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Total nitrogen (TN) removal by sewage treatment required the development of nitrifying and denitrifying activities; however, these metabolite activities can produce and emit nitrous oxide (N 2 O), one of the greenhouse gases (GHG). With the expansion of sewage treatment in the world, compact systems such as moving bed biofilm reactor (MBBR) may be promising, mainly in more populated cities. However, little is known about N 2 O emission by the MBBR. This work investigated the N-NH x and TN removal, N 2 O production and emission and nitrogen mass balance in a MBBR under organic load and airflow variation. The highest TN removal (47%) was observed under higher load and higher aeration rate. Meanwhile, the MBBR under lower load and lower airflow had the lowest efficiency of TN and N-NH x removal probably due to a lower nitrifying activity. The N 2 O emission factors were lower than 1.6% (value estimated by the IPCC for sewage aerobic treatment systems). In addition, in the essay with higher load and lower airflow, half of removed TN was released by settled sludge and there is little research about this subject. Therefore, the MBBR showed to be a promising process for nitrogen removal with little emission of N 2 O even under different operational conditions that normally can occur in sanitary sewage system in cities around the world. • Importance of dissolved oxygen to N-NHx removal and nitrification activity in MBBR. • Low N 2 O emission factor in MBBR even under high aeration rate condition. • High removal of nitrogen in MBBR by settling sludge under low airflow condition. • High removal of nitrogen in MBBR by atmospheric air (as N 2) under high airflow condition. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Aeration pattern is of prior importance compared to aeration intensity during granulation. • Gas distributor characteristics greatly influence on prevailing aeration pattern. • Gas holdup is an easy-to-measure controlling parameter for scale-up of granular reactors. Abstract This study investigates the influence of aeration pattern and gas bubble distribution on aerobic granulation in pilot bubble columns and advances the understanding on crucial factors to be considered during scale-up. Experiments were conducted in a pilot scale bubble column of 22-L capacity. A laboratory-scale bubble column of 5-L capacity, which could achieve granulation in a short time, was used as the control reactor. The pilot reactor was operated with optimal operational conditions evaluated for the control reactor, but the granulation was initially inhibited; improper aeration pattern was found as the most significant factor in precluding granulation. Aerobic granulation in the pilot-scale reactor was achieved upon modifying the gas distributor design. The effect of gas distributor characteristics (i.e. , pore size, free area φ , and relative surface area of the gas distributor to the cross-section of the column R) on the aeration pattern has been thoroughly discussed. A scale-up ratio (S) for the gas distributor has been proposed. Reliability of aeration intensity in terms of superficial air velocity u sg , which has been commonly used as an indicator of prevailing hydrodynamics and shear stress in lab-scale granular bubble columns, has been discussed; it was demonstrated that u sg could not realistically represent the aforementioned conditions in a larger module. Instead, it was suggested that a greater attention should be paid to bubble size and bubble ascending velocity and thus to the subsequent aeration pattern. Gas holdup has been eventually introduced as a crucial and easy-to-measure controlling parameter for the scale-up of granularreactors. [ABSTRACT FROM AUTHOR]

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The oxidation process using chlorine will also consume Further addition of chlorine will produce a chlorine residual that's directly proportional to the amount of chlorine added beyond the breakpoint. If just a little more chlorine is added, the chloramines are destroyed and breakpoint, the point at which a little more chlorine will begin to produce a free available chlorine residual, has been reached. A water molecule is formed of two atoms of hydrogen and one atom of oxygen bonded by polar covalent bonds. [Extracted from the article]

The paper presents the prospects of using the technology of low-oxygen aerobic wastewater treatment – simultaneous nitrification and denitrification – as energy-efficient solution for construction and reconstruction of wastewater treatment plants for small settlements in the conditions of the Russian Federation. The results of an experiment (the second phase) conducted on a laboratory model of the Oxidation Ditch are described. The paper presents the horizontal model of the Oxidation Ditch that will be used for further experiments. This model differs from previous ones in its hydraulic performance. [ABSTRACT FROM AUTHOR]

