Analysis and Kinetics of the Sequencing Batch Reactors

Fundamental analysis and kinetics of treatment reactors are major topics in environmental engineering literature. These fundamental topics in reactor processes are well known for the ideal batch reactor, the continuous stirred tank reactor, and the plug flow reactor. The sequencing batch reactors (SBRs) are relatively new in the field, but are widely used. Despite the wide application of sequencing batch reactors in the field, information is lacking on the fundamental analysis and kinetics, especially with comparison to the ideal batch reactor. This report presents analysis and kinetics of the sequencing batch reactors and compares the kinetics equations developed with those of the ideal batch reactor especially for zero-order, first-order, and second-order reactions. A significant result is that the SBRs’ equations for the three re- action orders analyzed become the equations for the ideal batch reactor if the entire reactor volume of a sequencing batch reactor is decanted. The fundamental analysis and the kinetics presented will help enhance the understanding of the sequencing batch reactors and their use in waste treatment

Anaerobic sequencing batch reactor treatment of low strength wastewater

The treatment of low strength wastewater at various temperatures and hydraulic retention times in the anaerobic sequencing batch reactor (ASBR) was studied. The studies involved the use of four identical, laboratory scale anaerobic sequencing batch reactors (ASBRs), each having a working volume of six liters. One of the reactors was maintained at a 48 hour hydraulic retention time HRT, the second at a 24 hour HRT, the third at a 16 hour HRT and the fourth at a 12 hour HRT. A synthetic substrate (non fat dry milk; NFDM) was treated at concentrations of 1000, 800, 600 and 400 mg/L COD in each of the four reactors and at temperatures of 35, 25, 20 and 15° C. The substrate concentrations resulted in COD loadings ranging from 0.2 to 2.0 g/L/d and corresponding BOD[subscript]5 loadings ranging from 0.1 to 1.0 g/L/d. The objective was to evaluate the performance of the ASBR treatment of low strength wastewater at various temperatures and hydraulic retention times;It was hypothesized that the high biological solids holding capability of the ASBR, a new high-rate anaerobic reactor, would foster efficient treatment of low strength wastewater, even at ambient temperatures. Various parameters were analyzed to evaluate the performance of the reactors as well as their operational conditions. The parameters included: organic (COD) removal, effluent solids, system mixed liquor suspended solids, volatile fatty acids content of the systems, food-to-microorganisms ratio, pH, alkalinity, biogas production, sulfate reduction and the formation of granules. The removal of COD at the various substrate concentrations, temperatures, and hydraulic retention times was the primary indicator used for evaluating the performance of the reactors;Results show soluble COD removals at the 48 and 24 hr HRTs in excess of 90% at all feed concentrations and temperatures. Soluble COD removals in the short (16 and 12 hr) HRT systems were also at about 90% for the lower COD strengths of 600 and 400 mg/L at all temperatures. Based on total COD removals, the performance was around 90% at the 48 and 24 hr HRTs across the entire range of temperatures. At the 16 and 12 hr HRTs, performance declined but still remained in excess of 80% at all temperatures for substrate concentrations of 600 and 400 mg/L COD;The results of this research show that the ASBR process is an efficient system for the treatment of low-strength wastewater, even at ambient temperatures

Family and consumer sciences teachers\u27 attitudes and practices concerning parent involvement in the educational process

The purpose of the study was to assess junior and senior high school family and consumer sciences teachers\u27 attitudes and practices concerning parent involvement in the educational process. Several specific objectives and variables of interest, including attitudes, practices, efficacy, and perceived level of support from colleagues for parent involvement were assessed. Using a mailed questionnaire titled, School-Home Partnerships Survey, the study surveyed 168 teachers randomly selected from a list of 682 junior and senior high school family and consumer sciences teachers, obtained from the Iowa Department of Education;Methods of data analyses consisted of descriptive and inferential statistics, including path analysis. Results indicated that overall, the teachers did not project positive attitudes toward parent involvement. Teachers judged all the parent-involvement practices as somewhat or more than somewhat important, with practices involving communicating with parents judged as very important, while those that called for parents to be involved in the decision-making process were judged to be of little importance;With regard to personal teaching efficacy, teachers displayed a somewhat weak sense of personal teaching efficacy. This condition seemed to be due to perceived lack of support for their work from their principals and other teachers in their schools and perceived inadequate teacher training education. The teachers believed that there is a general support from others for parent involvement in the educational process of children. Better parent-involvement practices by the teachers was predicted by adequate training in parent involvement, positive attitudes about parent involvement through in-service education, stronger sense of personal teaching efficacy, and the belief that others in their schools have a higher level of support for parent involvement;Compared to teachers with bachelor degrees, those with masters degrees expressed significantly more positive attitudes about parent involvement. The teachers indicated parent/teacher conferences as the most successful parent-involvement practice. To help them strengthen the partnerships between schools and homes, the teachers indicated that they needed in-service education, seminars, workshops, college courses, and communication skills training to help them implement better parent-involvement practices. A significant number of teachers saw working parents and teachers\u27 lack of time as the two most important reasons they could not have stronger links between themselves and the parents of their students

Using a Hybrid Instructional Model in Teaching and Learning

Hybrid courses allow for in-person learning communities combined with the convenience and reflective nature of online learning. This roundtable will provide an opportunity to share educators’ experiences and techniques in implementing the hybrid model to facilitate student learning

Response variation of Chladni patterns on vibrating elastic plate under electro-mechanical oscillation

