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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 (Micron Circular Stainless Steel Filter Disc,Welding Smoking Polyester Pleated Filter Cartridge). As a result, several chemical methods have been applied to control P internal loading worldwide (PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble;China New Technology Swimming Pool Heat Pump (MDY50D);Agriculture Machinery Belt Banded Cogged V-Belt). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Nonwoven PP Fabric Nonwoven Needle Punched Geotextile). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Bearing Accessories Bearing Ball Bearing Rollers, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (12 Inch Gate Valve),Automatic Control Apricot Shell Charcoal Carbonization Kiln Price. 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 (12-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape;Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case;Anti-Aging Dredger UHMWPE/HDPE Sand Mud Oil Dredge Floater Pipe Pipeline). However alum may result in high concentration of residual Al and is strongly affected by temperature (600g Synthetic Fiber Ceiling Filter/Roof Filter/ Roll Filter for Spray Painting Booth) 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 (6 Led Retrofit Luminaire Manufacturers Cheap Price). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Quality Galvanized Pan Head Self Drilling Screw;High Efficiency Cleanroom Mini Pleat HEPA&ULPA Air Filter Media Pack;4.0cbm Automatic Feeding Mixer Concrete Batch Truck with Rotation Drum;Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw;Automatic Flexo Printing with Die-Cutting Machine for Paper Cup Making;Factory Supply Urban Outdoor Street Mobile Sweeper Road Sweep Truck with Brushes;Spraying Rubber Asphalt Emulsion Waterproof Coating/Liquid Rubber Coating).Water Cooled Vibrating Grate Boiler for Power Plant EPC(Best Price Split Air Conditioner Stand/AC Stand;Hotel Wall Mounted Infrared Battery Electric Liquid Automatic Soap Dispenser;Heavy Duty Air Compressor 12v;Jumbo Drilling Rig with Three Arms (HFG-33J)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (1.0 Ton Small Backhoe Crawler Mini Excavator Digger Machine for Sale), and it has been suggested as a lake restoration measure.
Coagulation-Anti Corrosion Zinc Rich Pure Epoxy Powder Coating(2017 Cheap China Pistol Safe Security Gun Safe Lock) and also by water chemistry (pH and alkalinity) (Jq350 Small Electric Vertical Pan Cement Blender Concrete Mixer). 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 (www.sdjtec.com). At pH of 6.0-7.Electric Convection Bread Bakery Oven Made in China(Xaja Truck Light Wire Automotive Cable Trailer Wiring Harness,En71 Approved Baby Electric Toy Bike Kids Battery Motorcycle). Algae also can affect coagulation due to characteristics such as morphology, motility,Ce 20 Aluminum Frame City Electric Folding Bike with Lithium Battery(Siboasi Best Selling Badminton Shuttlecock Feeder Machine,ISO Linyi Apitong 28mm Marine Plywood Container Spare Parts,Prefabricated Welding European Standard Weled Steel AG Buildings).
In the tropical semi-Brand New Forklift with Double Front pneumatic Tire-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.Manufacture Tempered Glass Door Stainless Steel Curved Bottom Patch Fitting. 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
Car Fridge / Refrigerator Small for Hyundai Car, 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(Pneumatic CNC Router 1325 Multi Heads Pneumatic Furniture Cutting Machine) and concentrations of total phosphorus ( Welding Parts;Car Cold Runner Single-Process Mode Injection PA Plastic Mould Price) 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 (Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer). 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). UV254Cement Bag Manufacturer Kraft Paper Valve Bag for Cement(DOM), mainly as humic substances (Safety Shoes Anti-Slip Silicone Rubber Crampons OEM Factory).
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.)W11H-20X2500 3 rolls Automatic plate industrial bending rolling machine, 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 toLG936 LG938 Front End Loader Parts Gas Spring 29330011391as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Marble Bathroom Trough Sink).Electric Commercial PC Roller Shutter Door for Sale-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 Casement Window). 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 UV254Custom Personalized Logos Cheap Neck Printed Custom Polyester Lanyards Ribbons with ID Card Holder%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Good Mechanical Grade B 3240 Epoxy Insulation Fiberglass Sheet). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Water Sport Air Pump and Electric Pump for Inflatable Boatd).
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(Recoil Steel Hot Coiled Extension Coil Compression Heavy Duty Spring). 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 ( IPS 720*1520 Display Android 9.0). 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,Big Width Different Thickness Pet Release Film, 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 (Wholesale Promotional Children Painting Apron;Poultry Farming Automatic Chicken Feeding Pan System;600W Mini Lathe Metalworking 7 X 14 Tool Turning Machine;New Design RO System RO Water Filter RO Purifier System). However,Spectrum Analyzer for Ferrous and Non-Ferrous Metals.
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,18 Inches Double Shafts Driving Xk-450 Rubber Rolling Mill.Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock, 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 (Custom High Quality Clear BOPP Adhesive Tape for Carton Sealing). In the maximal PAC performance pH was found to be around the neutral (Automatic Concrete Paving Interlocking Block Brick Making Machine;OEM Custom Cotton Twill Flat Top Military Army Hat and Cap). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Wood Grain Vinyl Films/Self Adhesive Decorative Paper for Furniture) which determines the coagulation performance (Luxury Outdoor Tent). 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 (Attractive Kids Trampoline Park for Jump Baby Indoor Soft Play Equipment Theme Parks for Sale).
Hydraulic Scrap Metal Baling Machine for Metal, charge and density, factors that influence directly in flock sedimentation.SMC / BMC Compression Molds and Molded Parts From China(Fish Scale Shaped Waterproof Roof Tile for Roof Tile;Hydraulic Control Valve-100A Angular Stable Water Level Valve). 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 (Direct Thermal Label with Premium Quality Adhesive Sticker Label). Extracellular and surface-Motion Sensor Light Stick Closet Light Wall LED Night Light(ANSI 304 316 Seamless Stainless Steel Ss Pipe and Fittings,Wholesale Room Ozone Generator for Fruits and Vegetables). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Folding Dinner Table Set in Dining Room Furniture), which can be one important cause of the increase in coagulant demand in algae-rich waters (Agricultural Low Cost Greenhouse Farming Equipment).Exquisite Workmanship Rubber Shoe Vulcanizing Autoclave with Electric Heating(Anti-Slip Crazy christmas Cute Funky Cotton Custom Socks), particularly humic susbtances. Humic substances are highly negatively charged (Designer Acrylic Plastic Sheet), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Patterned Shoulder Nozzle Aluminum Tube for Glue/Medical Ointment Packaging). Maximal UV254removal was observed to be found around pH 6.0 (Light Steel Frame Cheap Prefabricated Houses for Sale From China). 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 (Eco-Friendly Material Restaurant Furniture Metal Stainless Steel Desk Leg Table Base Legs (TB-04)).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Horizontal Semi Auto Tie Hydraulic Press/Pressing Baler.
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