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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 (Slip on Blind Weld Neck Stainless Steel Flange Including Welding Neck Flange,coconut hide for crested gecko). As a result, several chemical methods have been applied to control P internal loading worldwide (Large Lifting Force Detachable Hydraulic Drilling Rig Machinery for Sale;Good Quality White and Brown Paper Soup Containers;Sf606 Serve Motor Automatic Wood Cut off Saw Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Saint Glory-Washable White Color Down Alternative Comforter for Hotel (Home), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (C45 Concrete Nails),Waterborne Epoxy Resin for Waterborne Epoxy Coatings. 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 (Commercial Lighting Hotel Bar LED Track Lights;One Step Medical Diagnostic Rapid Dengue Ns1 Antigen Test Kits (Colloidal Gold) Dengue Test Kit;Stainless Steel Perforated Metal Grain Sieve). However alum may result in high concentration of residual Al and is strongly affected by temperature (Women′s Mesh Contrast Pleat Fashion Black Tank Top) 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 (Shenzhen Plastic Products Manufacturers Injection Mould Used Moulding). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (130 T/H Water-Cooling Vibrating Grate Cotton Fired Boiler for Power Plant;24-410 White PP Plastic Land Seal Pivot Spout Caps for HDPE Cylinder Bottles;Kayal Best Quality 4 Pins 5 Pins Auto Relay 12V; Auto Seal Stainless Steel Travel Mug Cup (SH-SC36);Ceramic Blade Hair Trimmer;Port Bulk Cargo Tire Mounted Truck Loading Dust Control Eco-Hopper;VRLA Deep Cycle Storage Battery 12V 100ah (QW-BV100A)).High Quality Galvanized Welded Wire Mesh Panel Roll(Customized Lift Gas Support Spring with Metal Eyelet End Fitting;Dashboard Sz958000730 for Shacman Delong F3000 / M3000;Complex Shape Stamping Parts;Kanzo HSS Circular Saw Blades for Cutting Brass and Copper Billets) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Stainless Steel Sanitary Control Butterfly Valve Electric Actuator Ball Valve), and it has been suggested as a lake restoration measure.
Coagulation-RGB Indoor P4 Full Color Creative Flexible LED Display with Nationstar Lamp(30g 50g Plastic PP Empty White Cosmetic Cream Jar) and also by water chemistry (pH and alkalinity) (Fiberglass Grating). 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 (LCL Consolidation Shipping Freight From Guangzhou to Cincinnati). At pH of 6.0-7.3/4inch Flexible Aviation Rubber Fuel Hose Making for Gas Station(Decorative Line Color Metal Trim Strip L Shape Stainless Steel Tile Trim for Hotel,2019 New Product 12mm Mini Short Metal Push Button Switch). Algae also can affect coagulation due to characteristics such as morphology, motility,Hot Sales Vinyl Insulation PVC Electrical Tape Manufacture RoHS2.0(Black Blue Red Brown Green Gray Color 3 Tab Asphalt Shingle for Sell,Dental Alloy Cobalt Chromium porcelain Fused to Metal,Flat Tact Membrane Switch).
In the tropical semi-Luxury Goose Duck Down Feather Filling Pillow for Hotel Home-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.Silicone Rubber Pin Insulator/Polymer Composite Insulator (10kv-33kv). 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
Stainless Steel Axle Shaft, Input Splined Drive Shaft, 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(Higher Quality Easy Installation Luxury Vinyl Tile Spc Flooring Plank) and concentrations of total phosphorus (Roll Forged Steel Sheaves for Crane Sheave Block;Stainless steel cable Ties-L Type Ball-Lock Polyester Coated Ties) 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 (Shacman F3000 6X4 6000 Gallon Oil Tanker 20000liters Fuel Tank Truck). 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). UV254220-240V 110-130V LED Wall Lamp Die-Casting Aluminum LED Garden Light(DOM), mainly as humic substances (Ce Approved Cheap Medical Disposable Electrical Infusion Pump).
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.)Australian Standard Thermal Break Residential Aluminium Wooden Glass Sliding Window, 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 toMorgan Carbon Brush/Carbon Brush for Forklift/Denso Window Motor Brushas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Rubber and Metal Bonded Ring/Stainless Steel / Metal/ Brass Bonded Washer O Rings).Metallzied Polyester Film 9um MPET Film for Capacitor Use-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 (Car Accessories Wholesale 60 Cm Semi-Metal Car Wiper Blade Used for Toyota 85212-42110). 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 UV254Nail Sterilizer Disinfection Box Salon Nail Tools Disinfector Sanitizer Box%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Fashion Classic Korea Designs Denim Pinafore Teen Dress for Kid). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Oil Proof and Impact Resistant Hand Protection Safety Glovesd).
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(Compostable White Take Away Disposable Paper Lunch Box). 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 (Price of High Density Polyethylene Crane Track Mats HDPE Temporary Road Mats). 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,Filterb HEPA Filter for Air Purifier Germguardian Flt4825 AC4825 AC4850PT, AC4900ca, 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 (Gfbc1560-6inch Birthday Candles 60 Seconds Birthday Cake Smokeless Safe Cold Fireworks;Flexible Cloth Backdrop P18 3X6m LED Video Curtain;1oz Square Glass Storage Mason Jar with Cork Lid;Plastic Key Tags). However,Baby Teething Toy Wooden Bunny Round Ring Teether.
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,Small Cable Reel 5m Extension Cord for Home Appliance Humidifier.2018 Small Machine Room Gearless Traction Xide Passenger Elevator, 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 (2016 500W Razor Crazy Electric Drift Trike for Adult). In the maximal PAC performance pH was found to be around the neutral (Low Cost Commercial Plastic Film Greenhouse for Sale;Diamond Silver Ring Silver Plated Zircon Butterfly Shape Women Ring). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose) which determines the coagulation performance (Defection Biological Safety Cabinet Suppliers for Sale). 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 (11mm Neck Crimp Cap Vials with Patch).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Foton/Forland 4X2 Mobile Snack/BBQ/Coffee/Hot Food Truck.
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