Optimization and evaluation of an air-recirculated stripping for ammonia removal from the anaerobic digestate of pig manure

An air-recirculated stripping involved two processes and did not require any pretreatment. First, stripping CO₂ decreased the buffer capacity of the anaerobic digestate, thereby reducing the amount of lime used to achieve a high pH. Second, lime was added to increase pH and remove ammonia from the anaerobic digestate of pig manure. pH increased from 8.03 to 8.86 by stripping CO₂ in the first process (gas-to-liquid ratio = 180) and further reached 12.38 in the second process (gas-to-liquid ratio = 300). During process optimization, the maximum ammonia removal efficiency reached 96.78% with a lime dose of 22.13 g. The value was close to 98.25%, which was the optimal result predicted by response surface methodology using the software Design-Expert 8.05b. All these results indicated that air-recirculated stripping coupled with absorption was a promising technology for the removal and recovery of nitrogen in the anaerobic digestate of pig manure.     

Anaerobic digestion modeling of the main components of organic fraction of municipal solid waste

The organic fraction of municipal solid waste (OFMSW) is composed of several heterogeneous organic and inorganic wastes. The diversity of composition, the high volatile solid content and the biodegradable material that this waste offers make it quite an interesting option for anaerobic digestion (AD). Depending on the substrate composition, the biological degradation and kinetics of the AD could vary. Biochemical methane potential (BMP) tests are used as a tool to evaluate the methane production of several fractions of OFMSW, in order to study the influence of each fraction in the final mixture. The kinetic parameters of methane curves and the prediction of final productions are studied by different approaches to model equations using linear, exponential, logistic and Gaussian models. The analyses of the fractions indicate that organic substrates such as meat/fish which are in a small proportion in the final mixture, obtain major productivities (291 ± 3 mlCH₄/gVS), however others such as paper (217 ± 5 mlCH₄/gVS) could have their productivity enhanced due to their high VS present in the final mixture. Both the Gomperzt and the first order model fit reasonably with all the fractions, although substrates with lag phase adjust only to the Gompertz model explaining 99% of the experimental results.     

Investigation of affecting parameters on treating high-strength compost leachate in a hybrid EGSB and fixed-bed reactor followed by electrocoagulation–flotation process

In this research, treatability of high-load compost leachate in a hybrid expanded granular sludge bed (EGSB) and fixed-bed (FB) bioreactor followed by electrocoagulation–flotation (ECF) system was examined. The operational factors in EGSB–FB were influent chemical oxygen demand (COD), hydraulic retention time (HRT) and COD/nitrogen ratio (COD/N). And, their interactive effects on the efficiency of COD removal and biogas production rate (BPR) as responses were analyzed and correlated by response surface methodology (RSM). The optimum conditions of the hybrid EGSB–FB reactor were acquired at COD = 7800 mg/L, HRT = 35 h, COD/N = 70, in which COD removal efficiency was 83% and BPR 94 mL/h. The amount of confidence interval was 95%. COD (relevant coefficient = 9.8) and HRT (relevant coefficient = −24) were resulted respectively as the most effective parameters on COD removal and BPR. Yet, COD/N parameter imposed negative effect on COD removal and BPR in values less than about 100. The outcomes indicated that operated ECF as post-treatment in constant conditions (electrolysis time = 75 min, electrodes distance = 3 cm, voltage = 20 V) successfully satisfied discharge criteria in the most part of experimental domains.     

碳源及电子受体对厌氧微生物降解对氯硝基苯的影响

为考察氯代硝基苯的共代谢降解过程中,有机碳源类型和电子受体对氯代硝基苯厌氧降解过程的影响,以对氯硝基苯(p-CNB,para-chloronitrobenzene)为目标污染物,通过间歇试验考察了葡萄糖、乙醇、乙酸钠等有机碳源及SO2--4、NO3等竞争性电子受体对厌氧微生物降解对氯硝基苯的影响。结果显示,葡萄糖、乙醇和乙酸钠作为碳源时,菌种获得的还原能力大小依次为:乙醇葡萄糖乙酸钠。SO2-4对菌种降解对氯硝基苯过程不产生竞争性抑制。NO-3对对氯硝基苯降解过程的影响与碳源的量有关,当乙醇-COD为100 mg/L时,硝酸盐产生竞争性抑制,且抑制作用随着NO-3浓度升高而增强;当乙醇-COD为600 mg/L时,硝酸盐对菌种降解对氯硝基苯过程不产生竞争性抑制作用。     

