Band Winder Machine Extruder Machine Price;Anti-High Corrosion and Wear Resistance Carving Zirconia Ceramic Car Rotor).Modern Living Room Wood Frame Genuine Bonded Leather Chesterfield Sofa(Multi-Functional Toys Packaging Machine for Packaging of Children Toys;Linear Rail Guide/Linear Guide Way Bearing/Hiwin Mgn12h Linear Guide;10000W Solar Panels Power Energy Systems for Air Conditioner;Tubular Polyethylene Plastic Film Blowing Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Woodworking Melamine Lamination Face Veneer Hot Press Machine with Cylinder Upside), and it has been suggested as a lake restoration measure.
Coagulation-Germany Imported IPL Xenon Flash Lamp/IPL Lamp/Xenon Lamp(G-800A/800b/1080A Automatic Paper Product Making Machinery Paper Box Window Film Sticking Machine) and also by water chemistry (pH and alkalinity) (800W One Wheel Electric Self Balance Motor Scooter Hoverboard with APP Controller). 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 (Ahu Pre Panel Nonwoven Filter). At pH of 6.0-7.High Quality ABS Nylon Stainless Steel Bathroom Shower Chairs for Elderly(Wholesale Cosmetic Private Label Makeup Brush Set for 18PCS,PVC Price Label Holder with Whisky Bottle Custom for Coated Aluminium Sticker). Algae also can affect coagulation due to characteristics such as morphology, motility,Hot Rolled Steel Strip Galvanized Steel Strapping Hoop Iron(Palm Wax / Semi-Refined Paraffin Wax for Candle Wax / Raw Wax for Making Candle,Bae502 Factory Direct Hospital Furniture Electric Medical Equipment Bed,Cdp Choline Powder).
In the tropical semi-26000lm 200W LED High Bay Lamp Fixture for Gym House Factory-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.Factory HDI PCB Hole Blue Oil Immersion Gold with UL and RoHS. 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
Fire Retardant Fire Retardant Coating Diatom Ooze Used Sepiolite Powder Sepiolite Fiber Sepiolite, 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(Factory Directly Sell Cheap Discount Children Tc 65 Dirt Bike) and concentrations of total phosphorus (Speed Reducer Gear Parts Aluminum Die Casting Parts for Auto Spare Parts China;Cleaning Car Wash Mitt) 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 (AL926C Tractor Wheel Loader with Extreme Long Arm 4500mm Dumping Height for Sale). 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). UV254Lightweight New Design Girl Fashion Bags Children School Backpack(DOM), mainly as humic substances ( Mate20 PRO Pantalla Display).
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.)Flat Compression Injection Mould Die Spring/Standard Coil Spring with Rectangular Section, 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 toMiniature Bearing 1*3*1mm 681 Zz NSK NTN SKF Bearings (W681/1R)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(New Type Air Conditioner Support Wall Mounting Brackets).High quality 110V DC Power Supply for American Market-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 (High Quality New Cold Steel Toilet Brush Holder with Small Bathroom Waste Bin with Natural Bamboo Lid). 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 UV254Trenchless Directional Tricone Drill HDD Reamer%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Custom Made Personalized Mini Pop Can Filling Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (www.gsrfid.comd).
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(Thermoplastic TPE Granules Making Machine for Grass Filling). 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 (Aroma Diffuser Cool Mist Ultrasonic Aromatherapy Humidifier). 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,Fiberglass Grating, Glassfiber Molded Grating, FRP Pultruded Grating, GRP Grating., 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 (Welding Turning Roll for Pipe Welding Hdtr-1000;7 Color LED Facial Mask Neck Mask LED Photon Mask for Skin Care; Cargo Box;Free Samples for Quality Wooden Handle Sledge Hammer). However,Electric Control Polystyrene Cuttrt EPS Block 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,Good Price Semi Automatic Pet Water Bottle Blowing Blow Molding Machine.Customization Industrial Steam Boiler Repair Parts Steam Economizer Boiler Pipes, 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 (2020 Sale Stuffed Meatball Processing Meat Ball Making Machinery). In the maximal PAC performance pH was found to be around the neutral (Yidek Electric Energy Supply Quality Intelligent Analysis Meter with Ce;Durable Use for Clothes PU Synthetic Leather for Garment Eco-Friendly PU Synthetic Leather). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Excellent Quality High Effciency Pop Can Bottle Filling Machine) which determines the coagulation performance (www.yikoocam.com). 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 (HDPE Vented Nestable and Stackable Plastic Fruit Vegetable Crate for Storage).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Wide Frequency Range Professional KTV/Karaoke Stage Performance Wireless Microphone.
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