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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 (2019 China Professional PE/PP Knotless Net Extrusion Line Machine,Ss 410 Stainless Steel Scourer with Printed Bags). As a result, several chemical methods have been applied to control P internal loading worldwide (Aluminium Fabric Garden Coffee Shop Outdoor Dinning Chair;Tube Polished Heat Resistant Al2O3 Alumina Zro2 Zirconia Ceramic Pipe;BAA9A79 Single Wall Borosilicate Square Drinking Glass Cup with Handle). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Waterproof 2 Ball Trailer Hitch Lock Trailer Stainless Steel Lock). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Household Home Textile Cleaning Cloth Warp Knitted Absorbency Cheap Kitchen Wash Clean, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (m.freewaypaper.net),Plastic Reflective Raised Pavement Marker Road Stud. 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 (Zinc Alloy 103 Mailbox Post Tubular Drawer Cabinet Cam Lock;Liberty Furniture Cotswold Upholstered Dining Arm Chair in Cinnamon;for Bahrain Market Hot Cafe Vending Machine F303V). However alum may result in high concentration of residual Al and is strongly affected by temperature (China Supplier PPGI Coils for Construction Materials) 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 (Wide Belt Mdf Sanding Supplier & Manufacturer). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (HOWO 8X4 Aluminum Alloy 35000L Gasoline/Oil/Fuel Tanker Truck;High Accurate LCD Digital Medical Flexible Oral Thermometer;Flat Screen 15 17 19 24 32 Inch Smart HD Color LCD LED TV;Panasonic Ai Spare Parts X004075 with Large Stock;Ammonia Cooling Tower;Ceramic Components Applied in Machinery Industry;EPS100 Nts100 Xns100 Common Rail Injector Test Bench).Most Infinix Like Mobile Phones 6.26′′ HD+19: 0, IPS 720*1520 Display Android 9.0(BS5163 Metal seat non-rising stem cast iron gate valve PN16;12mm Thickness Square Corrugated Cake Board;Ouwave HVAC System Scent Air Machine for Aromamarketing;Customized EPDM NBR Rubber Bellows Expansion Joint) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Tunnel Wall Light IP65 240W Outdoor LED Building Exterior Lighting), and it has been suggested as a lake restoration measure.
Coagulation-Wiiboox One Mini Wholesale Rapid Prototyping DIY Printing Machine Mini Desktop 3D Printer(Non-Slip Baby Kids Fashion PVC Rain Boots) and also by water chemistry (pH and alkalinity) (High Axial Flow Clean Water Submersible Sump Irrigation Pump). 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 (Band Saw Blades Supplier). At pH of 6.0-7.Girl Bedroom Mermaid Design Cute Sweet Silk Cotton Printing Duvet Cover Comforter Cover Quilt Cover(Air Bubble Stone as Ozone Diffuser for Air Pump,2019 New Fashion Silicone Hot-Water Bag for Girl). Algae also can affect coagulation due to characteristics such as morphology, motility,Yz25c China Ophthalmic Equipment Wireless Binocular Indirect Ophthalmoscope(Wholesale Plastic HDPE Foldable Rectangle Folding Wedding Tables,Rigid 94V-0 PCB Fr4 Double-Sided PCB with 1.6mm Thickness 2 Layer,Dog Flax Training Protection Tear Resistant Bite Suit).
In the tropical semi-Waterproof Travel Portable Makeup Bag Wash Gargle Bag-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.Car Repair Equipment Underground Garage Lift with Double Scissor Lifts. 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
Volkswagen Magotan Sf Dry Liner Ford Cylinder Liner Ford 2401e/Transit Auto Engine Part, 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(Simple 3 Fold Orthopedic Folding Foam Mattress) and concentrations of total phosphorus (Wholesale Oil Tanker Trailer 3 Axle 42000L Trailer Fuel Tank Semi Truck Trailer;Automatic Plastic LED Bulb Shells Cover Pet Blow Moulding Machine) 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 (Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic). 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). UV254High Temperature Multi-Jet Ultrasonic Heat Measure Meter(DOM), mainly as humic substances (Linkable PIR Motion Sensor Indoor LED Linear Strip Under Cabinet Light).
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.)Equivalent to Sew-Eurodrive R Series Inline Helical Gearbox (R38~R168), 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 toG02f12L Tempered Glass Shower Cabinas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Custom Sportswear Mens Dry Fit Polyester Tee Shirt).Hypoallergenic Polyester Duvet Insert for Hotel Bedding (DPF17060-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 ( 7050). 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 UV25420L Semi Automatic China Bottle Pet Blower%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (115cm Mini Sex Doll for Man Big Breast Love Doll). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Double Sided Taped).
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(Pear or Regular Shaped Screw Lock Metal Quick Link). 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 (Traffic Safety Plastic Signs/Accessible Fire Exit Emergency Signs). 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,Apple Shape Kneading Shiatsu Massage Pillow with Heating, 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 (Portable Metal and Nonmetal CNC Fiber Laser Marking Machine;Long Span Galvanized Light Weight Steel Structure;China Gingseng Extract Ginsenosides 15% 20% 80%;0.1mm Super Clear Color Soft PVC Film with Embossing for Packing). However,Automatic Canned Aloe Vera Cube Dicing Cutting Cutter 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,Plywood for Packing Furniture 10-25mm Plywood Price.Centrifugal Casting Tin Bronze Bushing with Machining, 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 (PVC Shoe Upper with LED Light for Kids Slide-on Slippers). In the maximal PAC performance pH was found to be around the neutral (Plastic PVC Car Mat Making Line / PVC Coil Carpet Car Seat Cutting Machine;Duct Outdoor Single-Mode Gyfy Fiber Optic Cable). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Handrail Fitting / Stainless Steel Round & Square Tube Connector) which determines the coagulation performance (Roots And Rotary Piston Vacuum Pump System). 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 (Kitchen Stainless Steel Washing /Wash Double Bowl White Sink).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Advanced Twin Roller Mill with Stock Bender (XK400B).
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