Continuous removal of hydrogen peroxide with immobilised catalase for wastewater reuse.

Hydrogen peroxide was continuously removed for wastewater reuse using an immobilised biocatalyst. A commercial catalase, which is an enzyme to decompose hydrogen peroxide to water and oxygen, was entrapped in chitosan beads. Hydrogen peroxide in aqueous solutions of varying pH, temperature and concentration was continuously removed through a reactor containing the catalase-entrapped chitosan beads at high efficiency for 24 h. Additional silicate coating of the chitosan beads resulted in significant improvements in the catalase performance under harsh conditions, which are often found in peroxide-based industrial processes. We expect that immobilisation of catalases can enhance their applicability for continuous degradation of hydrogen peroxide for wastewater reuse.     

Use of immobilised bacteria for the wastewater treatment--examples from the sugar industry.

This work focuses on the implementation of high performance systems to the wastewater treatment of sugar factories. For this purpose, systems with immobilised bacteria were studied. For the hydrolysis of organic matter and denitrification, fluidized bed reactors were used. The nitrification was studied with an airlift reactor system. Both hydrolysis and nitrogen elimination were investigated on laboratory and pilot scales in sugar factories. Although with porous materials higher biomass concentrations are attainable for the hydrolysis (up to 55 kg/m3), for economical reasons sand was used (22.5 kg/m3) for the pilot scale-study. With a pilot-scale reactor (volume 1 m3) the maximum sucrose conversion rate achieved with sand in the first campaign was 52 kg/(m3 d). For the nitrogen elimination on the pilot scale, a system with denitrification and nitrification was combined. The highest performance for the nitrification (reactor volume: 0.68 m3) with pumice as support material was 1.2 kg NH4-N/(m3 d), limiting the whole system. The denitrification rate (reactor volume: 0.12 m3) was four times higher (3.5-5 kg NO3-N/(m3 d). Rules of the modelling of the system are discussed.     

Reuse of industrial wastewater for the irrigation of ornamental plants.

This paper describes the results of experimental activities carried out for verifying the possibility of reusing reclaimed wastewater originated from textile (70%) and domestic (30%) activities for the irrigation of container-grown ornamental shrubs. Aspects that concern the refinery treatment of reclaimed wastewater and the effect of irrigation on some ornamental plant species were investigated. An experimental site consisting of a refinery treatment pilot plant (filtration and disinfection) and an agronomic experimental area was set-up. The combined treatment of PAA and UV, used for the disinfection, showed to be very effective for inactivation of E. coli with most of PAA and UV dose combinations able to assure total inactivation. The plants (Buxus, Photinia, Pistacia and Viburnum), sprinkle and drip irrigated with well water (WW), reclaimed wastewater (RW) and a water mixed (MW) between reclaimed wastewater and well water (1:1 by vol), showed interesting results. A similar growth among different treatments was achieved for Buxus and Pistacia, while Viburnum and Photinia plants showed a higher sensibility to MW and RW. Photinia, in particular, turned out to be very sensitive to sprinkle irrigation with the reclaimed water, while the drip irrigation had no such bad effects, as reported in previous works.     

Optimization of photo-Fenton process of RO concentrated coking wastewater using response surface methodology

The objective of this study was aimed at investigating the removal of chemical oxygen demand (COD) from reverse osmosis (RO) concentrated coking wastewater by the photo-Fenton process. The optimum extraction conditions for the photo-Fenton process by Box-Behnken design (BBD) and response surface methodology (RSM) to establish a predictive polynomial quadratic model were discussed based on a single factor test. Optimized parameters validated by the analysis of variances (ANOVA) were found to be H(2)O(2) concentration of 345.2 mg/L, pH value of 4.1 and reaction time of 103.5 minutes under ultraviolet irradiation. The experimental results of the COD removal under the optimized conditions presented better agreement with the predicted values with deviation error of 3.2%. The results confirmed that RSM based on BBD was a suitable method to optimize the operating conditions of RO concentrated coking wastewater.     

高浓度有机废水处理工程改造

某化工厂的生产废水有机物浓度高且可生化性低,属难处理废水.原采用"水解酸化-SBR-兼氧"为主体的处理工艺,因未进行充分的预处理,工艺无法正常运行.为此进行改造,强化预处理.中试表明,矿化度降低44.4%,CODCr去除率达72%,BOD/COD由0.18提高到0.38.在此基础上提出了改进方案,包括采用微电解-絮凝工艺来强化预处理,增设中沉池,改造某些处理构筑物,并强化了系统调控.改造后出水能达标排放,运行成本为2.1元/m3.     