Fine grain particles such as sugar, sand, salt etc. form Chladni patterns on the surface of a thin plate subjected to acoustic excitation. This principle has found its relevance in many scientific and engineering applications where the displacement or response of components under the influence of vibration is vital. This study presents an alternative method of determining the modal shapes on vibrating plate in addition to other existing methods like the experimental method by Ernst Chladni. Three (3) finite element solvers namely: CATIA 2017 version, ANSYS R15.0 2017 version and HYPERMESH 2016 version were employed in the modelling process of the 0.40 mm x 0.40 mm plate and simulation of corresponding mode shapes (Chladni patterns) as well as the modal frequencies using Finite Element Method (FEM). Result of modal frequency obtained from the experimental analysis agreed with the FEM simulated, with HYPERMESH generated results being the closest to the experimental values. It was observed that the modal frequencies obtained from the FEM and experimental approach increased as the excitation time increased. ANSYS R15.0 and HYPERMESH software clearly represented the modal lines and mode shapes for each frequency which CATIA software was somewhat limited. This study has shown that FEM is an effective tool that can save time and energy invested in acoustic experiments in determining modal frequencies and patterns.Keywords: Vibration, Chladni patterns, Modal frequency, Thin plate, Experimental analysi

Modelling and simulation of high density polyethylene liner installation in engineered landfill for optimum performance

Geomembrane liner is an important part of a landfill system that must be selected and installed properly to avoid high induced stresses and imperfections. Considering a fixed HDPE liner thickness of 2mm and variable masses in this study, the liner was modelled and simulated for 27 scenarios using Solidworks and Artificial Neural Networking approach. Static analysis was further performed on the Solidworks model under a distributed load of 4000kg in properly aligned and improperly aligned conditions to the base and side walls of a landfill system. The minimum stress and width of imperfection obtained from the Solidworks simulation was 77MPa and 34mm while 65MPa and 67mm was obtained from the ANN simulation. The liner failed outrageously in the improperly aligned condition with maximum induced stress of 3,606.521MPa, but no sign of failure was observed for the properly aligned condition which the maximum stress (0.018Mpa) was quite low. This investigation can serve as a guide towards proper installation of geomembrane liners for optimum performance in landfill applications.Keywords: Solid waste, engineered landfill, Geomembrane liner, Installatio

Housing and Mobility Toolkit for San Mateo County

Since the end of the Great Recession, San Mateo County has attracted new workers at a record rate without building anywhere near enough housing. This jobs-housing imbalance drives the cost of housing up and forces many moderate and lower-income employees and their families out of the County. A lack of access to quality affordable housing in the County and the entire Bay Area along with limited transportation options means that an increased number of employees drive in and out of the County every workday. The resultant congestion, gridlock, and long commutes along with other negative environmental, social, and economic impacts create a major concern for communities in the County and beyond. Clearly, this problem has two distinct but interrelated dimensions: housing development and transportation planning. A select group of Mineta Transportation Institute (MTI) Research Associates worked closely with representatives from the San Mateo County Home for All initiative to help address this challenge by developing a toolkit of successful case studies with a holistic approach to housing development and transportation planning

Physical Composition of Municipal Solid Waste and Nutrient Contents of Its Organic Component in Uyo Municipality, Nigeria

This research was conducted within Uyo metropolis, Nigeria. Three designated dumpsites of municipal solid waste (MSW) were randomly selected for the collection of samples for analysis of the physical and macronutrient contents of their organic fraction. After the waste was sorted, its physical components were determined to be: organic materials (73.7%), plastics/polythene (12.9%), cans/metals (4.3%), bottles/glasses (4.2%), clothes/shoes (4.3%), and ceramics (0.6%). Laboratory analysis of the organic components of the waste indicated that the mean nitrogen (N), phosphorus (P), and potassium (K) contents were 11.0, 3.2, and 10.7 g kg−1, respectively. The mean contents of other elements were calcium (Ca) (87.7 g kg−1), sodium (Na) (18.4 g kg−1), and sulfur (S) (2.3 g kg−1). The mean organic-matter content of the organic components of the waste was 223.7 g kg−1. Both the physical and macronutrient contents of the waste differed from one location to another within the municipality. The high content of organic matter and some essential macronutrients in the waste suggest its high value for use in the production of organic and organo-mineral fertilizers for sustainable agricultural development

Preliminary Evaluation of Effects of Herbicide Types and Rates on Growth and Yield of Cassava (Manihot esculenta Crantz)

A field experiment was conducted at the University of Uyo Teaching and Research Farm, located at Use-Offot, Uyo, Akwa Ibom State of Nigeria between September, 2007 and August, 2008.cropping season. to evaluate the effects of type and rate of herbicides on growth and yield of cassava (Manihot esculenta Crantz). The experiment was laid out in a randomized complete block design with a split plot arrangement and replicated three times. The main treatments were types of herbicides viz: Primextra (Atrazine +Metolachlor) (2-chloro-4(ethylamino-6-(isopropylamino-s-triazine and 2-chloro-N-(-2-ethyl-6-methy-phenyl-N-(2-methozylmethylethyl acetamide), Atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino) s-triazine) and Diuron (N-(3,4-dichlorophenyl)-N, Ndimethlurea, while the sub-treatments were rates of application of the herbicides (1.0, 2.0, 3.0, and 4.0 kga.i ha ֿ◌ ¹ applied as preemergence as well as control treatments where no herbicide was applied. Results showed that type and rate of herbicides had significant effects on , stand establishment, plant height leaf area index, number of tubers /stand, tuber length(cm), weight of tuber per plant and tuber yield(t/ha) at (P<0.05). Primextra at 2.0kga.i/ha had the significantly superior growth and yield (19.8tha) than Atrazine (17.3t/ha) and Diuron (16. 8t/ha). Based on the findings, this study suggests that Primextra at 2.0kga.i/ha is effective for weed control in cassava due to low phytotoxicity, better crop growth, and higher storage root yield