Improvement of Dewatering Characteristics of Aerobically Digested Sludges

1993 ◽  
Vol 28 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Hasan Z. Sarikaya ◽  
Salah Al-Marshoud
Keyword(s):  
Linear Relationship ◽  
Mixing Time ◽  
Optimal Dose ◽  
Optimum Dose ◽  
Cationic Polymers ◽  
Operational Parameters ◽  
Capillary Suction ◽  
Solids Concentration ◽  
Slow Mixing ◽  
Aerobically Digested

The aim of this study was to evaluate the influence of both sludge characteristics and operational parameters on polymer selection and optimal dose requirements to improve the dewatering characteristics of aerobically digested sludges of a contact stabilization activated sludge plant in Jeddah, Saudi Arabia. In order to determine the dewatering characteristics of the sludge samples, capillary suction time (CST) and specific resistance to filtration (SRF) were measured. Cationic conditioning polymers were found more effective than the anionic types. The optimum polymer dose was equal to 4.2 kg of polymer/ton of dry matter for three of the cationic polymers used in this study namely Zeetag 57, Superfloc C420, and Zeetag 92. The optimum dose requirements are increased substantially with increasing pH values. A linear relationship was found between the optimal polymer dose in mg/l and the sludge solids concentration. The optimum total mixing time was found to be 2 min: 30 sec of rapid mixing at 100 rpm and 90 sec of slow mixing at 40 rpm. The sludge temperature variations were found to have a slight effect on polymer dose requirements. A linear relationship was obtained between the CST and SRF with a correlation coefficient of 0.99.

Mixed Culture Microalgae Removal for Water Quality Improvement Using Chitosan

2020 ◽  
Author(s):  
Gulab Singh ◽  
S. K. Patidar
Keyword(s):  
Water Quality ◽  
Algal Biomass ◽  
Culture Medium ◽  
Mixing Time ◽  
Operational Parameters ◽  
Efficient Removal ◽  
Mixing Rate ◽  
Beneficial Uses ◽  
Improve Water Quality ◽  
Slow Mixing

The presence of microalgae affects water quality and beneficial uses of surface freshwaters. Chitosan with proven potential for harvesting specific microalgae species from their culture medium for producing biofuels and bioproducts appears promising for efficient removal of mixed microalgae species from surface freshwaters also. The main thrust of the present study was on removal of mixed microalgae species using chitosan as a coagulant to help improve water quality. Important operational parameters were optimized for economical microalgae removal. The microalgae cells, chlorophyll-a, TN and TP removal efficiency were 82.06, 89.90, 69.32 and 44.01%, respectively at an optimum chitosan dose of 10 mg/L, pH 8, slow mixing time 7 min, slow mixing rate 30 rpm and settling time of 15 min. The results have shown that chitosan coagulation efficiently removed the mixed microalgae species from surface freshwater with significant improvement in water quality and recovery of algal biomass for other beneficial applications.

scholarly journals Determination of the optimal dose and date of application of mineral manure on sesame (sesamum indicum L.) in Burkina Faso

2021 ◽  
Vol 14 (9) ◽  
pp. 2992-3000
Author(s):  
Amos Miningou ◽  
Vanessa Golane ◽  
Appolinaire Sy Traore ◽  
Hyacinthe Kambire
Keyword(s):  
Burkina Faso ◽  
Cost Effective ◽  
Optimal Dose ◽  
Fertilizer Application ◽  
Sesamum Indicum ◽  
Optimum Dose ◽  
Mineral Fertilizers ◽  
Morphological Development ◽  
Split Plot

