Treatment of municipal wastewater using a contact oxidation filtration separation integrated bioreactor

Assessment and optimization of the use of a novel natural coagulant (Guazuma ulmifolia) for dairy wastewater treatment

A feasible, novel, and natural coagulant extracted from G. ulmifolia stem bark was characterized and used in experiments of coagulation/dissolved air flotation (C/DAF) to treat synthetic dairy wastewater (SDW). The performance of G. ulmifolia to remove turbidity, chemical oxygen demand (COD), and UV₂₅₄ was evaluated by using response surface methodology (Doehlert matrix). G. ulmifolia dosage and pH were evaluated and optimized in the C/DAF process and its characterization was performed by Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and also zeta potential. Results showed that G. ulmifolia stem bark is composed of large quantities of condensed tannins represented by the groups C=C-C and CO of pyran (flavonoid C-rings), which serve as bridges during coagulation. Moreover, the presence of porous cavities in surface of G. ulmifolia, shown by SEM, indicated capacity for adsorption. G. ulmifolia dosage and pH were significant (p ≤ 0.05) for pollutant removal from the SDW. Jar test results revealed that 95.8% of turbidity, 76.0% of COD, 81.2% of BOD, and 85.6% of UV₂₅₄ were removed from SDW by using G. ulmifolia stem bark at a dose of 775.8 mg L^-1 and pH 5.00. Finally, our results showed promising use of G. ulmifolia as a coagulating agent due to its novelty, efficiency, low-cost, and eco-friendly properties as an alternative for the treatment of dairy wastewaters.

Determination of optimum conditions for dairy wastewater treatment in UAASB reactor for removal of nutrients

In this study, the granular sludge was generated for simultaneous nitrification, denitrification and phosphorus removal (SNDPR) and studied on a laboratory scale. Analyzing the nutrients removal percentages from wastewater were scrutinized by using an optimization of the variables, i.e., COD:N:P ratio, OLR, aeration time, MLSS, F:M and HRT. These 6 interrelated parameters were evaluated as the process response. Microscopic observations of the performance of the SNDPR process revealed that the granules included Bacillus sp. in the bacterial community. According to these results, the UAASB system produced an effluent that lends dairy wastewater suitable for land irrigation and that this an attractive process of using granular sludge is appropriate for achieving carbon, nitrogen and phosphorus removal from nutrient-rich wastewater by a biological method.

Wastewater treatment using a modified A2O process based on fiber polypropylene media

The removal rates of organics and nutrients in municipal wastewater were examined using a laboratory-scale Anaerobic/Anoxic/Oxic (A2O) process modified with fiber polypropylene media at different operational conditions. The system demonstrated excellent performance with the removal rates of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorous (TP) ranging from 91% to 98%, from 48% to 63%, and from 56% to 71%, respectively. Our system was superior to those previously reported based on more complex biofilm reactors, particularly from an economic point of view. For our system, a considerable reduction of COD (55%-68%) occurred even in the anaerobic reactor. The removal rates of COD and nutrients exhibited a slight decreasing trend with a higher organic loading rate (OLR) (0.5 to 2.2 kg COD m(-3) day(-1)) or with a shorter hydraulic retention time (HRT). The results may be attributed to the competition between nitrifying and heterotrophic bacteria and/or the insufficient time for biological uptake. It is expected that applying fiber polypropylene media to a conventional A2O process may significantly enhance the treatment efficacy of organics and nutrients as a cost-effective strategy.