A feasibility study of a combined anaerobic-aerobic wastewater treatment system

Abstract

A bench s c a l e combined a n a e r o b i c - a e r o b i c r e a c t o r model was s e t - u p and o p e r a t e d between 21°C and 23*C t o t r e a t s i m u l a t ed w a s t e w a t e r . The main o b j e c t i v e b e i n g t o o b t a i n s i m u l t a n e o us r e m o v a l of n i t r o g e n and c a r b o n from t h e s i n g l e r e a c t o r . The F e a s i b i l i t y of a combined s y s t e m was d e t e r m i n e d by f i r s t d e s i g n i n g such a s y s t e m and t h e n by l o a d i n g t h e s y s t e m w i t h s e t c o n c e n t r a t i o n s o f COD and TKN. The system p e r f o r m e d m o d e r a t e l y w i t h t h e removal of c a r b o n and n i t r o g e n a t 9 2 % and 65% r e s p e c t i v e l y . To improve t he system, m o d i f i c a t i o n s s h o u l d be made t o t h e a e r o b i c l a y e r t o e n s u r e t h a t t h e a c t i v a t e d s l u d g e does n o t s e t t l e t o t h e s i d e s . The c l a r i f i e r s h o u l d a l s o have v e r t i c a l w a l l s and t h e p i p e s i ze o f t h e s y s t e m s h o u l d be chosen t o m a x i m i z e t h e f l o w r a t e . The s t u d y o f s u c h a combined r e a c t o r s h o u l d commence much e a r l i e r so t h a t t h e s y s t e m can s t a b i l i z e and t h e a n a e r o b ic s l u d g e can grow t o a s i z e t h a t w i l l not h i n d e r t h e o v e r a l l p e r f o r m a n c e.