Reuse of wastewater effluent for irrigation in severely arid regions

Al‐Hassa oasis, with an estimated population of 750000, is one of the main agricultural areas in Saudi Arabia. The estimated present agricultural water consumption in the oasis is almost 419 × 10⁶ m³ per year and the water is mainly supplied from the aquifer systems in the oasis. The climate is severely arid and the groundwater resources are limited. A deficiency in irrigation water supplies would occur in the oasis, especially during the summer season, without the reuse of wastewater effluent. Alternative schemes were developed on the basis of climatic, irrigation method, crop, health and economic considerations for the potential reuse of wastewater effluent for irrigation purposes. The schemes suggested different alternatives for reuse of the untreated effluent or with various types of additional treatments needed to render the water free of health hazards and suitable for agricultural use. An expected average wastewqter effluent of about 32.2 × 10⁶ m³/year will be available for irrigation purposes. This will result in minimizing the mining of groundwater and in conserving the water resources in Al‐Hassa oasis.     

Reuse of wastewater sludge with marine clay as a new resource of construction aggregates.

The disposal of sludge from wastewater treatment presents highly complex problems to any municipality. Most of the sludge disposal methods have varying degrees of environmental impact. Hence, it is necessary to explore potential areas of reuse in order to alleviate sludge disposal problems and to conserve natural resources. Industrial sludge and marine clay are two forms of high-volume wastes. Using these wastes as a resource of raw materials to produce construction aggregates would enable large-scale sludge reuse. The aggregates were produced at various sludge-clay combinations containing 0, 20, 50, 80 and 100% clay contents, respectively. The pelletized aggregates displayed lower particle densities ranged between 1.48 and 2.25 g/cm3, compared to the density of granite at 2.56 g/cm3. Good 28-day concrete compressive strength of 38.5 N/mm2 achieved by the 100% sludge aggregate was comparable to the value of 38.0 N/mm2 achieved of the granite control specimens. The leachate contamination levels from the aggregates after 150 days were found acceptable when used in concrete, indicating insignificant environmental contamination. The heat flow study showed increases in heat flow at the temperatures of 480 degrees C and between 660 degrees C and 900 degrees C, indicating a need for the extension of heating time around these temperatures.     

去除反渗透浓水中有机物的研究进展

随着污水管理及排放要求的日益严格,反渗透浓水(ROC)的处置及处理是反渗透工艺面临和亟待解决的关键问题。对其处理工艺,包括混凝/絮凝、高级氧化、磁性离子交换树脂、电容去离子技术和活性炭吸附等,进行综述及分析,比较了各工艺的处理效果及优缺点,探讨了工艺的发展方向。     

高浓度化工废水处理改造工艺中试研究

在对造成原有废水处理工艺出水不达标的原因分析基础上,采用水解+A/O工艺进行高浓度化工废水处理改造工艺中试试验研究。化工废水进水水质为:COD 1200 mg/L,NH_3-N 50mg/L,SS 150mg/L,石油类100 mg/L;地区工业生活污水进水水质为:COD 350 mg/L,NH_3-N 40mg/L,SS 80 mg/L,石油类30 mg/L;经水解+A/O工艺处理后出水水质为:COD 85.3 mg/L,NH_3-N 12.04mg/L,SS 70 mg/L,石油类10 mg/L,实现达标排放。     

Reuse of treated wastewater and sewage sludge for fertilization and irrigation

The objective of the present work was to assess the short-term potential of treated wastewater and sewage sludge for ornamental lawn fertilization and irrigation. A field experiment was performed and the following treatments were considered: sewage sludge application + irrigation with public water; sewage sludge application + irrigation with treated wastewater; irrigation with public water; irrigation with treated wastewater (TW). Irrigation with treated wastewater showed a positive effect on lawn installation through higher growth of grass (1,667 cm) and higher dry matter yield (18,147 g m(-2)). These results represent a significant increase in the grass yield compared with public water irrigation. The grass height (2,606 cm) and dry matter yield (23,177 g m(-2)) increased even more, when sewage sludge produced in the wastewater treatment plant (WWTP) was applied to soil, which proves once more its benefits as an organic fertilizer. At the end of the experiment, an increase of some soil parameters (pH, electrical conductivity, organic matter, Ca2+, Na+, K+, Mg2+ and NH4+) was observed, indicating that treated wastewater irrigation can cause a soil sodization. This short-term study indicated that use of treated wastewater and sewage sludge for ornamental lawn fertilization and irrigation is an environmentally sustainable option for re-use of the WWTP by-products.     

