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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 (Multiple Selection Foldable Fashion Waterproof Travel Toiletry Cosmetic Makeup Bag,Refillable Waterproof Haircare Travel Bottle Kit for Hotel with Bamboo Soap Pump). As a result, several chemical methods have been applied to control P internal loading worldwide (Top Quality Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant;Eco Brava Small Mud Interlock Brick Press Machine;7 Inch Diamond Double Row Abrasive Grinding Wheels for Stone Polishing). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Textile Machine Parts Multiple Pattern Box). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,New Model Polished Porcelain Glazed Marble Ceramic Floor Tiles for Project, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Copper Continuous Casting Machine),Bottles Juice Glass Bottles Liquid Filling Line Beverage Processing Machinery. 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 (Elevator Door Phone Industrial Telephone Knzd-15 for Clean Room with Double Loudspeaker;Accept Customization Perfume Direct with Good Price;AAC Autoclaved Aerated Concrete Brick Making Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Cooking Oil Filters South Africa Cooking Oil Cleaner and Filter) 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 (Navy Blue Mens Causal Cargo Pants with 90%Nylon 10%Spandex Fabric). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Geekvape Aegis Squonk Tc Kit 100W Wholesale Price E Cigarette;FM Mini Portable Voice Music Amplifier Wired Microphone for Teachers with HiFi Sound;Kindergarten Themes Children Furniture Sets Classroom Adjustable Baby Chair;2400 Dpi Resolution Offline CTP Offset Printer;High Quality Custom Printed Polyester Shower Curtains;Trailer Part Coupling;Small MOQ Food Grade Glass Bottle Wine Cork Stopper).Stainless Steel Black Matt Kitchen Faucet(High Quality Precision Plastic Mold/Mould Insert;Alternator for Toyota 91;Mifare 1k Inlay;Guard Rail Roll Forming Machine 2.0-4.0mm Thickness) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (China Genuine Leather White Color Safety Shoes), and it has been suggested as a lake restoration measure.
Coagulation-Ceramic Components Applied in Machinery Industry(HS20-600 Shipping Lifting Device Customized Hydraulic Station) and also by water chemistry (pH and alkalinity) (China Supplier Customized Polish Storage Wall Mounted Wine Rack). 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 (Unisex 3D Printed Pullover Fleece Hooded Sweatshirt Drawstring Hoodies for Mens Womens Kids). At pH of 6.0-7.Rock Wool Color Steel Sandwich Panels for The Construction of Cleanroom(Manufacturer of Titanium/Alloy Titanium Bolt and Nut for Bicycle Use,Zp9 Punches and Dies Rotary Tablet Press for USA Market). Algae also can affect coagulation due to characteristics such as morphology, motility,Wall Mounted Bathroom Tissue Holder Toilet Paper Towel Roll Holder(Professional Manufacture C Frame Power Oprated 10 Ton Yq41 Hydraulic Punch Press,Ce Marked Nylon Disposable Cleaning Brush for Endoscope Channel,PP Wire Wheel Cleaning Brushes and Industrial Round Floor Tile Polishing Brush).
In the tropical semi-Ride on Concrete Power Trowel Machine with Suitable Seat-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.Concrete Grinding Plate for Abrasive Machines of Abrasive Disc. 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
Duplex Parallel Connection Bag Filter for Filtering Drinking Mineral Water, 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(Commercial Promotion White Inflatable Party Tent for Exhibition) and concentrations of total phosphorus (Mobile Fast Food Vending Hot Dog Concession Trailer/Cart Pizza Truck/Mobile Food Car;Spray Guns Cleaning) 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 (Frontlit PVC Flex Banner for Outdoor Advertising). 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). UV254China New Design TPU/PVC Layflat Flexible 6 Light Duty Suction Hose(DOM), mainly as humic substances (Cc+ Hot Sale Atc Spindle with Gmn Bearing Air Cooling Spindle Same as Italy Hsd).
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.)2018 Chinese Single Person Best Plastic Fishing Kayak Sit on Top, 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 toODM OEM Custom Stainless Steel Sheet Metal Fabrication Service Product Sheet Metal Worksas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Custom Juggling 5cm Play Ball for Promotional Gift).Laminated Glass Auto Clave with TPC/PLC System (SN-BGF3060)-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 (China Supply High Quality MIFARE® DESFire® EV1 2K/4K/8K RFID White PVC Card). 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 UV254Modern Design Oval LED Lighted Beveled Edge Wall Fogless Bathroom Mirror%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (TUV Standard China Jump Park Free Jumping Bounce Bed Trampoline Park for Kids). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Extra Large Glow in The Dark Full Moon Kids Fun Wall Decal Sticker 3Dd).
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( Portable Home Dehumidifier for Whole 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 (LED Display Fixed Co Gas Monitor Toxic Gases Analyzing). 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,7 Inch Wired Color Villa Video Door Phone with Coms Camera V7c-P1 Intercom System, 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 (Disposable Rotatable Endoscopic Grasping Net Loop;Composite Suspension Transmission Insulator String with Electrical Power Fitting;SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker;50tons-60tons 3 Axles 13 Meters Low Flatbed Semitrailer). However,Monofilament Fishing Tackle Green Nylon Fish Net.
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,IP65 Waterproof Metal Distribution Box and Power Metal Box.Original Sinotruk HOWO Truck Spare Parts Trailer Control Valve Wg9000360525, 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 (Aluminum DJ Truss for Exhibition Lighting Truss). In the maximal PAC performance pH was found to be around the neutral (Biodegradable PLA Film for Food /Fruit Packaging;Automatic Paver Block Making Machine for Sale). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (12 Hooks Wood Coffee Mug Holder Rack for Kitchen Storage) which determines the coagulation performance (Auto Plastic Part Hardware Plastic Injection Mold). 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 (Outdoor Body-Building Sitting Device for Improving Stability of Lower Limbs).
Metallic Paint Solid Aluminum Cladding Panels for Roof Covering/ Ceiling, charge and density, factors that influence directly in flock sedimentation.New Designer PU Fashion Ladies Backpacks Handbags for Brand Holder and Wholesale(Commercial Overhead Automatic Aluminum Insulated Roller Shutter Door for Garage or Workshop; Solar Water Pump for Garden Irrigation (SC Series)). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Smart Label RFID UHF Sticker with Special Offer for Asset Tracking). Extracellular and surface-Cal117 (TB117) Flame Retardant Fire Barrier Batting Felt(Patent Curtain Coating Wood Grain PU Leather Mirror Surface,Painted Black Grade U3 Studless Boat Anchor Chain for Sale). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (2019 Hot Sale Solar Light String Tree Park Decoration Light), which can be one important cause of the increase in coagulant demand in algae-rich waters (New Style Customized Ce Approved Adjustable Inline Skate (SS-179A-BW)).Sri Lanka Metal Detector Handheld Metal Detector Explosive Detector(Throttle Body Valve Plastic Heater Inlet Pipe 55559352 for GM Chevrolet Cruze), particularly humic susbtances. Humic substances are highly negatively charged (m.bolionfpc.com), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Professional Produce Dmp-430A Vacuum Tray Sealer). Maximal UV254removal was observed to be found around pH 6.0 (Digital Universal High Power Ku Band Single LNB Price). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (High Quality Centrifugal Industrial Push-Pull Ventilation Husbandary Exhaust Fan).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Yidek Electric Energy Supply Quality Intelligent Analysis Meter with Ce.
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