絮凝沉淀-内电解-厌氧生物氧化预处理DDNP废水

二硝基重氮酚（DDNP）废水是一种严重污染环境和危害人体健康的难降解工业废水。采用絮凝沉淀-内电解-厌氧生物氧化组合工艺预处理DDNP废水,主要考察了内电解反应的进水pH值、反应时间、铁屑与焦炭的质量比和厌氧池停留时间对DDNP废水CODCr去除效果的影响。小试结果表明：以内电解的进水pH值为3,反应时间为120 min,铁屑与焦炭的质量比为12及厌氧池的停留时间为40 h为最佳工艺条件,在此条件下DDNP废水的CODCr去除率可达82.5%,并显著改善其可生化性。     

Anaerobic-aerobic treatment of purified terephthalic acid (PTA) effluent; a techno-economic alternative to two-stage aerobic process

This paper addresses the treatment of purified terephthalic acid (PTA) effluent using anaerobic and aerobic processes. Laboratory studies were carried out on flow proportionate composite wastewater generated from the manufacturing of PTA. An activated sludge process (ASP-two stage and single stage) and an upflow anaerobic fixed film fixed bed reactor (AFFFBR) were used, individually and in combination. The performance of a full-scale ETP under existing operating conditions was also studied. Full scale ETP studies revealed that the treatment of PTA effluent using a two-stage ASP alone does not meet treated effluent quality within the prescribed Indian Standards. The biomass produced in the two stage ASP was very viscous and fluffy and the sludge volume index (SVI) was very high (200-450 ml/g). However, pretreatment of PTA effluent using an upflow AFFFBR ensured substantial reduction in BOD (63%) and COD (62%) with recovery of biogas at 1.8-1.96 l/l effluent treated at a volumetric loading rate (VLR) 4-5 kg COD/m(3) d. The methane content in the biogas varied between 55% and 60%. The pretreated effluent from the upflow AFFFBR was then treated through a single stage ASP. The biomass produced in the ASP after anaerobic treatment had very good settlability (SVI: 75-90 ml/g) as compared to the two stage ASP and the treated effluent quality with respect to BOD, COD and SS was within the prescribed Indian Standards. The alternative treatment process comprising an upflow AFFFBR and a single stage ASP ensured net power saving of 257 kW and in addition generated 442 kW of power through the AFFFBR.     

Anaerobic treatment of industrial wastewaters

Anaerobic processes are widely used for treatment of organic wastes. Fixed-film anaerobic processes are capable of handling high organic loads due to higher biomass concentration in the form of biofilms. Anaerobic biofilm reactor startup is greatly influenced by environmental, cellular and surface factors, and is often hindered by low growth rates of anaerobes and their strict environmental requirements. However, these obstacles can be overcome by applying appropriate startup strategies.     

Performance of a combined anaerobic reactor for municipal wastewater treatment at ambient temperature

A bench-scale experimental study was carried out to investigate the overall performance of a combined anaerobic reactor for treating pre-settled municipal wastewater at ambient temperature (18–28°C) in terms of substrate removal efficiencies, biogas, methane production, volatile fatty acid (VFA) profiles and effluent suspended solids (SS) concentration, etc. The tested reactor was a modified anaerobic baffled reactor (ABR). The second and third compartments were partly packed with supporting media. The experimental results were similar to, or compared favourably with, other anaerobic reactor systems for municipal wastewater treatment at ambient temperature and proved the technical feasibility of this compartmentalised reactor. Considering its simple structure and operation, it could be considered a potential reactor system for treating municipal and domestic wastewaters in tropical and sub-tropical areas of developing countries.     

A technology for the treatment of olive-mill waste water in a continuously fed plant

A bench-scale pilot plant has been developed for the treatment of olive-mill water. The plant is fed in a continuous mode and implements a primary treatment (sand filtering and irradiation with UV-rays) and a secondary treatment (anoxic and aerobic biological treatment). Satisfactory results were obtained and the treated green water falls under the limits of the Italian legislation. Veratric and ferulic acid biodegradation were studied under anoxic conditions in order to verify the requirements for optimal biodegradation. Electronic Publication     

硫酸盐对厌氧生物处理的影响及控制对策

对硫酸盐对厌氧生物处理过程影响机理进行了深入的分析，并由此提出了高浓度硫酸盐废水处理的可行方法及控制对策。