Umgeni Water Amanzi

Chemical contaminants that occur in drinking water are not usually associated with acute health effects when compared to microbial contaminants and are usually given a lower priority. Those that are of concern have cumulative toxic properties such as metals and substances that are carcinogenic. Some of these potentially hazardous chemical contaminants are a consequence of the treatment chemicals themselves e.g. organic polyelectrolytes used as coagulant aids in water treatment. The presence of residues of the un-reacted monomer in these polyelectrolyte products is a cause for concern. Historically, inorganic coagulants such as aluminium sulphate and ferric chloride have been used as coagulants/flocculants in the treatment of drinking water. The residual amounts of these chemicals were easy to detect and to control using readily available standard methods. The increasing use of polyelectrolytes has created a problem for the potable water industry as there are no readily available methods for the determination of residual polyelectrolyte concentration. This study aims at extending existing analytical techniques and comparing them to determine results that are most accurate and reliable to the quantification of residual polyelectrolytes.

A blend of ferrous chloride and ferric chloride (FeCl2-FeCl3) was simultaneously dosed into an activated sludge system at pilot scale in order to test the effect on biological P removal. Additional removal due to chemical precipitation was measured as the difference in system P removal between parallel test and control systems. Both systems strongly exhibited biological excess P removal (BEPR). The extent of P release in the anaerobic reactors of the two systems was compared by mass balance, as one indicator of the relative "magnitude" of BEPR. Phosphorus fractionation of the mixed liquor also served as an indicator of the biological and chemical mechanisms. Evidence was found that the BEPR mechanism is partially inhibited by simultaneous FeCl2-FeCl3 addition, even in the absence of effluent phosphate limitation. However, the degree of inhibition was relatively low, ranging from 3 to 25% (approximately) for Fe doses in the range ca. 10 to 20 mg/ℓ as Fe, with an average system P removal of 14 to 18 mgP/ℓ in the control. FeCl2-FeCl3 dosing in this range was sufficient to produce additional P removal of the order of 1 to 8 mgP/ℓ over periods of one to seven sludge ages per experimental period, depending on the experimental conditions. Sustained operation of the BEPR mechanism in the presence of FeCl2-FeCl3 was possible over a continuous period of seven sludge ages, under conditions in which effluent phosphate was at least partially limiting. Under such conditions, the chemical and biological mechanisms appear to be "disadvantaged" to approximately the same extent, as evidenced by the apparent stoichiometry of Fe: P for the chemical precipitation and magnitude of the poly P containing fractions measured for the biological mechanism. This suggested that the biological mechanism is able to compete effectively with the chemical mechanism under conditions of low reactor phosphate concentrations (~1 mgP/ℓ orthoP) for sustained periods. However, the presence of simultaneous chemical precipitant significantly reduces the extent to which the biological P removal potential is utilised under P-limiting conditions. This could explain the difficulty sometimes reported in the control of full-scale activated sludge systems with simultaneous precipitant addition where a very low effluent P concentration WaterSA Vol.27(2) 2001: 117-134

Reliable indicators of water quality and river health are often difficult and expensive to derive. This paper reports on a process to develop a low technology, scientifically reliable and robust technique to monitor water quality in rivers and streams. With these requirements in mind the authors set about developing a simplified method of biomonitoring based on the tried and tested SASS (South African Scoring System) technique. This involved reducing the taxonomic complexity of SASS to a few aquatic invertebrate 'groupings' which would act as surrogates for the complete suite of SASS taxa. To be efficient the technique had to satisfy the following requirements: 1. minimise the number of aquatic invertebrate groupings necessary to perform miniSASS; 2. aquatic invertebrate groups should be easily identifiable; 3. the method should be robust and produce results comparable to the full SASS technique; and 4. be geographically widely applicable. These requirements were met in this development and for a large set of data (>2 000 records) covering the Mpumalanga / Eastern Seaboard (Umgeni Water) and Western Cape regions there appear to be no statistically significant differences between SASS and miniSASS scores. However, once the data becomes split into various water quality classes (as defined in the Draft Procedures for the Water Quality Reserve, Department of Water Affairs and Forestry 2002) statistically significant differences between SASS and miniSASS become apparent. Nonetheless, these differences are relatively small and are usually less than 1 ASPT score different. Potentially, every school, environmental or community group in the country could become a monitoring cell, and with this geographical spread use the miniSASS tool as a 'red flag' for the identification of aquatic pollution sources and events in their immediate environment. The parallel and supporting initiative, to be able to enter this 'real aquatic biomonitoring data' onto an internet web-based mapping programme (see www.riverhealth.co.za), extends the application of the resource making networking and broad based catchment water quality monitoring a real possibility. miniSASS can therefore be used with some confidence, producing data which vary slightly from SASS, but which is sufficiently accurate to be of value to all stakeholders with an interest in river health. The increased opportunity for communities to become involved, use a scientifically valid tool and undertake real biomonitoring of their river systems is probably the most important aspect of the development of this resource. Through this involvement, live, real-time monitoring and investigation of pollution sources in their systems is possible, and the opportunity for improved environmental management a reality.

