A biological nutrient removal (BNR) activated sludge (AS) scheme incorporating external nitrification in a fixed media system is evaluated. A laboratory scale investigation of the scheme indicates that it holds considerable potential for BNRAS system intensification through major reduction in sludge age and oxygen demand and significant improvement in sludge settleability. Because the BNRAS sys...

In this investigation, the effects of commercial enzyme preparation containing alpha amylase and neutral protease on hydrolysis of excess sludge and the kinetic analysis of hydrolysis process were evaluated. The results indicated that amylase treatment displayed higher hydrolysis efficiency than that of protease. VSS reduction greatly increased to 39.70% for protease and 54.24% for amylase at t...

Digested sludge (DS) is a waste product of anaerobic digestion that produced during the biodegradation excess sludge. It cannot be used as substrate for further biogas production owing to its recalcitrant nature. In present study, we heat treatment technique convert DABYS microflora (DABYS = digested sludge-assimilating and biogas-yielding soil microflora), which degraded DS methane gas, could ...

By modification of the operational conditions of batch reactors, a municipal wastewater treatment plant was upgraded from activated sludge to aerobic granular sludge (AGS) technology. After upgrading, the volume of the biological reactors was reduced by 30%, but the quality of the effluent substantially improved. The concentration of biomass in the reactors increased twofold; the average biomas...

Microbial processes have been extensively used in engineered systems, esp. wastewater treatment, in situ bioremediation and most recently for biofuel production. While excess biomass may be desirable in some processes, it is detrimental to other systems including Activated Sludge Process (ASP), biofilters and subsurface bioremediation schemes, where uncontrolled microbial growth leads to increa...

A survey was conducted of the wastewater treatment systems and related sludge handling practices on the island of Yap, in the Federated States of Micronesia, to assist in identifying areas where further work would be merited to improve on effectiveness and sustainability. A detailed inventory was made of communal septic tanks as found at health centers and schools. Though most of these septic t...

INTRODUCTION Under normal conditions in activated sludge, bacteria occur singly, in small chains or clumps. Under adverse conditions however, bacteria that grow in filaments begin to form longer chains called filamentous bacteria or “filaments”. Filaments can dominate in the wastewater treatment system under a variety of conditions. These conditions are usually less favorable for the floc-formi...

The aim of this paper is to synthesize and analyze information on how the process of granulation is affected by environmental and operational conditions in the reactor. Various factors affecting granulation process as gleaned from the literature are organic loading rate (OLR), upflow velocity (Vup), sludge volume index (SVI), specific methenogenic activity (SMA), VSS/SS ratio, liquid in flow ra...

The purpose of this study was to investigate the photocatalytic oxidation of a reactive azo dye and determine the improvement in the biodegradability when photocatalytic oxidation was used as a pretreatment step prior to biological treatment. The results obtained from the experiments adding H2O2/TiO2 show that the highest decolorisation rate is provided by the combination of (UV+TiO2+H2O2). The...