COD fractionation and biological treatability of mixed industrial wastewaters

Assessment and modeling of effluent quality, economic benefits, and greenhouse gas reduction for receiving brewery wastewater on A2O by GPS-X

Recently, breweries have been allowed to discharge brewery wastewater (BWW) to the sewage pipe network to alleviate the shortage of carbon sources of municipal wastewater treatment plants (MWTPs) under the premise of signing a contract with MWTPs in some countries. This study aims to provide a model-based method for MWTPs to evaluate the threshold, the effluent risk, the economic benefits, and the potential greenhouse gas (GHG) emissions reduction of receiving BWW. In this research, a simulation model of an anaerobic-anoxic-oxic process (A²O) receiving BWW was established based on the data of a real MWTP and brewery using GPS-X. The sensitivity factors of 189 parameters were analyzed, and several sensitive parameters were calibrated stably and dynamically. By analyzing the errors and standardized residuals, the calibrated model was proved to be high-quality and reliable. In the next phase, the impact of receiving BWW on the A²O was evaluated in terms of effluent quality, economic benefits, and GHG emissions reduction. The results showed that receiving a certain amount of BWW can effectively reduce the carbon source cost and GHG emissions for the MWTP compared with adding methanol. Though the chemical oxygen demand (COD), biochemical oxygen demand in five days (BOD₅), and total nitrogen (TN) in the effluent increased in various degrees, the effluent quality still met the discharge standard implemented by the MWTP. The study can also facilitate the modeling work for many researchers and promote more kinds of food production wastewater to be treated equally.

Determination and evaluation of kinetic parameters of activated sludge biomass from a sludge reduction system treating real sewage by respirometry testing

Oxic-settling-anoxic (OSA) process is one of the promising variants that produces lower amounts of sludge and has been applied to aerobic and nutrient removal systems. The only consequence on this modification is that supplementary research is advisable to fully understand the mechanism, which eventually leads to the development of a more realistic model. This study evaluated the characteristics of an OSA process as a sludge reduction system by calibration of kinetic coefficients of ASM1 model with some modifications. A series of respirometric tests were designed for the assessment of microbial kinetics and for further clarification of sludge reduction mechanism. The calibration results depicted that the decay rate is the most variable kinetic parameter depending on the system configuration. It was determined that this kinetic coefficient increased significantly after the system was modified into OSA configuration while other model parameters were almost kept constant. This may be referred to a change either in the microbial population or in the metabolism of the community. The active biomass ratio in the CAS reactor was found to be around 75%, while it was almost 2 times lower in the side-stream reactor. All results led to a conclusion that OSA process is encouraging endogenous decay and consequently lowers biomass viability in the reactor and achieves excess sludge reduction in the system. All experimental results confirmed that side-stream reactor accelerates decay rate of the community and causes the introduction of sludge with low viability to the main reactor.

Reduction of adsorbed dyes content in the discharged sludge coming from an industrial textile wastewater treatment plant using aerobic activated sludge process

Dye mass balance study at full-scale industrial textile wastewater (ITW) treatment plant showed that 1.5 ton of excess waste sludge, containing 304.5 Kg of dyes, are daily produced and discharged in landfills. Therefore, this by-product of activated sludge process (ASP) presents a serious environmental problem. In this work, a laboratory and pilot scale investigations were carried out to optimize aerobic biodegradation efficiency to reduce the amount of residual adsorbed dye that will be found in the waste sludge. The resistance of acclimated biomass to the toxicity of ITW was studied in 2.5 L batch reactors using different dye to biomass (D/B) ratios of 0.102, 0.25 and 0.72 g COD_S/g VSS. Results of respirometric analyses showed that acclimated activated sludge (AS) biomass is able to treat ITW at high D/B ratio of 0.72 g COD_S/g VSS. Moreover, biodegradation kinetic study using Monod law showed that COD and color removal were better for the highest D/B ratio. The half saturation coefficient of heterotrophs for indigo dye (K_Sind) of 20.01 g/m³ showed high affinity between biomass and dye molecules. Optimization of the process at pilot-scale with different hydraulic retention time (HRT) of 2-5 days, and different sludge recycling rates (SRR) of 220-680 m³/d, showed that high HRT of 5 days and a SRR of 0.22 allowed the best dye biodegradation efficiency (95%). Application of the best conditions at full-scale reduced significantly (89%) the amount of the discharged dyes from 304.5 Kg/d to 33 Kg/d. Results were numerically validated using a mathematical model based on the activated sludge model 1 (ASM1).

A critical review on characterization strategies of organic matter for wastewater and water treatment processes

The presence of organic matter (OM) in raw wastewater, treated wastewater effluents, and natural water samples has been known to cause many problems in wastewater treatment and water reclamation processes, such as treatability, membrane fouling, and the formation of potentially toxic by-products during wastewater treatment. This paper summarizes the current knowledge on the methods for characterization and quantification of OM in water samples in relation to wastewater and water treatment processes including: (i) characterization based on the biodegradability; (ii) characterization based on particle size distribution; (iii) fractionation based on the hydrophilic/hydrophobic properties; (iv) characterization based on the molecular weight (MW) size distribution; and (v) characterization based on fluorescence excitation emission matrix. In addition, the advantages, disadvantages and applications of these methods are discussed in detail. The establishment of correlations among biodegradability, hydrophobic/hydrophilic fractions, MW size distribution of OM, membrane fouling and formation of toxic by-products potential is highly recommended for further studies.