The decrease in soil fertility is the main cause of low crops yields in Burkina Faso. It is therefore necessary to make a supply of fertilizers to increase yields. This is the reason why during the 2015 rainy season from July to October, a study was conducted on sesame fertilization in Souri located in the Province du Mouhoun. The goal of our study is to fertilize plants with increasing doses of mineral fertilizers at different application dates on sesame. The objective is to determine the optimum dose and date of fertilizer application to increase the yields. For this purpose four NPK (14-23-14) fertilizer treatments have been experimented with following doses NPK0 (0kg.ha-1), NPK50 (50 kg.ha-1) NPK100 (100kg.ha-1) NPK150 (150 kg.ha-1) with three application dates (sowing, 15 DAS, 30 DAS) in Fisher’s completely randomized blocks with four replications in split-plot. The results showed that NPK doses had an effect on sesame throughout morphological development (height, number of ramifications, number of capsules) and yield performance. Yields have increased according to the doses applied in the following order: NPK0 (226 kg.ha-1) < NPK50 (348 kg.ha-1) <NPK100 (550 kg.ha-1) <NPK150 (593 kg.ha-1). Through economic calculations, the NPK100 dose with 550 kg.ha-1 yield can be chosen as the most cost-effective dose for producers. The application dates of NPK had various effects on sesame that emerged on the height and grain yield. The plants had the best performance on the date of application of the 15 DAS (475 kg.ha-1) followed by the application at planting time (450 kg.ha-1) and at the end the application on 30 DAS (375 kg.ha-1). Interaction between the doses and the dates of application of fertilizer is significant and should be considered in sesame. La baisse de la fertilité des sols est une cause des faibles rendements au Burkina Faso. Ainsi, il faudra faire de bons apports d’engrais pour augmenter les rendements. Dans ce cadre, une étude a été conduite de juillet à octobre 2015 à Souri dans la Province du Mouhoun. Il s’est agi d’apporter des doses croissantes de fumure minérale à différentes dates d’application sur le sésame. L’objectif est de déterminer la dose et la date d’application optimales de la fumure minérale. A cet effet quatre traitements de doses d’engrais NPK (14-23-14) : NPK0 (0 kg.ha-1), NPK50 (50 kg.ha-1), NPK100 (100kg.ha-1), NPK150 (150 kg.ha-1) ont été appliqués selon trois dates d’application (au semis, le 15ème JAS, le 30ème JAS) dans un dispositif expérimental en blocs de Fisher à 4 répétitions avec un arrangement en split-plot. Les résultats obtenus ont montré que les doses NPK ont un effet positif sur le sésame à travers son développement morphologique (sa hauteur, ses ramifications, ses capsules) et son rendement. Les rendements obtenus ont permis de classer les doses selon cet ordre croissant : NPK0 (266 kg.ha-1) <NPK50 (348 kg.ha-1) <NPK100 (550 kg.ha-1) <NPK150 (593kg.ha-1). L’évaluation économique effectuée sur la base du ratio valeur sur coût (RVC) a permis de retenir la dose NPK100 comme étant la plus rentable pour les producteurs. Les dates d’applications NPK sur le sésame ont également des effets visibles sur la hauteur et le rendement en grain. Le meilleur rendement est obtenu avec l’application du NPK 15 JAS (475 kg.ha-1) suivi de l’application au semis (450 kg.ha-1) et enfin de celle effectuée au 30ème JAS (375 kg.ha-1). L’interaction doses et dates d’application d’engrais NPK doit être considérée chez le sésame.

scholarly journals Selection the optimal dose of application associated vaccine against rota-, coronavirus infection and colibacillosis in calves

2021 ◽  
Author(s):  
Y. P. Yaromchyk ◽  
P. А. Krasochko ◽  
P. P. Krasochko ◽  
V.M. Eremets ◽  
T.A. Skotnikova
Keyword(s):  
Blood Serum ◽  
Research Work ◽  
Optimal Dose ◽  
Farm Animals ◽  
Optimum Dose ◽  
Bacterial Cells ◽  
Serological Studies ◽  
Coronavirus Infection ◽  
Pathological Material ◽  
And Control

