Abstract
Biofilm slime layer is one of the advanced biological treatment technologies for industrial and municipal wastewater treatment with the capacity to reuse of treated water for agricultural purposes. Bacterial, fungal and algal biofilm slime layer were grown on the interior surfaces of polyethylene pellet (carrier) and suspended in municipal wastewater for organic pollutants removal. Bacterial species (Pseudomonas aeruginosa, Bacillus megaterium, Sphingobacterium thalpophilum), fungal species (Penicillium citrinum, Aspergillus niger, Trichoderma harzianum) and algal species (Nostoc linckia, Scendesmus dimorphus) were used separately for biofilm slime layer growth under controlled laboratory conditions (pH, temperature, and aeration). Bacterial biofilm layer thickness was measured and recorded 9, 6 and 5 mm respectively as compared with 3mm for control group through the retention time of 16 day. Bacterial P. aeruginosa biofilm slime layer showed an efficiency for COD, TOC, NO3 and PO4 removal after 24 hour of 75%, 65%, 69% and56% respectively while the removal rates of the same factors using the fungal biofilm layer of P. citrinum was 83%, 78%, 53% and 60% after 48 hour respectively. The algal biofilm reactor with S. dimorphus showed the highest percentage removal rate of total nitrogen 93% as compared to control group 87% after 72 hours of treatment due to the biofilm slime thickness of S. dimorphus 7.5mm as compared to the thickness of the N. linckia slime layer 5.3mm. Mixture of microbial species biofilm layer was used for wastewater treatment through 18 and 24 hours, using aerobic and anoxia. The mixture of microbial species biofilm layer showed removal rates for TOC, COD, and TN of 90%, 83%, and 59% respectively in an aerobic condition, while the removal rates were 66%, 52%, and 84% in an anoxic condition. From the above results, one concludes that controlling the biofilm slim layer is a promising technology for municipal wastewater treatment, as long as it is used under the suitable conditions.
Highlights
Biofilm layer is defined as the dense aggregates of surface-adherent microorganisms which embedded in an extra polysaccharide matrix or substance (EPS) [1]
The objective of this study is to evaluate the environmental factors removal rates of (COD, BOD5, NO3 and PO4) by applying a lab-scale moving bed bacterial and fungal biofilm reactor (MBBR) system filled with biofilm carriers,the biofilm consist of different isolates of microorganism with the changing of environment conditions in wastewater treatment
Table (2) shows the removal rate of TOC, COD and nutrients in wastewater by bacterial biofilm after 48 hours of treatment, which biofilm P. aeroginosa was recorded a remarkable increase in the removal rate of COD, TOC, nitrate and phosphate as follows 78%, 84%, 73% and 87% due to the high density and thickness of biofilm P. aeroginosa 9.5 mm comparing with 6.3mm, 4.1mm and 3.1 for B. megaterium, S. thalpophilum and control after 48 hr. of treatment respectively
Summary
Biofilm layer is defined as the dense aggregates of surface-adherent microorganisms (mostly bacteria) which embedded in an extra polysaccharide matrix or substance (EPS) [1]. The objective of this study is to evaluate the environmental factors removal rates of (COD, BOD5, NO3 and PO4) by applying a lab-scale MBBR system filled with biofilm carriers (pellets),the biofilm consist of different isolates of microorganism (bacteria, fungi and algae) with the changing of environment conditions in wastewater treatment. 2. Fungi: The fungal species Penicillium citrinum, Trichoderma harzianum, Aspergillus niger were isolated from sewage water, were cultured on the various media (PDA and Corn meal agar). Fungi: The fungal species Penicillium citrinum, Trichoderma harzianum, Aspergillus niger were isolated from sewage water, were cultured on the various media (PDA and Corn meal agar) These fungi identified from standard morphological characteristics [9,10] 3. The retention time was considered one of the essential factors in the treatment due to their allowing for the bacteria to grow and reproduction [21]
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