Biological Treatment of Shrimp Aquaculture Wastewater Using a Sequencing Batch Reactor

To improve the water quality in the shrimp aquaculture, a sequencing batch reactor (SBR) has been tested for the treatment of shrimp wastewater. A SBR is a variation of the activated sludge biological treatment process. This process uses multiple steps in the same tank to take the place of multiple tanks in a conventional treatment system. The SBR accomplishes equalization, aeration, and clarification in a timed sequence in a single reactor basin. This is achieved in a simple tank, through sequencing stages, which include fill, react, settle, decant, and idle. A laboratory scale SBR and a pilot scale SBR was successfully operated using shrimp aquaculture wastewater. The wastewater contained high concentration of carbon and nitrogen. By operating the reactor sequentially, viz, aerobic and anoxic modes, nitrification and denitrification were achieved as well as removal of carbon in a laboratory scale SBR. To be specific, the initial chemical oxygen demand (COD) concentration of 1,593 mg/l was reduced to 44 mg/l within 10 days of reactor operation. Ammonia in the sludge was nitrified within 3 days. The denitrification of nitrate was achieved by the anaerobic process and 99% removal of nitrate was observed. Based on the laboratory study, a pilot scale SBR was designed and operated to remove excess nitrogen in the shrimp wastewater. The results mimicked the laboratory scale SBR.     

Uncoupled metabolism stimulated by chemical uncoupler and oxic-settling-anaerobic combined process to reduce excess sludge production

The effects of three uncoupled metabolic systems (conventional activated sludge process with the addition of 3,3′,4′,5-tetrachlorosalicylanilide [TCS], oxic-settling-anaerobic [OSA] process modified by insertion of a sludge-holding tank in the sludge return line, and TCS and OSA combined process) on reducing excess sludge production were studied. Compared with the control conventional activated sludge process, the most effective system was the combined process, which could reduce excess sludge production by 46.90%. The 180-d operation results confirmed that TCS is an effective chemical uncoupler in reducing the sludge yield but that it had an adverse effect on substrate removal capability, effluent nitrogen concentration, and sludge settleability. The OSA process decreased excess sludge production by only 26% but had less adverse effect on effluent quality and could improve sludge settleability. The effluent total phosphorous concentration of the three systems was slightly lower than of the control unit. Microbial populations were monitored by both microscopic and molecular biologic analysis method (polymerase chain reaction [PCR]-denaturing gradient gel electrophoresis [DGGE]). The presence of TCS caused metazoans to disappear and decreased the number and activity of protozoa. PCR amplification of 16S rRNA and sequent DGGE analysis found a shift in the diversity of the predominant species. The results imply that OSA combined with the chemical uncoupler process may effectively reduce excess sludge yield and not affect process performance significantly.     

Effects of trace levels of copper,chromium, and zinc ions on the performance of activated sludge

The effects of copper, chromium, and zinc ions, at trace levels, on the performance of a simulated activated sludge process were investigated. The results of batch adsorption experiments showed that the adsorption of copper, chromium, and zinc ions followed both the Langmuir and Freundlich isotherms. The presence of trace levels of these three metals not only reduced the adsorption rate of organic matters but also the chemical oxygen demand adsorption capacity (CAC) of the activated sludge. Metal ions competed with the organic substrate for adsorption binding sites on the surfaces of activated sludge bioflocs and reduced the CAC. Studies performed in a sequential batch reactor (SBR) showed that the presence of trace levels of heavy metal ions in wastewater affected the SBR performance to different extents depending on the hydraulic retention time (HRT). When the reactors were operated at short HRTs of 2.5 d or less, the presence of trace levels of heavy metal ions reduced substantially the CAC of activated sludge, which, in turn, affected significantly the performance of the SBR. However, under longer HRTs (e.g., 5d), the heavy metal ions in the wastewater reduced the CAC but had not significant effect on the chemical oxygen demand removal efficiency.     

Biodegradability enhancement of textile wastewater by electron beam irradiation

Textile wastewater generally contains various pollutants, which can cause problems during biological treatment. Electron beam radiation technology was applied to enhance the biodegradability of textile wastewater for an activated sludge process. The biodegradability (BOD₅/COD) increased at a 1.0 kGy dose. The biorefractory organic compounds were converted into more easily biodegradable compounds such as organic acids having lower molecular weights. In spite of the short hydraulic retention time (HRT) of the activated sludge process, not only high organic removal efficiencies, but also high microbial activities were achieved. In conclusion, textile wastewater was effectively treated by the combined process of electron beam radiation and an activated sludge process.     

