Factors and impacts of informal settlements residents' sanitation practices on access and sustainability of sanitation services in the policy context of Free Basic Sanitation

Through the Free Basic Sanitation (FBSan) service policy, many informal settlements in South Africa have been provided with basic sanitation facilities. However, access to these facilities remains challenging for many residents. These challenges have compelled residents to adopt a range of alternative sanitation practices. Through interviews, observation and focus group discussions in five informal settlements in the Western Cape, South Africa, 383 randomly selected respondents identified factors that shape their sanitation practices and how these practices impact on access to, and sustainability of sanitation services in the policy context of the FBSan. Residents' sanitation practices include the use of buckets, porta-potties, plastic bags, and existing facilities within and outside their settlements for either defecating or discharging the bucket contents and open defecation. These sanitation practices are informed by factors including safety concerns, poor conditions of the facilities, lack of privacy and choice. These findings suggest that the provision of facilities through the FBSan policy should consider the multiple and varied needs of residents, practices and conditions of their settlements prior to the selection and deployment of facilities to informal settlements in South Africa

Flow of non-newtonian fluids in open channels

Dissertation (DTech (Civil Engineering))--Cape Technikon, Cape Town, 2003Flume design for homogeneous non-Newtonian fluids is problematic and not much research has been conducted in this field. This application is industrially important in mining where slurries have to be transported to processing or disposal sites at higher concentrations because water is becoming a scarce and expensive commodity. This thesis addresses the problem of flume design and develops predictive models for the laminar, transitional and turbulent flow behaviour of non-Newtonian fluids in rectangular open channels. The relevant literature pertaining to Newtonian and non-Newtonian pipe and open channel flow is reviewed and research aspects are identified. A unique test facility was designed, constructed and commissioned for this project. The facility includes a 5 m-long by 75 mm-wide rectangular tilting flume, as well as a 10 m by 300 mmwide rectangular tilting flume that can be partitioned to form a 150 mm wide flume. The flumes are in series with an in-line tube viscometer which has tubes of diameter 13, 28 and 80 mm. The experimental investigation covers a wide range of widths (75 mm-300 mm), slopes (1º-5º), flow rates (0.05 l/s-45 l/s), relative densities (1.0067-1.165), volumetric concentrations (0%-10%), and yield stresses (0-21.3 Pa). The fluids tested are kaolin and bentonite slurries and CMC and Carbopol polymer solutions. The resulting database of empirical flow behaviour enabled the identification of the important flow behaviour characteristics. Existing models are compared and evaluated using the experimental database compiled for this thesis and it is concluded that no model exists to predict the database compiled for the various materials from laminar flow through the transition region into turbulence. For the correlation of laminar flow data, a Reynolds number was developed from the Reynolds number proposed for pipe flow by Slatter (1994). Using this Reynolds number, all the laminar flow data available was collapsed onto the 16/Re line on a standard Moody diagram. Criteria were developed to predict the onset of transition and the onset of ‘full turbulence’. These criteria are functions of the Froude and Reynolds number as well as the viscous characteristics of the fluids. These models performed better than the methods proposed by Naik (1983) and Coussot (1994), which were based on the Hanks criterion. A turbulent flow model was developed based on the turbulent model presented by Slatter (1994) for pipe flow. Flow predictions using this model were more accurate than those presented by Torrance (1963), Naik (1983), Wilson and Thomas (1985), and Slatter (1994). The new models were tested with the database compiled for this thesis as well as with two published data sets, one by Naik (1983) and the other by Coussot (1994). The new flow models predicted all the available data within acceptable limits, providing a basis for design. A new and experimentally validated design protocol is presented for the design of rectangular non-Newtonian open channel flow in laminar, transitional and turbulent flow

Saldanha Bay ore jetty : a study of berthing impacts

Thesis (Masters Diploma (Civil Engineering)--Cape Technikon, Cape Town, 1987Between December 1982 and January 1984 the berthing impacts o~ 50 ore carriers were monitored at the Saldanha Bay ore-jetty. The actual displacement o~ the monitored vessels ranged between 60 and 263 kilotonnes. Only 507. o~ the monitoring runs yielded complete sets o~ data. Approach velocities recorded were high and the design limits were exceeded several times resulting in ~enders being de~lated on ~our occasions. The added mass coe~~icient ~or each impact was calculated. The actual values o~ C" varied between 1 and 7. This agrees with values ~ound in literature. Some o~ the\high values could be attributed to inaccuracies in the measurement techniques. From the values obtained ~or added mass it seems that the value used in the design was very low and that a unitary value ~or CH is not very satisfactory

Non-Newtonian flow rate measurement using a rectangular notch

CPUT Research Da

A review of Newtonian and non-Newtonian flow in rectangular open channels

Flumes are ubiquitous throughout the mining and minerals processing industries as well as being used in the polymer processing and pulp and paper industries. With the increased demand for the transport of highly concentrated slurries in rectangular open channels, there is an impetus for a better understanding of the role of rheology in flow hydraulics. Until recently, design of such channels has been based on either the Chézy or Manning equations used for modelling open channel flow of Newtonian fluids. This has been done for modelling turbulent flow of low concentrated slurries with some success. However, this is not the case for highly concentrated slurries where the flow in the channel is no longer turbulent. Unlike Newtonian fluids, work carried out on flow of pseudo-homogeneous, non-Newtonian fluids in open channels is somewhat limited. Moreover, these results have been published in a variety of sources. This paper attempts to give a critical review of the work carried out on Newtonian and non-Newtonian flow of pseudohomogeneous non-settling slurries in rectangular open channels. A comparison is also made of the models based on power law, Bingham plastic and Herschel-Bulkley fluids for laminar and turbulent flow in rectangular open channels

