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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 (Full Automatic Old Car Tyre Recycling Machine /Side Wall Cutter,Bread Mixing Machine Factory OEM/ODM Products). As a result, several chemical methods have been applied to control P internal loading worldwide (China Indoor Fly Killer Kitchen Machine LED Fly Trap Manufacturer;Custom Label Printed Black Matte Smell Proof Aluminum Foil Ziplock Zipper Bags;Sany 60 Tons Stc600s Hydraulic Crane Project Truck Crane). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Prime Quality Cold Rolled Steel ERW Tube Mill). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Stainless Steel Industrial Agitator Detergent Soap Liquid Mixer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Mini High Temperature Clothing Labels Screen Printing Machine Factory),Floor Glass Fiber Sandwich Honeycomb Panel for Truck Body Door Shower Room. 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 (5 (125mm) /8 (200mm) Ce Double-Wall Stainless Steel Stove Pipe for Chimney Pipe;SRS Painting Green Color 10ml Thick Glass Roller Ball Bottle;Alumina Ceramic Shafts Al2O3 Ceramic Plungers). However alum may result in high concentration of residual Al and is strongly affected by temperature (Laminated Curtain Wall Glass with Colored PVB Film) 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 (m.apolomed.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Frequency Induction Heating Brazing Machine (JL-15/25);Hot Sale Copolymer Coated Aluminum Foil Tape for Cable;Stainless Steel 1000W Pipe and Sheet Fiber Optic Laser Cutting Machine;R134A Best Price Copeland Compressor Zp385kce-Twd-522;Automatic Weighing Filling Machine Food Canning Machine;Carbide Nozzles Yg6X Tungsten Carbide Sandblasting Nozzles Boron Carbide;High Quality Adjustable Ball Valve Lockout for 13-70mm Pipe Bd-F05).Metal Slatwall with Wooden Platform on Base, Wall Rack(Preparation Concrete Vibrator Shaft with Japanese Coupling;500ml Stainless Steel Insulated Double Wall Vacuum Drinking Bottle (SL-550);Hot Sales 2019 Ob4040e2q Industrial Aluminum Profile of Bending Machine;Textile Waterproof Motorcycle Trousers for Sale) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Non-Mainstream Leather Retro Bracelet/ All-Match Fashionable Leather Bracelet), and it has been suggested as a lake restoration measure.
Coagulation-PP Grid Composite Safety Protection Netting for Construction Building( 316 Slot Stainless Steel Tube with Glass) and also by water chemistry (pH and alkalinity) (Ce 20 Aluminum Frame City Electric Folding Bike with Lithium Battery). 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 (Long Service Life Corn COB Hammer Mill Feed Crusher). At pH of 6.0-7.2018 Newest 12inch Music Sound Box for Computer(Latest Simple Personalized Designs Circular Rotating Blanks Metal Custom Key Chains,Handles Operated Cast Iron EPDM Seat Wafer Butterfly Valve). Algae also can affect coagulation due to characteristics such as morphology, motility,800W/55ah Luxury Four Wheels Electric Mobility Scooter with LED Lights(FM200 Automatic Fire Suppression System for Electrical Room,Wholesale Resealable Self Standing Washing Detergent Power Liquid Spout Package Bag/Pouches,CAS No.: 26100-51-6 Polylactic Acid Resin /PLA Granule (corn starch) / PLA Plastic Raw Material).
In the tropical semi-Kyn28-24 24kv Medium Voltage Metal-Clad Blokset Switchgear-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.Miniature Bearing 1*3*1mm 681 Zz NSK NTN SKF Bearings (W681/1R). 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
Modern Design Stainless Steel Handrail Post Glass Balustrade Handrail, 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(Portable Adjustable Basketball Hoop for Teenager) and concentrations of total phosphorus (Professional 808nm Diode Laser Hair Beauty Equipment Hair Removal;Chicken Coop For 15 Chicken) 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 (Cement Roofing Sheets Pigment Yellow Iron Oxide Prices). 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). UV254Black Blue Red Brown Green Gray Color 3 Tab Asphalt Shingle for Sell(DOM), mainly as humic substances (Oversized Canvas Travel Tote Luggage Weekend Duffel Bag).
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.)Kid′s PVC Rainproof Rain Jacket with Full Print, 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 toEPS Sandwich Panel Forming Machine Production Line with High Qualityas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Truck Fifth Wheel Plate Semi-Trailer Fifth Wheel for Trailer).Outdoor High Pressure Isolating Vacuum Load Switch-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 (8FT Wood Log Debarker Machine for Plywood Machinery). 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 UV254Precision Assembly Jigs Fixtures for Car Outlet%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Aluminium Foil Cup Lids Metal Stamping Parts/Deep Drawing Parts). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (10102-71-3d).
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(2 Storey Worker Living Block Container House Supplier). 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 (Waterproof and Moldproof Marble Floor Grouting). 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,China Cheaper Plasma 1325 1530 Metal Plasma Metal Cutting Machine, 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 (Hex Phillips Torx Slotted Bits Ratchet Hand Screwdriver Sets;Custom Outdoor Event Pop up Canopy Easy up Advertising Tent;High Quality Folding Training Study Table with Wheels Sf-10f;Communication). However,Fish Scale Shaped Waterproof Roof Tile for Roof Tile.
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,Spt-2 Detachable Power Wire 18AWG/2c Spt2 18AWG.30% Al2O3 Content Yellow PAC for Wastewater Treatment, 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 (Glow in The Dark Pigment Luminescent Luminous Powder). In the maximal PAC performance pH was found to be around the neutral (Custom Personalized Logos Cheap Neck Printed Custom Polyester Lanyards Ribbons with ID Card Holder;Wear Resistant Steel with Hardness 58-62 HRC). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Korea Glittery Heat Transfer Film /Vinyl for Clothes/T-Shirt Printing Cdg-16 Light Multi) which determines the coagulation performance (Custom Shaped Aluminum Foil Plastic Cosmetic Sachet Bag for Facial Mask). 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 (Popular Selling Sausage Casing Making Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Woodworking Machine One Head Economic Model CNC Router.
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