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Integrated treatment of landfill leachates under moderate and cold temperaturesстатья
- Авторы: Kalyuzhnyi S.V., Gladchenko M.A.
- Сборник: Proc. Workshop on Sustainable landfill management
- Год издания: 2003
- Место издания: Chennai, India
- Первая страница: 165
- Последняя страница: 172
- Аннотация: The total annual production of municipal solid wastes in Russia accounts for 37.5 mln. tons from which more than 96% are currently disposed of via landfilling. As a result of microbial activity within a landfill, compression and water flows, a leachate containing a wide variety of intermediate organic degradation products and inorganic contaminants are produced. Since the main concerns in landfill leachates are usually high organic, nitrogen and heavy metals (HM) contamination, the primary objective of this paper was to develop an efficient lab scale technology for removal of these pollutants. As a first step, the UASB reactor was applied for the elimination of the major part of biodegradable COD and concomitant precipitation of HM in the form of insoluble sulphides/hydroxides inside the sludge bed. In a subsequent step, the biofilter operating in alternative aerobic-anoxic regime was used for the removal of remaining BOD and nitrogen. Both steps were investigated at submesophilic (203 oC) and psychrophilic (101 oC) conditions to evaluate a possibility of direct (without heating) treatment in Russian climatic conditions. UASB treatment. During treatment of diluted RL, a step-wise decrease of hydraulic retention time (HRT) to values around 7-8 h (organic loading rates (OLR) were 4.7-4.2 g COD/l/day) led to total COD removals of 81 and 47% (on the average) for submesophilic and psychrophilic regimes, respectively. A little bit more inferior removal of total COD (71%, on the average) was observed for submesophilic treatment of concentrated RL (average HRT – 1.2 days, average OLR - 8.5 g COD/l/day) though even such exhaustion of biodegradable COD might create problems for subsequent biological nitrogen removal (see below). In turn, optimised psychrophilic treatment of concentrated RL ensured an average total COD removal of 58% (average HRT - 2.4 days, average OLR - 4.2 g COD/l/day) giving effluents more balanced with regard to COD/N ratio. Both anaerobic regimes used for both types of RL were quite efficient for elimination of HM – concentrations of Zn, Cu, Pb, Cd were below Russian limits for drinking water. Biofilter performance. Generally, aerobic-anoxic post-treatment of submesophilic anaerobic effluents revealed some problems in total nitrogen removal due to COD deficiency to fulfil denitrification requirements. The most pronounced COD/N misbalance was observed for anaerobic effluents originated from concentrated RL – their processing via biofilter frequently resulted in elevated effluent nitrate concentrations (> 100 mg N/l). On the contrary, the application of aerobic/anoxic biofilter as a sole polishing step (under both temperature regimes) for all psychrophilic anaerobic effluents was quite successful with regard to elimination of biodegradable COD (~ 100%) and total nitrogen (> 91%) approaching to the current standards for direct discharge of treated wastewater
- Добавил в систему: Гладченко Марина Анатольевна