The upflow anaerobic sludge blanket (UASB) bioreactor was reviewed in search of a sustainable biotechnology solution for the management of winery wastewater (WWW) accumulation. Aerobic wastewater treatment systems are notorious for heavily exploiting energy and water resources, wasting residual materials, and depending on commercialised chemicals for winery wastewater treatment (WWWT). In comparison, anaerobic digestion (AD) and accelerated anaerobic bioprocesses, such as the UASB bioreactor, holds the potential to save electric kWh (kWh-e), water, sludge waste, and chemical residue generated during WWWT. The successful implementation of the UASB bioreactor at the wineries and wastewater treatment plants (WWTPs) is dependent on the preparedness of the biotechnology to manage the fluctuating discharge of raw WWW and meet the legislative demands for high product quality at a low cost. A rapid analysis approach and post-treatment options are proposed in the literature as a possible aid for inexpensive WWW quality control and hence effective WWW management. The conditions for optimum biogas production and the removal of chemical oxygen demand (COD) in the UASB bioreactor were also reviewed. Optimal COD removal and biogas production for reactors operating under mesophilic bioreactors (30–35 ℃) were observed when OLR and HRT were 6 kg/m3/d and 22 h, respectively, while submesophilic bioreactors (19–21 ℃) required an OLR and HRT of 7 kg/m3/d and 16 h, respectively. [Display omitted] • A review of the treatment of winery wastewater, a by-product in the production on wine. • Treatment of winery wastewater using UASB biotechnologies, addressing substrate, operating temperature and pH. • Resource recovery from UASB with respect to biogas, sludge pellets, and a look at reclamation and recycling. [ABSTRACT FROM AUTHOR]

Development and maintenance of mill- and wastewater treatment system-specific programs aimed at optimizing use of supplemental nutrients for purposes of minimizing residual nutrients in treated effluents have evolved in recent years and are summarized. Suggestions for monitoring of nutrient forms in wastewaters prior to and during biological treatment are presented, as are approaches for determining supplemental nutrient requirements, monitoring biomass characteristics, and achieving minimum nitrogen and phosphorus residuals in treated final effluents while maintaining targeted levels of biological treatment. Aspects of nutrient management relevant to activated sludge (AS) and aerated stabilization basin (ASB) systems are presented, and ASB configurations operated in part to minimize nutrient levels in treated effluents are highlighted. [ABSTRACT FROM AUTHOR]

Highlights: [•] Lab studies at realistic hydrocarbon concentrations, plume dilution and dispersion conditions. [•] Physical dilution and biodegradation of oil at sea is rapid even close to source. [•] Rapid dilution allows bacteria to aerobically biodegrade dispersed oil. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates how to attain effective air stripping of manure with a small amount of chemicals and with no strong bases such as sodium hydroxide (NaOH). Slurry was referred to aerobic biological treatment to increase potential of hydrogen (pH) before stripping, facilitating the removal of ammonia from 8-32% without chemical treatment. The study revealed that buffer capacity reduction of the slurry was because of carbonate and ammonia removal during the stripping cycles.

Abstract: A two stage sequential Fenton''s Pre-oxidation followed by aerobic biological treatment train was used to achieve mineralization of refractory organics and enhance biodegradability of chemical industry integrated wastewater. In the first stage, Fenton''s Pre-oxidation process was used while in the second stage activate diatomaceous earth (DE) activated sludge process (ASP) was used as biochemical treatment process. The parameters influencing the COD removal of the wastewater, reaction time, ferrous ion concentrations and molar ratio hydrogen peroxide to ferrous ion R, the initial pH have been optimized to achieve a COD reduction of 60.2% by single factor analysis method. Meanwhile the biodegradability BOD/COD (B/C) value of wastewater was studied which significant improvement was observed initial wastewater B/C value of 0.143 increased to 0.35. It was beneficial to sequential biological treatment after Fenton''s Pre-oxidation. In the second stage, activate DEASP shows a mild positive effect on COD removal which further increased to 88%. Simultaneously, analysis organism from wastewater and effluent of the two stages by GC/MS. The results showed that: Fenton''s reaction can be considered a suitable pre-treatment which followed by aerobic biological treatment sequence have proved to viable technique for this type of chemical integrated wastewater. [Copyright &y& Elsevier]