Municipal wastewater treatment by periodic biofilter without excess sludge production

The paper reports the results of an investigation aimed at evaluating the performances of a periodic biofilter (SBBR) for treating municipal wastewater. The investigation was carried out at laboratory scale on real primary effluent coming from a municipal wastewater treatment plant located in Southern Italy. The SBBR was designed for carbon and nitrogen removal through one single stage. The results have shown that even at maximum organic load (i.e., 7 kg COD/m3.d), the COD in the effluent was lower than 60 mg/L. TKN removal efficiencies resulted high (i.e. 90-95%) up to an organic load of 5.7 kg COD/m3.d corresponding to a nitrogen load of 0.8 kg TKN/m3.d. NO3-N concentration in the treated effluent was lesser than 6 mg/L although in the SBBR treatment cycle no anoxic phase was scheduled. This indicated that denitrification extensively took place in the biofilter. The process was characterized by high suspended solids removal (about 90%) and by a negligible sludge production (lower than 0.01 kgVSS/kgCODremoved). In the SBBR, biomass grew as granules and was characterised by different measurements (biomass concentration, cellular protein and biomass density). Biomass density resulted very high, i.e. 200 gTSS/Lbiomass, and this permitted to achieve a biomass concentration such high as 40 gTSS/Lbed. Such biomass concentration did not cause any decrease of biomass metabolic activity as proved by its total protein content (29% of organic matter) and maximum oxygen uptake rate value (i.e. 50 mgO2/gVSS h).     

Treatment options for tannery wastewater II: integrated chemical and biological oxidation

This is the second of two papers each dealing with a specific technological option for replacing the Fenton's reagent with simpler processes for treating industrial wastewater. In particular, the paper reports the results of an investigation aimed to check, at lab scale, the effectiveness of an alternative wastewater treatment combining biological degradation and chemical oxidation with ozone. The treatment was carried out in a lab scale hybrid reactor fed with the biological stage effluent of a plant treating the wastewater of a large tanning district in Central Italy whose residual COD result still higher than the Italian COD Maximum Allowable Concentration (MAC) value (i.e., 160 mgO2/L) The results are very promising, considering that a removal efficiency of 41% (as COD) has been achieved by treating an influent characterized by a COD content fully biorefractory. In addition, the proposed treatment presents the significant advantage of no additional sludge production, as happens with commonly utilized tertiary processes (i.e. Fenton), that is characterized by high chemical sludge production.     

One- and two-stage upflow anaerobic sludge-bed reactor pretreatment of winery wastewater at 4–10°C

The operating performance of a single and two (in series) laboratory upflow anaerobic sludge-bed (UASB) reactors (2.7-L working volume, recycle ratio varied from 1:1 to 1:18) treating diluted wine vinasse was investigated under psychrophilic conditions (4-10 degreesC). For a single UASB reactor seeded with granular sludge, the average organic loading rates (OLRs) applied were 4.7, 3.7, and 1.7 g of chemical oxygen demand (COD)/(L.d) (hydraulic retention times [HRTs] were about 1 d) at 9-11, 6 to 7, and 4 to 5 degreesC, respectively. The average total COD removal for preacidified vinasse wastewater was about 60% for all the temperature regimes tested. For two UASB reactors in series, the average total COD removal for treatment of non-preacidified wastewater exceeded 70% (the average OLRs for a whole system were 2.2, 1.8, and 1.3 g of COD/[L.d] under HRTs of 2 d at 10, 7, and 4 degreesC, respectively). In situ determinations of kinetic sludge characteristics (apparent Vm and Km) revealed the existence of substantial mass transfer limitations for the soluble substrates inside the reactor sludge bed. Therefore, application of higher recycle ratios is essential for enhancement of UASB pretreatment under psychrophilic conditions. The produced anaerobic effluents were shown to be efficiently posttreated aerobically: final effluent COD concentrations were about 0.1 g/L. Successful operation of the UASB reactors at quite low temperatures (4-10 degreesC) opens some perspectives for application of high-rate anaerobic pretreatment at ambient temperatures.     

Fermentative Hydrogen Production from Soybean Protein Processing Wastewater in an Anaerobic Baffled Reactor (ABR) Using Anaerobic Mixed Consortia

Fermentative H(2) production from soybean protein processing wastewater (SPPW) was investigated in a four-compartment anaerobic baffled reactor (ABR) using anaerobic mixed cultures under continuous flow condition in the present study. After being inoculated with aerobic activated sludge and operated at the inoculants of 5.98?gVSS?L(-1), COD of 5000?mg?L(-1), HRT of 16?h and temperature of (35?±?1) °C for 22?days, the ABR achieved stable ethanol-type fermentation. The specific hydrogen production rate of anaerobic activated sludge was 165?LH(2)?kg MLVSS(-1)?day(-1), the substrate conversion rate was 600.83?LH(2)?kg COD(-1)and the COD removal efficiency was 44.73% at the stable operation status. The ABR system exhibited a better stability and higher hydrogen yields than continuous stirring tank reactor under the same operational condition. The experimental data documented the feasibility of substrate degradation along with molecular H(2) generation utilizing SPPW as primary carbon source in the ABR system.     

