IMPROVING WATER QUALITY AND ENVIRONMENTAL SUSTAINABILlTY BY THE TREATMENT OF LANDFILL LEACHATE WITH ADVANCED OXIDATION AND CONSTRUCTED WETLAND SYSTEMS

Landfill leachate is a potentially toxic and long-lasting waste water for which on-site treatment is increasingly recognised as being necessary. Many forms of leachate treatment systems have been proposed, tria lied and installed for purifying leachate. However most of these treatment systems create by-products such as solid sludge or gas which may need further treatment. They may not also last as long as the leachate continues to be discharged. The objective of this study is to evaluate the potential for two treatment systems which create the minimum of by-products to work in combination to treat leachate. These systems are Reed-Beds or Constructed Wetlands which are by their nature sustainable and Advanced Electrochemical Oxidation (AEOX) which is a recently developed treatment process. The evaluation was conducted by taking leachate samples before and after a reed-bed system actually used on a landfill site and then paSSing these samples through the AEOX process. The AEOX process needed the addition of 5 mg r1 of salt to the leachate to achieve an efficient conductivity, and this had the effect of reducing an already low COO to zero and significantly reducing the level of TSS. It is normal practice for landfill operators to make decisions on capital investment based on the monetary savings a new leachate treatment process will make, as long as the process also fulfils the requirements of Best Available Technology. The Mogden Formula, used by UK sewage undertakers to charge industrial effluent dischargers for effluent disposal is a useful tool for calculating these savings based on the reduction of chemical oxygen demand (COD) and total suspended solids (TSS). The experiment proved that monetary savings were possible but difficult to calculate accurately based on the experimental results. The reduction of other parameters such as ammoniacal-nitrogen and phosphorous were also evaluated for CW, but not for AEOX as the addition of salt interfered with the assessment methods used. Although these are not charged components on the Mogden Formula, they are still Significant in assessing sustainability, and further work will be needed to establish the effectiveness of AEOX in reducing them.Faculty of Scienc