The assessment of biota in rivers is a widely recognised means of determining the condition or ‘health’ of rivers. Benthic macroinvertebrates, in particular, are recognised as valuable organisms for bioassessments, due largely to their visibility to the naked eye, ease of identification, rapid life cycle often based on the seasons and their largely sedentary habits. Numerous bioassessment techniques have been developed over the last three decades, varying in complexity and region of implementation. South Africa has an exemplary history in this field, culminating in the refinement of invertebrate and other techniques and their application in a National River Health Programme. The method presented here is a refinement of the highly successful SASS (South African Scoring System) method developed by Chutter (1994), which forms the backbone of this programme. This paper takes the method to a level where it can, and has been, accredited to ISO standards. The principal changes made include the tighter definition of the technique and the sampling and analytical methods, as well as the introduction of quality control procedures. Some changes have also been made to the list of invertebrates used in this method. Field trials were conducted to test the variability of the method. Of the various indices available to the method, the Average Score per Taxon (ASPT) is the most consistent over all biotopes (lowest CV%). On the other hand, of the biotopes examined the Gravel/Sand/Mud (GSM) combination is the most variable with respect to the SASS Score and number of taxa encountered. The spatial variability on a reach of river with similar water quality characteristics was found to be statistically negligible. However, one generally finds that statistically significant differences occur between the SASS Scores and the number of taxa counted by different operators. The ASPT, on the other hand, is a more consistent and repeatable measure of river health assessment and, within a given reach of river and considering all biotopes, the differences in results produced by different operators were statistically negligible. The results highlight the need for appropriate competency-based training and consistent application of the method.

Abstract Recent methods employed for the analysis of algal toxins have focused on high performance liquid chromatography. However these methods suffer from poor resolution, poor efficiency, and long analysis times. This study involves the investigation of a number of toxins including nodularin, microcystin LR, YR, and RR which are cyclic peptides produced by strains of blue‐green algae. The electroseparation mode was micellar electrokinetic capillary chromatography (MECC) using a borate buffer containing sodium dodecyl sulfate (SDS) as the surgactant of choice. The method was optimized with standard toxin compounds and employed for the screening opf toxins in supercritical fluid extracts (SFE) of freeze‐thawed algal scum samples.

Located in the province of KwaZulu-Natal, South Africa, the Mgeni River catchment provides the potable water resources for nearly two million people, in an area of approximately 4 400 km2. The river system is well developed and impounded, but increasing population pressures in the catchment are placing greater demands on this critical water resource resulting in increasing loads of nutrients, faecal bacteria and suspended solids. Umgeni Water and the Department of Water Affairs and Forestry are developing an affordable and practically implementable plan to manage the water quality on an integrated catchment basis, encompassing demographic, land-use and management considerations. The development of the plan is discussed and information on the water management related issues provided. A multidisciplinary approach has proved essential, facilitated by the development of a GIS-based system to manage and utilize the information from the study. Establishment of communication links with interested and affected parties has been critical, as has the clarification of their roles and responsibilities in dealing with identified pollution issues. Future development within the catchment is considered and the implementation of the management plan is discussed against the background of the Reconstruction and Development Programme.