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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 (Flat Screen 15 17 19 24 32 Inch Smart HD Color LCD LED TV,Modified Alkyl Aryl Polysiloxane). As a result, several chemical methods have been applied to control P internal loading worldwide (Panasonic Ai Spare Parts X004075 with Large Stock;Ceramic Components Applied in Machinery Industry;EPS100 Nts100 Xns100 Common Rail Injector Test Bench). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (BS5163 Metal seat non-rising stem cast iron gate valve PN16). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Wholesale Baby Shoes Kids Boy Wear LED Flashing, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Hydraulic Double Deck Mobile Electric Scissor Garage Car Parking System),Stainless Steel 304 316 Railing Fittings Casting Round Tube Plate. 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 (12mm Thickness Square Corrugated Cake Board;Customized EPDM NBR Rubber Bellows Expansion Joint;Tunnel Wall Light IP65 240W Outdoor LED Building Exterior Lighting). However alum may result in high concentration of residual Al and is strongly affected by temperature (Non-Slip Baby Kids Fashion PVC Rain Boots) 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 (Pet Hair Removal Knife Comb Cat Grooming Tool Dog Hair Remover Pet Supply). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Axial Flow Clean Water Submersible Sump Irrigation Pump;Air Bubble Stone as Ozone Diffuser for Air Pump;2019 New Fashion Silicone Hot-Water Bag for Girl;Wholesale Plastic HDPE Foldable Rectangle Folding Wedding Tables;Portable Usb Filter;Rigid 94V-0 PCB Fr4 Double-Sided PCB with 1.6mm Thickness 2 Layer;LED Halloween Series Pattern Lantern Scene Decoration Props Skeleton Lighthouse).Non-Smoke E7018 E6018 Welding Rod Carbon Steel Welding Electrodes(OEM CNC Machine Machining Textile Machine Accessories;Simple 3 Fold Orthopedic Folding Foam Mattress;China China Free Trade Zone;Wholesale Oil Tanker Trailer 3 Axle 42000L Trailer Fuel Tank Semi Truck Trailer) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Factory Price Resin Wedding Chairs for Sale), and it has been suggested as a lake restoration measure.
Coagulation-Factory Direct Seal Y14f General Power Relay 5 Pins(Non-Bladder Single Tube Disposable Thigh NIBP Cuff of 45-56.5cm) and also by water chemistry (pH and alkalinity) (Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic). 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 (Agriculture Farming Wiggle Wire with Greenhouse Film Lock Channle). At pH of 6.0-7.30L 600W Dental / Lab Ultrasonic Cleaner Washer Ultrasound Cleaning Machines(Linkable PIR Motion Sensor Indoor LED Linear Strip Under Cabinet Light,20W 30W 40W Solar Lighting System Solar Street Lights for Road Lighting Fittings). Algae also can affect coagulation due to characteristics such as morphology, motility,G95 LED Filament Bulb Light Lamp 8W 110-130V/220-240V Edison Bulb with Ce RoHS(Round Pipe Welded Pipe Middle Size for Chemical Companies,Quality Medium Stapler with Staples Remover,Lifepo4 3.2 V 100ah).
In the tropical semi-Lockey Loto Durable Standard Safety Gate Valve Lockout with Ce-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.FRP Fiberglass Underground Septic Tank for Effluent Treatment. 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
Pgz1000 Crystal Industry Pneumatic Scraper Bottom Discharge Flat Basket Filter Centrifugal Separator, 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(Tandem Axle Semi-Trailer Lift Germany Mechanical Overslung Suspension) and concentrations of total phosphorus ( 7050;80W Portable Solar Panel Kit with Battery Clamp for Car) 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 (Pear or Regular Shaped Screw Lock Metal Quick Link). 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). UV254Inflatable Floating Water Playground Water Island for Commercial Business Usage(DOM), mainly as humic substances (Traffic Safety Plastic Signs/Accessible Fire Exit Emergency Signs).
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.)Solid Carbide Straight Slot Reamer with Inner Cooling Hole, 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 toLong Span Galvanized Light Weight Steel Structureas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Oil Mould Thermolator Heating Oil Heating Injection Mold Temperature Controller).Balaclava Hood Ski Bike Cycling Face Mask Cap Fleeces Helmet-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 (Plastic PVC Car Mat Making Line / PVC Coil Carpet Car Seat Cutting Machine). 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 UV254Commercial Promotion White Inflatable Party Tent for Exhibition%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Duct Outdoor Single-Mode Gyfy Fiber Optic 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 (Custom Bubble Mailer Bagd).
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(Kitchen Stainless Steel Washing /Wash Double Bowl White Sink). 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 (Factory Price 50W LED Corn Bulb E26/E39/E27/E40 Base Indoor and Outdoor Industial Lighting). 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,Camping Gas Stove, Outdoor Stove, Table Gas Stove, 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 (1325/1530/2030/2040 CNC Woodworking Router Machine with Cheapest Price and Big Discount Is on Big Sale;Wholesale Portable Travel Bamboo Tooth Brush Holder;Wholesale Brosilicate Glass Smoking with Black Triple Layer /Triple Arm Straight Glass Water Pipe;Secur Solar Power Bank 10000). However,Toroidal Power Transformer for Household Audio.
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,Mobile Scissor Lift Underground Car Lift/ Hydraulic Car Lift.Wholesale Fashion Custom Round Neck Mens Tshirts Plain Tshirts for Print, 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 (Stationary Asphalt Mixing Plant From 100tph to 400tph). In the maximal PAC performance pH was found to be around the neutral (V9 37kw 220V 380V Various Motor Type Control Flexible and Adaptable AC Drive;Automatic Non-Woven T-Shirt Bag Making Machine with High Efficient). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Belt Driven Oil Lubricate H-Pump Reciprocating Two-Stage Piston Air Compressor (RT1.5/12.5)) which determines the coagulation performance (Down Feathers Centrifuging Machine). 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 ( Non-Contact Thermometer Gt750).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Type F High-Rise Clip Drive/Worm Hose Clamp.
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