The main rules for choosing the means of specific prophylactic against colibacillosis (escherichiosis) in cattle is the need to match the antigenic spectrum of the vaccine strains with epizootic strains isolated by diagnostic veteri-nary institutions from pathological material taken from dead calves. Only in this case one should expect high results of the preventive efficacy of the applied vac-cines. The design of vaccines based on pathogenicity factors of bacterias is the most promising direction in the development of new bioproducts of specific pre-vention of infectious diseases of farm animals. Researchs in the areas to choice the optimal doses and ratios of monocompo-nents, determining the optimal immunizing dose, and choosing a adjuvant is an im-portant part of research work on the creation of vaccines. We completed work to establish the optimal dose when using the associated vaccine against rota-, coronavirus infection and colibacillosis of cattle by vaccinat-ing cows in different doses of the test vaccine. Subsequently, serological studies of the blood of animals were carried out, according to the results of which the indica-tors of the best immune response were determined by comparing the established levels of biosynthesis of specific antibodies from animals of the experimental and control groups. A number of indicators of possible reactogenicity of the tested vac-cine were also studied. When conducting studies of blood serum of cows, the indi-rect hemagglutination reaction and agglutination reaction were performed. Serolog-ical blood tests carried out were accompanied by the necessary controls to ensure the reliability of the results. According to the results of studies of blood serum of cows in the experimental groups, immunization of cows with an associated vaccine against rota-, coronavirus infection and colibacillosis of cattle in different volumes led to a significant level of antiviral and antibacterial antibodies. The optimum dose for virus antigens with infectious titres from 7,0 lg and 5,5-TCI50/sm3 for vaccinated cows forms 1,5 sm3 for each viral monocomponents. The optimum dose for each vaccine strains E.coli F4, F5, Аtt25, F41 and 987P forms from 1,5-2,5 milliard bacterial cells for each bacterial monocomponents.

scholarly journals Kajian Peningkatan Peran Azolla Sebagai Pupuk Organik Kaya Nitrogen pada Padi Sawah

2017 ◽  
Vol 14 (2) ◽  
Author(s):  
Iwan Gunawan
Keyword(s):  
Block Design ◽  
Organic Fertilizer ◽  
Growth Yield ◽  
Maximum Growth ◽  
Optimal Dose ◽  
Rice Paddy ◽  
Organic Fertilizers ◽  
Growth And Yield ◽  
Optimum Dose ◽  
Randomized Block Design

The study aims to get an optimum dose of Azolla organic fertilizer that provides maximum growth and yield of rice crops. The experiments are arranged in complettely randomized block design with 5 treatments and 4 replications. The treatments tested were fresh Azolla biomass dose embedded in the ground to accompany the provision of Azolla that left to grow on the surface of the water of the rice fields. Treatments dose of fresh Azolla biomass awere M0 = control (without organic fertilizer Azolla); M1 = 100 g.pot-1 ; M2 = 200 g. pot-1; M3 = 300 g. pot-1 ; and M4 = 400 g. pot-1. The experimental results show that: (1) organic fertilizer Azolla improve the growth and yield of rice paddy fields, and (2) Results of maximum 56.35 grams of dry grain per plant with an optimal dose of organic fertilizer as much as 48.102 ton.ha -1. Keywords: Organic fertilizers, Fresh Azolla, growth, yield, rice paddy.

scholarly journals Infantil Hemangioma and Optimum Dose of Propranolol Treatment: A Retrospective Tertiary-Center Study

2021 ◽  
Author(s):  
Hatice Mine Cakmak ◽  
Omer Kartal
Keyword(s):  
Adverse Event ◽  
Optimal Dose ◽  
Infantile Hemangioma ◽  
Optimum Dose ◽  
Final Dose ◽  
Tertiary Center ◽  
Propranolol Group ◽  
Propranolol Treatment ◽  
Center Study

Abstract Background/Objectives: Propranolol is the mainstay treatment of infantile hemangioma, and the optimal dose is unclear. Few studies are comparing the efficacy of propranolol dose of 2 vs.3 mg/kg/day. We compared the efficacy between these two doses and propranolol groups with no treatment group. Methods: One hundred eight patients with infantile hemangioma (15 days-27 months of age) were examined. The patients with high-risk features and/or a score of >6 points are given propranolol with a final dose of 2 or 3 mg/kg/day according to tolerance for 6-12 months. The resolutions rates for propranolol vs. placebo and propranolol 2 mg/kg/day vs. 3 mg/kg/day are compared. Results: The demographic and clinical features of the groups ( the non-treatment, propranolol 2 mg/kg/day group, propranolol 3 mg/kg/day group) are similar. Propranolol is significantly efficent in infantil hemangioma treatment (p<0.001). The resolution rates are not statistically different between 2 mg/kg/day propranolol group vs 3 mg/kg/day propranolol group at the sixth (68,59 ± 28,95 vs 73,44 ± 32,54)(p=0,673) and twelfth month (p=0,673) (89,08 ± 46,58 vs 91,13 ± 37,46 respectively )of follow up. A milld (n=3)(4%) adverse event was reported with no need for cessation.Conclusions: Propranolol is a safe drug for treating infantile hemangioma with an ideal dose of 2 mg/kg/day rather than 3 mg/kg/day.