Anaerobic treatment of low-strength brewery wastewater in expanded granular sludge bed reactor

Anaerobic treatment of low-strength brewery wastewater, with influent total chemical oxygen demand (COD) (CODin) concentrations ranging from 550 to 825 mg/L, was investigated in a pilot-scale 225.5-L expanded granular sludge bed (EGSB) reactor. In an experiment in which the temperature was lowered stepwise from 30 to 12 degrees C, the COD removal efficiency decreased from 73 to 35%, at organic loading rates (OLR) of 11-16.5 g COD/L/d. The applied hydraulic retention time (HRT) and liquid upflow velocity (Vup) were 1.2 h and 5.8 m/h, respectively. Under these conditions, the acidified fraction of the CODin varied from 45 to 90%. In addition to the expected drop in reactor performance, problems with sludge retention were also observed. In a subsequent experiment set at 20 degrees C, COD removal efficiencies exceeding 80% were obtained at an OLR up to 12.6 g COD/L/d, with CODin between 630 and 715 mg/L. The values of HRT and Vup applied were 2.1-1.2 h, and 4.4-7.2 m/h, respectively. The acidified fraction of the CODin was above 90%, but sludge washout was not significant. These results indicate that the EGSB potentials can be further explored for the anaerobic treatment of low-strength brewery wastewater, even at lower temperatures.     

Combined biologic (anaerobic-aerobic) and chemical treatment of starch industry wastewater

A combined biologic and chemical treatment of high-strength (total chemical oxygen demand [CODtot] up to 20 g/L), strong nitrogenous (total N up to 1 g/L), and phosphoric (total P up to 0.4 g/L) starch industry wastewater was investigated at laboratory-scale level. As a principal step for COD elimination, upflow anaerobic sludge bed reactor performance was investigated at 30 degrees C. Under hydraulic retention times (HRTs) of about 1 d, when the organic loading rates were higher than 15 g of COD/(L.d), the CODtot removal varied between 77 and 93%, giving effluents with a COD/N ratio of 4-5:1, approaching the requirements of subsequent denitrification. The activated sludge reactor operating in aerobic-anoxic regime (HRT of about 4 d, duration of aerobic and anoxic phases of 30 min each) was able to remove up to 90% of total nitrogen and up to 64% of COD tot from the anaerobic effluents under 17-20 degrees C. The coagulation experiments with Fe(III) showed that 1.4 mg of resting hardly biodegradable COD and 0.5 mg of phosphate (as P) could be removed from the aerobic effluents by each milligram of iron added.     

厌氧悬浮填料生物膜反应器处理费托合成废水

采用厌氧悬浮填料生物膜反应器工艺对费托合成废水进行处理,考察了高有机负荷条件下系统的运行情况.有机负荷小于31.1g/(L·d)时,COD去除率达97%以上;当有机负荷从39.7g/(L·d)增加至56.3g/(L·d)时,厌氧反应对COD的去除率从88%降至6l%.实验结果表明,填料生物膜比悬浮污泥具有更高的活性,M...     

A Novel Approach for Phosphorus Recovery and No Wasted Sludge in Enhanced Biological Phosphorus Removal Process with External COD Addition

In enhanced biological phosphorus removal (EBPR) process, phosphorus (P) in wastewater is removed via wasted sludge without actual recovery. A novel approach to realize phosphorus recovery with special external chemical oxygen demand (COD) addition in EBPR process was proposed. During the new operating approach period, it was found that (1) no phosphorus was detected in the effluent; (2) with an external addition of 10 % of influent COD amount, 79 % phosphorus in the wastewater influent was recovered; (3) without wasted sludge, the MLVSS concentration in the system increased from 2,010 to 3,400 mg/L and kept stable after day 11 during 24-day operating period. This demonstrates that the novel approach is feasible to realize phosphorus recovery with no wasted sludge discharge in EBPR process. Furthermore, this approach decouples P removal and sludge age, which may enhance the application of membrane bioreactor for P removal.     