低温下SBR污水处理工艺运行研究

研究了低温和常温条件下SBR系统的运行状况，探索了低温条件下不同有机负荷与曝气时间的对应关系。常温SBR系统启动期为6d，低温系统启动期为8d，每天运行周期均为8h。低温系统的COD去除随曝气时间的变化趋势与常温系统基本相同，与常温系统的运行状况相比，低温系统在相同有机负荷情况下，其出水COD比常温系统稍低，但没有大的区别。常温和低温两种系统中，同一负荷每天出水COD浓度大致相同，但不同有机负荷系统的出水COD显著不同。     

焚烧法处理高浓度有机农药生产废水

农药生产废水属有害工业废水,成分复杂、有机物含量高、生物降解性很差,生化处理难以达标.对某农药厂废水实行分流处理,将高浓度蒸馏浓缩液利用周边电厂的循环流化床焚烧炉焚烧,并对焚烧效果和实际可操作性、经济性进行了分析,证明采用循环流化床焚烧炉焚烧高浓度复杂成分废水是有效、可行的.     

Reuse of drinking water treatment sludge for olive oil mill wastewater treatment

Olive mill wastewater (OMW) results from the production of olive oil, which is an important traditional agro-industry in Mediterranean countries. In continuous three-phase centrifugation 1.0-1.2 m(3) of OMW are produced per ton of processed olives. Discharge of OMW is of serious environmental concern due to its high content of organic matter with phytotoxic properties, namely phenolic compounds. Meanwhile, drinking water treatment sludge (DWTS) is produced in high amounts and has long been considered as a waste for landfill. The aim of this work was the assessment of reusing DWTS for OMW treatment. High performance liquid chromatography (HPLC) analysis was carried out to determine the phenolic compounds present and to evaluate if they are recalcitrant. Treatability assays were performed using a dosage of DWTS from 50 to 300 g L(-1). Treatment efficiency was evaluated based on the removal of chemical oxygen demand (COD), biochemical oxygen demand (BOD), total solids (TS), total suspended solids (TSS), total volatile solids (TVS), oil and grease (OG), phenols (total phosphorous (TP) and HPLC fraction). Results from OMW HPLC characterization identified a total of 13 compounds; the major ones were hydroxytyrosol, tyrosol, caffeic acid, p-cumaric acid and oleuropein. Treatability assays led to a maximum reduction of about 90% of some of the phenolic compounds determined by HPLC. Addition of 200-300 g L(-1) of DWTS reduced 40-50% of COD, 45-50% of TP, a maximum of nearly 70% TSS and 45% for TS and TVS. The OG fraction showed a reduction of about 90%, achieved adding 300 g L(-1) od DWTS. This study points out the possibility of establishing an integrated management of OMW and DWTS, contributing to a decrease in the environmental impact of two industrial activities, olive oil production and drinking water treatment.     

Reuse of carwash wastewater with hollow fiber membrane aided by enhanced coagulation and activated carbon treatments.

The particles from carwash wastewater were separated by a hollow fiber membrane aided by a enhanced coagulation and activated carbon. This study demonstrated that the addition of KMnO(4) to coagulant (PAC) could enhance the efficiency of coagulation, which helped reduce clogging of the ultrafiltration membrane and activated carbon. The existence of LAS can loosen the gel layer on the membrane and improve the flux. Adsorption of particles such as organic matter and oil is the main reason causing membrane flux decrease. When carwash wastewater was pretreated, the permeation flux of membrane showed a higher value. LAS, odour and colour are removed by GAC adsorption treatment at last. The COD, BOD, LAS and oil of reuse water was 33.4 mg/L, 4.8 mg/L, 0.06 mg/L and 0.95 mg/L, respectively.     

移动式污水处理系统应用于分散生活污水的试验研究

针对分散型生活污水量小面广的特点,开发出移动式污水处理系统,系统由生化预处理池和车载式移动污水处理设备组成.中试结果表明,采用该组合工艺,出水CODCr＜40 mg/L,BOD5＜10 mg/L,TP＜0.5 mg/L,TN＜10 mg/L,NH3-N＜1 mg/L,其平均去除率分别达到86.69%,94.89%,89.40%,74.35%和97.89%.出水指标均能达到＜城镇污水处理厂污染物排放标准＞(GB 18918-2002)一级A排放标准.     

