Surampalli Rao

Development of anammox process for removal of nitrogen from wastewater in a novel self-sustainable biofilm reactor.

Effluent of an upflow anaerobic sludge blanket reactor was treated in a downflow rope-bed-biofilm-reactor (RBBR) to remove residual organic matter and nitrogen. Nitrogen removal was observed in phase 1 and phase 2 with and without aeration, respectively for 320days each. Organic matter, ammonia and total nitrogen removal efficiencies of 78±2%, 95±1% and 79±11% were obtained in phase 1 and 78±2%, 93±9% and 87±6% in phase 2, respectively. In phase 2, anammox bacteria had a specific anammox activity of 3.35gNm(-2)day(-1). Heme c concentration, sludge characteristics and reaction ratios of dissolved oxygen, alkalinity and pH corroborated contribution of anammox process. Using experimental results kinetic coefficients required for design of RBBR were estimated. Anammox gave more stable performance under varying nitrogen loading and this option is more sustainable for solving problem of nitrogen removal from sewage.

Low efficiency of sewage treatment plants due to unskilled operations in India

Centralized sewage treatment plants may not be a sustainable solution for a developing country such as India. Therefore, we conducted for the first time an integrated assessment of the different technologies currently used for sewage treatment in the state of West Bengal, India. Five decentralized sewage treatment plants and one centralized sewage treatment plant located in different parts of Kolkata were evaluated. We compared influent and effluent water quality, energy consumed, capital and operating costs, and treated wastewater reuse potential. F test was used to validate results on the effect of working days and holidays and seasons on treated water quality. Wastewater management strategy was assessed by performance indicators. Our results show that treatment efficiency was lowest in anaerobic plants not because of faulty technology but due to unskilled operation. Therefore, performance improvement of plants is expected if factors such as monitoring, training of staff, regular and scrupulous desludging, reuse aspects, and rational water tariff are implemented earnestly.

Sludge granulation in an UASB–moving bed biofilm hybrid reactor for efficient organic matter removal and nitrogen removal in biofilm reactor

ABSTRACT A hybrid upflow anaerobic sludge blanket (UASB)–moving bed biofilm (MBB) and rope bed biofilm (RBB) reactor was designed for treatment of sewage. Possibility of enhancing granulation in an UASB reactor using moving media to improve sludge retention was explored while treating low-strength wastewater. The presence of moving media in the top portion of the UASB reactor allowed a high solid retention time even at very short hydraulic retention times and helped in maintaining selection pressure in the sludge bed to promote formation of different sized sludge granules with an average settling velocity of 67 m/h. These granules were also found to contain plenty of extracellular polymeric substance (EPS) such as 58 mg of polysaccharides (PS) per gram of volatile suspended solids (VSS) and protein (PN) content of 37 mg/g VSS. Enriched sludge of nitrogen-removing bacteria forming a porous biofilm on the media in RBB was also observed in a concentration of around 894 g/m2. The nitrogen removing sludge also had a high EPS content of around 22 mg PS/g VSS and 28 mg PN/g VSS. This hybrid UASB-MBB-RBB reactor with enhanced anaerobic granular sludge treating both carbonaceous and nitrogenous matter may be a sustainable solution for decentralized sewage treatment.

Role of Bacillus cereus GS-5 strain on simultaneous nitrogen and phosphorous removal from domestic wastewater in an inventive single unit multi-layer packed bed bioreactor

This work evaluates the performance efficiency of a newly developed single unit packed bed bioreactor for nutrient removal from domestic wastewater. The packing materials, including dolochar, and a mixture of waste organic solid substance, were immobilized with a simultaneous nitrifying, denitrifying and phosphate removing bacterial strain, Bacillus cereus GS-5 and packed in the bioreactor alternatively in multiple layers. The bioreactor was operated continuously for a period of 70 days using both synthetic and real domestic wastewater (NH4+-N 30-100 mg/L, NO3--N 10-100 mg/L, PO43--P 5-20 mg/L and COD 250-1000 mg/L). The innovative single unit bioreactor exhibited simultaneous removal of NH4+-N (87.1-93.1%), NO3--N (69.4-88.4%), PO43--P (84-100%), and even COD (69.8-92.1%), in a remarkable disparity to traditional distinct aerobic-anaerobic treatment systems. This work advocated for a promising and feasible application prospect of the developed single unit packed bed bioreactor in domestic wastewater treatment emphasizing on nutrient removal.