Salicylic-Acid-Mediated Enhanced Biological Treatment of Wastewater

Activated sludge represents a microbial community which is responsible for reduction in pollution load from wastewaters and whose performance depends upon the composition and the expression of degradative capacity. In the present study, the role of salicylic acid (SA) has been evaluated for acclimatization of activated sludge collected from a combined effluent treatment plant followed by analysis of the physiological performance and microbial community of the sludge. The biodegradative capacity of the acclimatized activated sludge was further evaluated for improvement in efficiency of chemical oxygen demand (COD) removal from wastewater samples collected from industries manufacturing bulk drugs and dyes and dye intermediates (wastewater 1) and from dye industry (wastewater 2). An increase in COD removal efficiency from 50% to 58% and from 78% to 82% was observed for wastewater 1 and wastewater 2, respectively. Microbial community analysis data showed selective enrichment and change in composition due to acclimatization by SA, with 50% of the clones showing sequence homology to unidentified and uncultured bacteria. This was demonstrated by analysis of partial 16S rDNA sequence data generated from dominating clones representing the metagenome which also showed the appearance of a unique population of clones after acclimatization, which was distinct from those obtained before acclimatization and clustered away from the dominating population.     

Anaerobic biological treatment of dye bearing water in anaerobic sequencing batch reactor: Performance and kinetics studies

Textile and dye industries are main sources of dye bearing effluent. In present studies the anaerobic biological degradation of Acid Red 3BN dye water (AR3BNDW) and mixed dye water (MDW) for reduction of color and COD were studied in sequential batch reactor (SBR). The sludge as sources of microorganism was arranged from maize processing bio methanation wastewater treatment plant, which was acclimatized for treatment of AR3BNDW and MDW. After the acclimatization, dyes degradation were studied in SBR At optimum operation condition of hydraulics retention time (HRT) = 2.5 d, and treatment time (t_R) = 16 h, AR3BNDW have gone maximum 87% color reduction of 500 mg/L dye, and 82.8% COD reduction of 380 mg/L COD. At same operating condition, 84.5% color reduction of 500 mg/L dye, and 79.42% COD reduction of 413 mg/L COD achieved for MDW. The second order Grau model was fitted well for COD and dye reductions. The kinetics parameter were evaluated for both the dye water.     

Decomposition of Organic Compounds in Coke Plant Wastewater by Ultrasonic Irradiation and Its Combined Process

The paper deals with the degradation of the organic compounds in the coke plant wastewater by the com-bined process of ultrasonic irradiation and activated sludge. The influence factors of the ultrasonic degrada-tion effect such as air atmosphere, initial concentration, ultrasonic power density and the category and con-sumption of catalyst were investigated. A water quality model was used to explain the degradation of differ-ent kinds of organic compounds in the coke plant wastewater by ultrasonic irradiation. After the wastewater was treated by the combined process of ultrasonic irradiation and activated sludge, the COD degradation effi-ciency was 95.74%, which is 63.49% higher than that by the process of activated sludge alone.     

Treatment of opium alkaloid containing wastewater in sequencing batch reactor (SBR)—Effect of gamma irradiation

Aerobic biological treatment of opium alkaloid containing wastewater as well as the effect of gamma irradiation as pre-treatment was investigated. Biodegradability of raw wastewater was assessed in aerobic batch reactors and was found highly biodegradable (83–90% degradation). The effect of irradiation (40 and 140 kGy) on biodegradability was also evaluated in terms of BOD₅/COD values and results revealed that irradiation imparted no further enhancement in the biodegradability. Despite the highly biodegradable nature of wastewater, further experiments in sequencing batch reactors (SBR) revealed that the treatment operation was not possible due to sludge settleability problem observed beyond an influent COD value of 2000 mg dm^?3. Possible reasons for this problem were investigated, and the high molecular weight, large size and aromatic structure of the organic pollutants present in wastewater was thought to contribute to poor settleability. Initial efforts to solve this problem by modifying the operational conditions, such as SRT reduction, failed. However, further operational modifications including addition of phosphate buffer cured the settleability problem and influent COD was increased up to 5000 mg dm^?3. Significant COD removal efficiencies (>70%) were obtained in both SBRs fed with original and irradiated wastewaters (by 40 kGy). However, pre-irradiated wastewater provided complete thebain removal and a better settling sludge, which was thought due to degradation of complex structure by radiation application. Degradation of the structure was observed by GC/MS analyses and enhancement in filterability tests.     