Extracellular polymers of ozonized waste activated sludge

2001 ◽  
Vol 44 (10) ◽  
pp. 137-142 ◽  
Author(s):  
J.C. Liu ◽  
C.H. Lee ◽  
J.Y. Lai ◽  
K.C. Wang ◽  
Y.C. Hsu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Activated Sludge ◽  
Weight Distribution ◽  
Specific Resistance ◽  
Optimal Dose ◽  
Cationic Polyelectrolyte ◽  
Waste Activated Sludge ◽  
Extracellular Polymers ◽  
Capillary Suction ◽  
Ozone Dose

Effect of ozonation on characteristics of waste activated sludge was investigated in the current study. Concentrations of cell-bound extracellular polymers (washed ECPs) did not change much upon ozonation, whereas the sum of cell-bound and soluble extracellular polymers (unwashed ECPs) increased with increasing ozone dose. Washed ECPs in original sludge as divided by molecular weight distribution was 39% &lt; 1,000 Da (low MW), 30% from 1,000 to 10,000 Da (medium MW), and 31% &gt; 10,000 Da (high MW). It was observed that the low-MW fraction decreased, and the high-MW fraction increased in ozonized sludge. The unwashed ECPs were characterized as 44% in low MW, 30% in medium MW, and 26% in high MW. Both low-MW and medium-MW fractions of unwashed ECPs decreased while high-MW fraction increased in ozonized sludge. The dewaterability of ozonized sludge, assessed by capillary suction time (CST) and specific resistance to filtration (SRF), deteriorated with ozone dose. The optimal dose of cationic polyelectrolyte increased with increasing ozone dose. The production rate and the accumulated amount of methane gas of ozonized sludge were also higher.

scholarly journals Optimization of microalgae harvesting by sedimentation induced by high pH

2020 ◽  
Vol 82 (6) ◽  
pp. 1227-1236
Author(s):  
Luan de Souza Leite ◽  
Luiz Antonio Daniel
Keyword(s):  
Large Scale ◽  
Mixing Time ◽  
Operational Parameters ◽  
Microalgae Harvesting ◽  
Operational Optimization ◽  
Physico Chemical ◽  
Apparent Color ◽  
Wastewater Quality ◽  
Practical Guidelines ◽  
Viable Method

Abstract Microalgae harvesting is a major hurdle for the production of high-value microalgal bioproducts on a large scale. Among harvesting techniques, pH-induced sedimentation stands out as an inexpensive and technically viable method. Nevertheless, there is little information available on the application of this method for microalgae cultivated in wastewater. In this context, the present study investigated the optimization of sedimentation parameters for Chlorella sorokiniana harvesting from wastewater. Parameter optimization was statistically determined by the response surface methodology. The optimal values included a velocity gradient of 250 s−1, mixing time of 10 seconds, and pH of 12, which enabled microalgae harvesting efficiencies of more than 97.8%. These optimal parameters also showed resilience through the physico-chemical variation of the photobioreactor effluent. Furthermore, wastewater quality improved significantly after microalgae harvesting. High removal was found for turbidity (97.9–98.3%), apparent color (92.2–97.2%), total Kjeldhal nitrogen (91.0–94.4%), and total phosphorus (92.8–98.6%). Centrifugation, as the dewatering method, and its operational parameters were also evaluated. Sedimentation followed by centrifugation increased the initial microalgae concentration by about 123 times. This study shows the importance of operational optimization and the results can be used as practical guidelines for microalgae harvesting on a large scale.