Highly concentrated emulsions: Role of droplet size

The problem of droplet size dependence on rheological properties of highly concentrated emulsions was studied. Changes in droplet size distribution were achieved by multi-pass flow through a small orifice set as the outlet of a piston-chamber pumping instrument, and extended elongation of droplets combined with the transient-transition flow regime (laminar/turbulent) at the outlet of the orifice provided the shift of the droplet sizes to the smaller-size side of the distribution. Their distributions were wider and of the logarithmic-normal distribution type. Two models were proposed and used to fit the refinement evolution and the width of distributions respectively. The droplet size versus number of pumping cycles was expressed by the fitting parameters, θD, θω, Dcrit., ωcrit., and C, which, in turn, gave a clear estimation of factors that influence refinement during pumping. These factors involved surfactant type and surfactant concentration, where higher surfactant concentration induced higher efficiency with regard to droplet disruption. The most important part of the result of the investigation is, however, the experimental proof that the shear modulus versus droplet size is not necessarily expressed by a linear reciprocal dependence, but by an exponent equal to 2. It was shown that the stability of highly concentrated emulsions in shearing is determined by some critical value of deformation with reference to the yielding conditions. This value on average equalled 0.07 for all samples under investigation

Application of ultrasound doppler technique for inline rheological characterization and flow visualization of concentrated suspensions

Ultrasonic velocity profiling (UVP) is a technique that can measure an instantaneous one-dimensional velocity profile in a fluid containing particles across the ultrasonic beam axis or measurement line. A method for in-line rheometry combining the UVP technique with pressure difference (PD) measurements (UVP + PD), was developed and improved at SP − Technical Research Institute of Sweden and the Cape Peninsula University of Technology, South Africa. The UVP + PD methodology allows measurements that are not possible with common rheometers such as radial velocity profiles and yield stress directly in-line and under true dynamic process conditions. Furthermore, it has advantages over commercially available process rheometers and offline instruments in being non-invasive, applicable to opaque and concentrated suspensions, and having small sensor dimensions. It has been evaluated for several potential industrial applications including paper pulp, foods, transient flows, and model mineral suspensions. Similarly, the UVP technique can be applied to an open-channel flow by combining flow depth measurements to obtain rheological properties in-line. Industrial fluids, such as thickened pastes, commonly found in tailings transportation exhibit wide particle size distributions, large particle sizes, and very high viscosities. These industrial fluids cause strong attenuation of the ultrasound energy, which can significantly distort velocity profiles measured with the UVP technique or even make it impossible to conduct flow measurements. Initial results obtained in concentrated cement pastes and grouts (bentonite and kaolin clay) showed that UVP is a feasible and promising technique for flow characterization in viscous fluids

Friction factor-Reynolds number relationship for laminar flow of non-Newtonian fluids in open channels of different cross-sectional shapes

The effect of channel shape on the friction factor-Reynolds number relationship for laminar, open channel flow of three non-Newtonian fluids was investigated. For each channel shape, the data can be described by a general relationship, f=K/Re where f is the Fanning friction factor and Re is the appropriate Haldenwang et al. (2002) Reynolds number corresponding to the flow curve model used to describe the non-Newtonian behaviour exhibited by the test fluid. The K values were found to be 14.6 for triangular channels with a vertex angle of 90°, 16.2 for semi-circular channels, 16.4 for rectangular channels and 17.6 for trapezoidal channels with 60° sides. These K values were found to be in line with those reported by Straub et al. (1958) and Chow (1959) for open channel flow of Newtonian fluids as opposed to the assumption made by Haldenwang et al., 2002 and Haldenwang et al., 2004 of using a constant value of 16 based on the pipe flow paradigm for all channel shapes

The Effect of a Blended Polycarboxylate Superplasticizer on the Rheology of Self-Compacting Concrete Paste

High-strength-performing concretes (HSPC) have been used extensively due to new building requirements and their special properties suitable for modern cities. Superplasticizers (SPs) are essential components in the mix design of these concretes since they control their fresh properties and improve durability. In practice, superplasticizers are used to achieve a desired workability without increasing the water content by dispersing agglomerated cement particles. The aim of this research was to investigate the effectiveness of a blended polycarboxylate (PCE) superplasticizer on the rheological behavior for three different cements. It was found that two SP agents with the same molecular structure but with different weight and side-chain length provided an SP product that had a greater effect on the rheological properties of the cement paste. Yield stress values remained unaffected in the presence of blended SP with an SP fraction above 50% and with long side chains while its adsorption ability increased with the decrease in SP fraction with shorter side chains and lower molecular mass

Experimental database for non-Newtonian flow in four channel shapes

The database for non-Newtonian flow in rectangular open channels developed by the Flow Process Research Centre at the Cape Peninsula University of Technology was recently extended to include the testwork on non-Newtonian flow in open channels of semi-circular, triangular and trapezoidal cross-sections. As for flow in rectangular open channels, the flow of carboxymethylcellulose solutions and aqueous kaolin and bentonite suspensions was investigated in these open channels at angles varying from 1° to 5°. The flow curve data for these three fluids were best represented by the power law, Bingham plastic and Herschel–Bulkley models, respectively. The research methodology in the use of this extended database to study laminar, transitional and turbulent non-Newtonian open channel flows is described. It is hoped that this database will be a useful resource to researchers working in the field of non-Newtonian open channel flow