Effect of Microalgae/Activated Sludge Ratio on Cooperative Treatment of Anaerobic Effluent of Municipal Wastewater

In this work, capability of the green microalga (MA), Chlorella vulgaris, in treating synthetic anaerobic effluent of municipal wastewater was investigated. While pure C. vulgaris (100 % MA) provided maximum soluble chemical oxygen demand (sCOD) and N???NH ₄ ⁺ removal efficiencies of 27 and 72 % respectively, addition of activated sludge (AS) to MA in different mass ratios (91, 80, 66.7, 9 % MA) improved wastewater treatment efficiency. Thus giving maximum sCOD and N???NH ₄ ⁺ removal efficiencies 85 and 86.3 % (for MA/AS?=?10/1), respectively. Utilizing AS without C. vulgaris, for treating the synthetic wastewater resulted in 87 % maximum sCOD and 42 % maximum N???NH ₄ ⁺ removal efficiencies. Furthermore, algal growth and specific growth rates were measured in the systems with microalga as the dominant cellular population. As a result, faster algal growth was observed in mixed systems. Specific growth rate of C. vulgaris was 0.14 (day^?1) in 100 % MA and 0.39 (day^?1) in 80 % MA. Finally, data gathered by online measurement of dissolved oxygen indicate that algae-activated sludge mixture improves photosynthetic activity of examined microalga strain during anaerobic effluent treatment.     

Entrapped mixed microorganisms to treat organic wastewater from food industry

Limited land and insufficient technicians to operate a wastewater treatment system are main restrictions for many factories. Therefore, an ideal wastewater treatment method for a small or land-limited factory must possess merits such as high performance efficiency, high organic loading rate, little odor, simple operation, easy maintenance, and little land required (simultaneously). An entrapment technique to immobilize mixed microorganisms to treat organic wastewater, which was developed in the present work, possesses these characteristics. This project was done on a laboratory scale. The microorganisms were activated sludge (an undefined mixture of microorganisms obtained directly from a domestic wastewater treatment plan) and the mixed microorganisms were immobilized in cellulose triacetate by means of an entrapment technique to treat organic wastewater from food industry. After wastewater was treated by this system, the SCOD (soluble COD) removal efficiency of 81% evaluated samples exceeded 80% in 1.5 ± 0.9 g SCOD/L/d of the volumetric loading rate and 7–10 h for the hydraulic retention time. This wastewater treatment method can be applied to other organic industrial wastewater.     

Olive mill wastewater treatment by a pilot-scale subsurface horizontal flow (SSF-h) constructed wetland

Performances of a pilot-scale reed bed for the olive mill wastewater (OMW) treatment were investigated, by monitoring influent and effluent pH, total suspended solids (TSS), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), total phosphorus and polyphenols. In order to reduce the suspended matter concentration and to avoid clogging, OMW was pre-treated by adding lime putty, calcium hydroxide and hydraulic lime. The best results were obtained with 2 g/L of hydraulic lime. Pre-treated OMW was dosed in the reed bed at dilution ratios of 1/3 and 1/10 (v/v), pointing up that the latter only did not give rise to reed suffering and allowed to obtain good and durable removal efficiencies, above all for COD (74.1+/-17.6%) and polyphenols (83.4+/-17.8%). Recycling of the effluent was quite effective for the improvement of the wastewater quality, allowing a further removal of 26-70%, depending on the parameter taken into account. A post-dosage study, carried out by feeding the reed bed with the effluent of an activated sludge plant, pointed up a rapid decreasing of the outlet concentrations of the investigated parameters to values compatible with Italian regulations concerning wastewater discharge in surface water. Polyphenols were the exception, being their outlet concentration at the end of post-dosage study around 2 mg/L.     

超高效液相色谱-串联质谱法检测微氧生物脱氮菌群酰基高丝氨酸内酯信号分子

为揭示处理低碳氮比废水的微氧活性污泥系统的生物脱氮机制,了解脱氮功能菌群的群体生长和代谢规律,建立了超高效液相色谱-串联质谱同时定量检测介导革兰氏阴性(G-)细菌群体感应信号分子酰基高丝氨酸内酯( AHLs)的方法。取自升流式微氧活性污泥反应器的泥水混合物,使用乙酸乙酯液液萃取,旋转蒸干后以甲醇定容,经C18色谱柱分离。以5 mmol/L乙酸铵(含0.1%甲酸)和甲醇为流动相进行梯度洗脱,采用多反应离子监测模式,使用配有电喷雾离子源的三重四极杆质谱进行检测。对9种AHLs的检测结果表明,在0.5~100μg/L范围内呈现良好的线性关系,检出限为0.01~0.5μg/L,回收率为62.5%~118.1%,相对标准偏差为2.9%~12.1%,分析时间为6.5 min。本方法具有快速、准确和精密等特点,可及时反映活性污泥功能菌群的生长状态和代谢活性,对了解生物脱氮系统的生物学机制和废水生物处理系统的运行调控具有重要意义。