On the role of aluminium hydroxide in the conditioning of an alum sludge

1998 ◽  
Vol 38 (2) ◽  
pp. 33-40 ◽  
Author(s):  
E. N. Papavasilopoulos ◽  
D. H. Bache
Keyword(s):  
Specific Resistance ◽  
Polymer Adsorption ◽  
Optimum Dose ◽  
Capillary Suction ◽  
Viscosity Measurements ◽  
Nonionic Polymer ◽  
Saturation Coverage ◽  
Prime Determinant ◽  
Alum Sludge

This study dwells on the optimum dosage of a nonionic polymer during the conditioning of an alum sludge arising from the treatment of a coloured, upland water. Dewaterability was investigated through Capillary Suction Time (CST) and Specific Resistance to Filtration (SRF) tests, together with viscosity measurements on the liquid phase of sludge. The optimum dose associated with CST and SRF was 1.5 kg/T while for the case of viscosity behaviour it was 2.0 kg/T. From polymer adsorption studies on the sludge, it was shown that the optimum doses associated with the viscosity measurements were linked to a dose at which the adsorption capacity reached a saturation value (1.8 kg/T). The SRF and CST optima were found to correspond to a state of 70-85% of the saturation coverage. Parallel adsorption tests on alum sludge and pure precipitate showed that polymer adsorption on the precipitate was the prime determinant of the adsorption characteristics of the sludge and suggested that the optimum dose was linked to the mass of precipitate present in the sludge.

Does the dose of leucovorin (LV) matter with 5-fluorouracil (5FU) in colorectal cancer (CRC)?

2016 ◽  
Vol 34 (4_suppl) ◽  
pp. 708-708
Author(s):  
James Joseph Biagi ◽  
Nadia Coakley ◽  
Craig Earle ◽  
Charles Erlichman ◽  
Anthony L.A. Fields
Keyword(s):  
English Language ◽  
Expert Panel ◽  
Research Question ◽  
Disease Free Survival ◽  
Progression Free Survival ◽  
Optimal Dose ◽  
Convincing Evidence ◽  
Optimum Dose ◽  
High Dose ◽  
Free Survival

708 Background: In June 2015 Cancer Care Ontario convened an expert panel to determine if there is an optimum LV dose in 5FU-LV combinations for the treatment of CRC. This request arose out of observed variation in LV dosages between some cancer centers. The research question was effect of LV dose on overall survival (OS), progression free survival (PFS), disease free survival (DFS), response rate (RR) and adverse events/toxicity, given a constant dose of 5FU. Methods: A systematic search was conducted for guidelines (GL) and comparative trials; eligibility included English language, with > 30 patients, that examined different doses of LV where dose of 5FU was not varied. Assessment of studies for inclusion was completed by 4 reviewers. Results: We identified 5 GL, 0 systematic reviews and 12 trials that defined a LV dose in combination with 5FU. None of the GL informed an optimal dose of LV. RR was assessed in 10 trials; 4 showed trends to higher RR with higher LV dose, but differences were not statistically significant (SS) between arms. PFS or DFS was reported in 6 trials and was similar between arms. Time to recurrence reported in one trial that included bevacizumab (BV) was longer in the high dose LV group that was SS. OS was addressed in 10 studies: no difference found in 7 studies; in one RCT OS was longer with the higher dose LV 55 vs. 45 months (p not reported); in one retrospective study OS was 23 vs. 20 months in favor of high dose LV (p not reported); one study of LV and BV had longer OS vs. lower dose LV at 26 vs. 21 months (SS). Toxicity: higher dose LV was associated with greater toxicity in 3 of 4 studies that reported stomatis, and increased rates of diarrhea in 9 of 11 trials. Meta-analysis was not appropriate as studies were too heterogeneous. Conclusions: There is no convincing evidence to identify an optimum dose of LV to be used in 5-FU/LV combinations. Amongst studies that did show a difference the trend was improved survival in favor of the higher dose. Similarly, differences in toxicities when identified were consistently greater with the higher dose LV. The expert panel concludes that the existing literature provides insufficient data to suggest that chemotherapy protocols should deviate from standard protocol doses.

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