Abstract: The effluent from the aerobic treatment of a gasification factory was treated by coagulation process. PAC was used as coagulant, CPAM and decoloration reagent were used as coagulant aid to investigate the optimal dosage of coagulant and coagulant aid. The results indicated that the optimize dosage of PAC was 140mg/L, COD removal rate was 29.1% and the decoloration rate was 60%. The optimal dosage of CPAM was 2mg/L when the PAC dosage was 140mg/L, COD removal rate was 35.7% and decoloration rate was 67.1%. The optimal dosage of decoloration reagent was 4mg/L when the PAC dosage was 140mg/L, COD removal rate was 42.1% and decoloration rate was 77.2%. The reasonable dosage of coagulant and coagulant aid was according to the wastewater quality in the engineering operation. [Copyright &y& Elsevier]

Abstract: Ultrasonic pre-treatment of sludge increases the biodegradability and decomposition efficiency in a sludge digestion process, due to its ability to breakdown complex macro-molecular structure of the floc into a micro-molecular structure. The first part of this study focused on determining the optimum operating condition for ultrasonic pre-treatment, for achieving better destruction efficiency of sludge, while the second part focused on investigating the effect of ultrasonic pre-treatment on the aerobic sludge digestion process efficiency at room temperature and thermophilic condition. The results showed that, 30min of ultrasonic pre-treatment applied at an energy output of 480W, i.e., when the specific energy output was 397kJ/gSS, better cell wall destruction efficiency was achieved. This pre-treatment step also increased the dissolution rate of chemical oxygen demand (COD) up to 44.4%, in comparison to without pre-treated sludge. The addition of ultrasonic pre-treatment greatly reduced the retention time of the thermophilic aerobic digestion process from 15 days to 3 days, for about 55% of VSS removal efficiency. This study demonstrates the usefulness of the ultrasonic pre-treatment step in a sludge digestion process. [Copyright &y& Elsevier]

Abstract: The study on the integrated COD and nitrogen removal from domestic wastewater was carried out in a micro-aerobic granular sludge reactor. The influences of oxygen flux, hydraulic retention time (HRT), biomass concentration and sludge loading were investigated. The reactor showed stable and effective COD removal all through the experiment. Nevertheless, nitrogen removal much depended on the operation mode. Under the optimal condition, i.e. oxygen influx, HRT, MLSS and sludge loading rate (SLR) were 0.20g/L·d, 8h, 11∼16g/L and below 0.10kgCOD/kgMLSS·d, respectively, total nitrogen (TN) removal efficiency achieved 82%, and the concentration of NH4+-N and TN in effluent were 5.5mg/L and 8.2mg/L, respectively. Besides, deteriorated sludge settling and filamentous granules were found as SLR increased to 0.18kgCOD/kgMLSS·d. [Copyright &y& Elsevier]

The article discusses the study which examines the microbially mediated aerobic and anaerobic degradation of acrylamide (AMD) in unlined irrigation canal systems in the U.S. A comprehensive testing and analysis of the concentrations of neurotoxins in carcinogenous AMD uses sediment samples that contained microorganisms that convert AMD into carbon. The study demonstrates that natural microorganisms and bacteria are capable of AMD degradation under aerobic and anaerobic conditions within the freshwater irrigation canal systems similar lotic habitats.

The technology of statically and continuously aerobic fermentation of composting garbage stored in cellar has been widely used for waste treatment. In this study, through establishing a water balancing system, we have systematically studied the effects of water content on this whole fermentation technology. The resulted fermentation from using this technology has the characteristics of being technologically simpler, having faster heat exchange rate, and larger quantity of vapor evaporation. In this study, the fermentation temperature was held at about 65 °C, and water content at 45% - 55%, which helps the decomposition of organic materials and leads to the completion of garbage composting in 40 to 50 d. The water content of ferment from the first aerobic fermentation should be under 35%, which gives high efficiency of automatic mechanical separation (filtration), normally at 90 - 95%, and decreases the volume of garbage at about 50% - 60%. The water content of ferment materials should be controlled at 25% - 30% for second fermentation. This increases the efficiency of mechanical removal of solid materials (broken stones and glass, etc.) and decreases them to 0.8% in the organic materials. The second garbage static state aerobic fermentation can utilize water drained out from the garbage to augment the water supply. Therefore, the resources can be recycled for reutilization and zero wastewater discharge can become true. [ABSTRACT FROM AUTHOR]