Two-stage soil infiltration treatment system for treating ammonium wastewaters of low COD/TN ratios

Soil infiltration treatment (SIT) is ineffective to treat ammonium wastewaters of total nitrogen (TN) > 100 mg l−1. This study applied a novel two-stage SIT process for effective TN removal from wastewaters of TN > 100 mg l−1 and of chemical oxygen demand (COD)/TN ratio of 3.2–8.6. The wastewater was first fed into the soil column (stage 1) at hydraulic loading rate (HLR) of 0.06 m3 m−2 d−1 for COD removal and total phosphorus (TP) immobilization. Then the effluent from stage 1 was fed individually into four soil columns (stage 2) at 0.02 m3 m−2 d−1 of HLR with different proportions of raw wastewater as additional carbon source. Over the one-year field test, balanced nitrification and denitrification in the two-stage SIT revealed excellent TN removal (>90%) from the tested wastewaters

Identification of inorganic and organic species of phosphorus and its bio-availability in nitrifying aerobic granular sludge

Phosphorus (P) recovery from sewage sludge is necessary for a sustainable development of the environment and thus the society due to gradual depletion of non-renewable P resources. Aerobic granular sludge is a promising biotechnology for wastewater treatment, which could achieve P-rich granules during simultaneous nitrification and denitrification processes. This study aimed to disclose the changes in inorganic and organic P species and their correlation with P mobility and bio-availability in aerobic granules. Two identical square reactors were used to cultivate aerobic granules, which were operated for 120 days with influent ammonia nitrogen (NH4–N) of 100 mg/L before day 60 and then increased to 200 mg/L during the subsequent 60 days (chemical oxygen demand (COD) was kept constant at 600 mg/L). The aerobic granules exhibited excellent COD removal and nitrification efficiency. Results showed that inorganic P (IP) was about 61.4–67.7% of total P (TP) and non-apatite inorganic P (NAIP) occupied 61.9–70.2% of IP in the granules. The enrichment amount of NAIP and apatite P (AP) in the granules had strongly positive relationship with the contents of metal ions, i.e. Fe and Ca, respectively accumulated in the granules. X-ray diffraction (XRD) analysis and solution index calculation demonstrated that hydroxyapatite (Ca5(PO4)3(OH)) and iron phosphate (Fe7(PO4)6) were the major P minerals in the granules. Organic P (OP) content maintained around 7.5 mg per gram of biomass in the aerobic granules during the 120 days\u27 operation. Monoester phosphate (21.8% of TP in extract), diester phosphate (1.8%) and phosphonate (0.1%) were identified as OP species by Phosphorus-31 nuclear magnetic resonance (31P NMR). The proportion of NAIP + OP to TP was about 80% in the granules, implying high potentially mobile and bio-available P was stored in the nitrifying aerobic granules. The present results provide a new insight into the characteristics of P species in aerobic granules, which could be helpful for developing P removal and recovery techniques through biological wastewater treatment

Feasibility study on the utilization of sludge as building and construction materials

To investigate the feasibility of using sludge and sludge ash as building and construction related materials as an alternative means of sludge disposal.RP 6/8

Treatment of electroplating wastes

The electroplating industry has been playing a momentous role in the development and growth of engineering industries. Wastewater from the electroplating process contains high concentration of heavy metals, are harmful to aquatic life in the receiving waters. Physical - chemical method is commonly used for the treatment of electroplating wastes. The installation costs of treatment plants are 7% and 15% of the total capital invest­ments for the small and large scale plants respectively. The unit treatment costs for electroplating wastes are US$1.46/m 3 and US$0.33/m3 of wastewater treated for small and large plants respectively

Development of nitrifying biofilm for wastewater treatment

With increasing demands on water quality, advanced and cost effective techniques for nitrogen removal fiom wastewater become more and more important and it is believed that biological nitrification-denitrification is an economical method for nitrogen removal. Nitrifying biofilm is such an effective system for nitrogen removal. Thus, this study focused on the growth kinetics of nitrifying biofilm and nitrite build-up in nitrifying biofilm reactor

Biological treatment of high strength wastewaters using attached biomass films

The purpose of the study was to investigate aspects of the use of the Rotating Biological Contactor (RBC) to treat high strength wastewater in a tropical climate. Total organic carbon (TOC), BOD and COD were used as analytical parameters to determine the efficiency of treatment of the wastewater. Also in this study, the fractional removal efficiency and applied - removed loading relationships of the system were compared with predictions from other models.RG 20/9

Anaerobic digestion of strong wastes

This study examines the significance of media specific surface, porosity, pore size, and surface texture on treatment performance of the laboratory scale anaerobic packet-bed system.RG 51/9

Anaerobic digestion of strong organic waste

This study investigated anaerobic granulation process in upflow anaerobic granulation sludge (UASB) reactor.RGM 9/9

Bioaugmentation with a thermophilic inoculum for enhanced bioconversion of sewage sludge and food waste into fertilizer

Two indigenous thermophilic bacterial isolates, identified to be Bacillus stearothermophilus strain SD13 and Bacillus coagulans strain FW04 by partial 16S rRNA gene sequencing, were used to prepare an inoculum in order to bioaugment the bioconversion process from sewage sludge and food waste into fertilizer. Prior to the bioconversion process, a preliminary biodegradability test was performed by inoculating the mixed culture of these two isolates into a 2% sewage sludge and 2% food waste slurry medium and subsequently incubating at 60?C for 10 days. The results showed that the inoculum was effective in degrading sewage sludge and food waste, as indicated by the significantly higher levels of total solids weight loss, volatile solids reduction, CO2 evolution and the increase of pH in comparison with the control in which no inoculum was added

Cultivation of aerobic granules in a bubble column and an airlift reactor with divided draft tubes at low aeration rate

A bubble column and a novel airlift reactor with divided draft tubes were used for the cultivation of aerobic granules at the superficial air velocity of 1.2 cm s?1. It was found that profiles of biomass concentration, average particle size and SVI of biomass showed the same changing trends during the first 40-day operation in the bubble column and the airlift reactor. After 60-day operation, the biomass concentration, average particle size, and SVI of biomass reached 4.5 g l?1, 1300 ?m and 30 ml g?1, respectively, and then maintained at these values during the next 3-month operation in airlift reactor. However, morphology of granular sludge in bubble column changed at day of 50 and then disintegrated into bioflocs at day of 67 when biomass concentration reached to 8.0 g l?1, which led to the great increase of SVI of biomass and the wash-out of lots of biomass from reactor. Clear and regular granules were seen again at day of 75 and granules gradually grew to bigger sizes. But the system deterioration happened again when biomass in bubble column increased to about 8.0 g l?1. It was found that DO concentration in feast period was about 35–40% with biomass concentration of 8.0 g l?1 in bubble column while DO concentration was above 60% with biomass concentration of 4.5 g l?1 in airlift reactor. Thus, it was thought that lower oxygen concentration due to higher biomass concentration was mainly the reason of unstable operation of aerobic granules in bubble column at superficial air velocity of 1.2 cm s?1