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Solid waste management in low income developing countries is generally the responsibility of the official sector, such as municipal corporations. However, there are extensive inputs from the from the private informal sector in waste collection, separation and recycling. Four different activities in the private informal sector have been studied to identify the potential of their integration with the official system. Where integration means that the official sector accepts those practices and incorporates them into existing practices and future plans. All the cases have been selected from the city of Karachi, Pakistan. A multiple case study approach was adopted to assess the potential for integration, constraints to integration, attitudes, relationships and dependencies. It has been concluded that under the present circumstances, the private informal activities in solid waste management cannot be integrated formally with the official system. The main constraints to integration are public and municipal attitudes, the interrelationships and dependencies, interference by politicians and the lack of understanding on the wide range benefits of integration. Future models must be developed on the private informal practices within the official systems, such as primary collection of waste through municipal sweepers. A number of benefits of the private informal practices were also highlighted by the research which may be considered as opportunities once integration takes place. The recommendations include a number of actions and potential policy changes which could be done to promote integration and a better partnership between the private informal and the public sector.

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The aiin of this research is to investigate the process by which techniques for the remedial treatment of contaminated land evolve. This is accomplished through the study of the relationships between: environmental policy and law; industrial practice; and research and development. Previous studies of the barriers and driving forces of such development have tended to be from a technical point of view. However, this research aims to explore the dynamics of technological innovation. Structured interviews, questionnaires and case studies were used to collect qualitative data from a cross section of the contaminated land industry. Interview transcripts were produced and subsequently, after consultation with the interviewees, presented as synoptic summaries including contextual information. Ile interview, questionnairea nd case study information is critically assessedw ith referencet o relevant contextual information. The following areas are discussed: public opinion; regulation and policy; uncertainty and development; political lobbying; measures intended to stimulate the use of treatment techniques; and, the relationship between vendors, consultants and property developers. It is concluded that: the development of treatment techniques is dependent upon the incremental accumulation of knowledge by politicians, scientists and the developers of remedial treatment techniques and that differences in these phenomena can result in "friction" in relation to the development of remedial treatment techniques. Particular emphasis is placed upon the adoption of pragmatic, deregulatory approachest o the regulation of contaminatedl and and the adoption of risk managementa pproachesI.t is emphasised that uncertainty relating to the performance of treatment techniques remains, particularly in relation to treatment time and cost. It is concluded that the commercial success of a treatment technique depends as much upon its ability to comply with the managerial constraints on the redevelopment process as upon its technical proficiency.

Landfill leachate with its variable and complex characteristics poses a well established threat to the environment. Enhancement of the environmental quality through the minimization of the leachate problem should therefore be the major objective of good landfill management. The need to control and manage landfill leachate has resulted in various treatment alternatives which include both biological and physical-chemical processes. The research described in this thesis discusses the feasibility of biological and physical-chemical treatment of leachate based on laboratoryscale reactors. After a short introduction, a review of the relevant literature on solid waste disposal including landfilling, leachate generation and the treatment alternatives was presented. Comparative experimental studies were then carried out using an aerobic rotating biological contactor (RBC), an upflow anaerobic filter (UAF) and an activated carbon (AC) adsorption column for treating landfill leachate. The effect of a range of parameters on the performance and operation of the RBC, the UAF and the AC column has been evaluated in the study From the experimental results, an RBC was found to achieve a better performance when treating a low strength (LS) leachate, whereas a high strength (HS) leachate would be much better treated by a UAF. For the LS leachate treatment, a COD removal of 80% at a loading rate of 6 kg COD/m3.d was achieved by the RBC as compared to only 60% by the UAF. Whereas for the HS leachate the RBC achieved a COD removal of only 50% at the loading rate of 14 kg COD/m3.d as compared to 60% by the UAF. Direct physical-chemical treatment process in treating leachate using an AC adsorption was also investigated. The results obtained showed that the adsorption process was not capable of achieving the desired effluent requirement, with 20% residual organic fractions still remaining in the effluent. The need to remove this biodegradable organic matter by biological processes was found to be necessary. It is suggested that to achieve satisfactory treatment, anaerobic UAF treatment of leachate followed by aerobic RBC and a final polishing with AC column should be used.

The remediation of two contaminated soils in the Tyne and Wear Metropolitan district was examined. These were a sediment dredged from the river bed at Dunston Coal Staiths on the River Tyne (downstream from Derwenthaugh coke work site) and coke work-contaminated soil from the Derwenthaugh site, Blaydon, Nr. Newcastle-upon-Tyne. The river Tyne dredgings were of a very fine material (70% silt; 24% clay) with high water retention capacity. Levels of (EDTA available) Zn (490mg/kg), total Cd (7.5mg/kg) and total Pb (510mg/kg) were above the Department of Environment's (1987) threshold values for soil contaminants. Barley (Hordeuin vulgare L. cv Kym) sown in the drcdgings in ten outdoor plots (Irn x 0.5m), grew very poorly (yield = 2.4g dry wt. /plant, compared with that on an uncontaminatedc. ontrol soil (7.4g dry wt./ plant). The barley exhibited all the classic signs of metal phytotoxicity despite the addition of fcrtiliscr and organic waste (straw and spent mushroom compost). When lime was added to raise the pH of the dredgings in the plots to over pH 7.1, the growth rate and the yield of barley improved significantly (yield = 6.8g dry wt. /plant). Levels of available Zn, Cd, Pb and Cu in the limed dredgings were now lower than in the unlimed dredgings. Copper and zinc levels in leaves of barley raised on the limed material were lower than levels in barley grown on unlimed dredgings. There was no significant difference in yield or growth rate between the different plots of dredgings in which organic supplementation parameters were varied. In conclusion, pH was the dominant factor in the remediation of the heavy metal phytotoxicity in the dredged material. Gas chromatography/mass spectrophotometry analysis showed the principal contaminants of the coke works soil to be organic. The soil was heavily contaminated with coal tars (19.0%) consisting of a complex mixture of aliphatic, polycyclic and aromatic compounds including phenols (160mg/kg). Viable counts of the soil microflora, on selective media, showed the presence of bacteria capable of degrading phenol and several of its alkylated homologues and thiocyanate, which was converted to ammonia and used as aN source. The coke works soil was treated on a laboratory scale using microbially based clean-up methods. Soil was incubated in glass jars under laboratory conditions. Nu trients (yeast extract) and microbial biomass (a mixed culture, previously isolated and enriched by growth on cresol and thiocyanate, but capable of oxidising a wide range of alkylated phenols), were inoculated into the contaminated soil. The addition of such biomass (106 organisms /g soil) led to a marked improvement in the rate of phenolic degradation in the soil (26% loss in'22 weeks, compared with 9% in the untreated control. ). Degradation rates decreased after 14 days but a repeated application of biomass (106 organisms/g soil) caused further phenolic loss (47% total loss). Cresol (100mg/kg) subsequently added to the bacterial ly-amended soil disappeared within 7 days, showing that the biomass amendment was still biochemically very active. These findings demonstrate the importance and the effectiveness of two different treatment methods in the rcmediation of contaminated soil.