Coupled photochemical-biological system to treat biorecalcitrant wastewater.

The aim of the present work is to study a coupled system to treat biorecalcitrant wastewaters. The combination consists of an advanced oxidation process (AOP) named photo-Fenton (Ph-F), which is a photochemical treatment and a sequencing batch biofilter reactor (SBBR). The synthetic wastewater used to optimise this process is a solution of 200 ppm of 4-chlorophenol (4-CP). The first part of the work is the study of the biodegradability enhancement achieved by the photochemical process, measured as the ratio between the biochemical oxygen demand (BOD5) and the chemical oxygen demand (COD). The second step is the start-up and optimisation of the biological process. The results showed that it is necessary to severely treat the toxic solution (with 500 ppm of [H2O2]0) in order to achieve more than 90% of TOC removal in the whole process. The photochemical and biological treatments lasted 50 minutes and 24 hours, respectively.     

芯片生产废水处理技术探讨

通过实地调研,结合工程经验,采用比较分析的方法,就芯片生产废水中典型的含氨废水、含氟废水、研磨废水和酸碱废水的处理分别给出了较优的处理工艺流程,即浓氨吹脱—两段沉淀—三级酸碱中和处理工艺,其处理效果较好,将含氟废水与CMP研磨废水混合处理可节省投资。同时,介绍了设备选型中应注意的问题。     

Pilot-scale studies on biological treatment of hypersaline wastewater at low temperature.

In order to investigate the feasibility of biological treatment of hypersaline wastewater produced from toilet flushing with seawater at low temperature, pilot-scale studies were established with plug-flow activated sludge process at low temperature (5-9 degrees C) based on bench-scale experiments. The critical salinity concentration of 30 g/L, which resulted from the cooperation results of the non-halophilic bacteria and the halophilic bacteria, was drawn in bench-scale experiments. Pilot-scale studies showed that high COD removal efficiency, higher than 80%, was obtained at low temperature when 30 percent seawater was introduced. The salinity improved the settleability of activated sludge, and average sludge value dropped down from 38% to 22.5% after adding seawater. Seawater salinity had a strong negative effect on notronomonas and nitrobacter growth, but much more on the nitrobacter. The nitrification action was mainly accomplished by nitrosomonas. Bench-scale experiments using two SBRs were carried out for further investigation under different conditions of salinities, ammonia loadings and temperatures. Biological nitrogen removal via nitrite pathway from wastewater containing 30 percent seawater was achieved, but the ammonia removal efficiency was strongly related not only to the influent ammonia loading at different salinities but also to temperature. When the ratio of seawater to wastewater was 30 percent, and the ammonia loading was below the critical value of 0.15 kgNH4+-N/(kgMLSS.d), the ammonia removal efficiency via nitrite pathway was above 90%. The critical level of ammonia loading was 0.15, 0.08 and 0.03 kgNH4+-N/(kgMLSS.d) respectively at the different temperature 30 degrees C, 25 degrees C and 20 degrees C when the influent ammonia concentration was 60-80 mg/L and pH was 7.5-8.0.     

Investigation on the behaviour of selected pharmaceuticals in the groundwater after infiltration of treated wastewater.

In a rural arid area without suitable receiving water the treated wastewater of a low loaded municipal wastewater treatment plant with full nutrient removal and additional post treatment steps is infiltrated into the unsaturated soil for groundwater recharge. Groundwater probes at increasing distances from the infiltration point have been sampled every two months over a period of 14 months. Beside conventional parameters (nutrients, carbon, and bacterial counts) samples were analysed for pharmaceutically active substances. Depending on and corresponding to their chemical structure and their fate during wastewater treatment, the selected substances showed different behaviour in the saturated zone of the groundwater. The antiepileptic Carbamazepine behaves very conservative and only is removed negligible even after long flow times within the subsurface zone. For other substances like the tranquilizer Diazepam or the analgesics Diclofenac a partial elimination during the different steps of wastewater treatment can be observed. Further degradation could be observed during the subsequent subsurface passage. In correlation with flow time additional removal of these substances from the aqueous phase can be observed. The musk substances Galaxolide and Tonalide were removed to some extend but not as good as the previous mentioned compounds.