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.     

Performance of constructed wetland treating wastewater from seafood industry.

Wastewater from seafood industry contains high concentrations of organic matter, nitrogen compounds, and solid matter. Constructed wetland can be used as tertiary treatment and for nutrient recycling. This research studied the performance of nitrogen and suspended solids removal efficiency of a constructed wetland treating wastewater from a seafood-processing factory located at Songkhla, southern Thailand. The existing constructed wetland has dimensions of 85 m, 352 m and 1.5 m in width, length and depth respectively, with an area of about 29,920 m2. The water depth of 0.30 m is maintained in operation with plantation of cattails (Typha augustifolia). Flow rate of influent ranged between 500-4,660 m3/d. Average hydraulic retention time in the constructed wetland was about 4.8 days. Influent and effluent from the constructed wetland were collected once a week and analyzed for pH, temperature, dissolved oxygen (DO), biochemical oxygen demand (BOD5), Suspended solid (SS), total Kjeldahl nitrogen (TKN), ammonia nitrogen (NH3-N), organic nitrogen (Org-N), nitrate (NO3-N), and nitrite (NO2-N). The average removal efficiencies of BOD5, SS, TKN, NH3-N, and Org-N were 84%, 94%, 49%, 52% and 82%, respectively. It was found that the constructed wetland acting as a tertiary treatment process provided additional removal of BOD5, SS and TKN from wastewater from the seafood industry.     

Reuse of low concentrated electronic wastewater using selected microbe immobilised cell system.

This work describes a novel technology for the reuse of low concentrated electronic wastewater using selected microbe immobilisation cell (SMIC) system. The SMIC system is an innovative technology to maximise the activity of specific microorganisms capable of decomposing tetramethyl ammonium hydroxide (TMAH) as a major organic compound in the low concentrated electronic wastewater. The versatility of the SMIC system has been studied by using continuous-flow reactors. The TOC in a SMIC system was removed completely, indicating that SMIC is a useful technology to remove TOC biologically in low concentrated wastewater. The most important advantages of this system are highly effective and stable in view of TMAH removal. These characteristics make well suited to various applications depending on targeted compounds and microorganisms and, especially, in the wastewater of electronic facilities.     

Use of nanofiltration for potable water from an aquifer recharged with wastewater.

This paper presents the comparison of nine nanofiltration membranes to treat water coming from an aquifer recharged with wastewater and used as municipal supply in the Tula Valley, Mexico. The comparison was made based on (a) the amount of water produced; (c) the capability to produce a <1 mg TOC/L effluent without entirely eliminating salts, (b) the removal of specific organic and microbiological pollutants, and (c) the reduction of toxicity and mutagenicity from water. From the tested membranes, only four produce an effluent with <1 TOC mg/L, and three totally retained dibutyl phthalate, diethyl phthalate and hydroxytoluene butylate. Influent mutagenicity (Ames test) was negative but these was a certain degree of toxicity when Tetrahymena pyriformis was used as indicator. Toxicity was partially reduced by some of the NF membranes. The best membrane had a flux of 95 L m(-2)h(-1) and removal efficiencies of 98% for TOC, 92% for AUV(254), and 92% for TDS. The permeate had a final hardness of 76 mg/L and an alkalinity of 124 mg/L. Additionally, this membrane removed totally specific organic compounds, total and fecal coliforms and almost all the somatic coliphages.     

Batch experiment on H2S degradation by bacteria immobilised on activated carbons.

Biological treatments of odorous compounds, as compared to chemical or physical technologies, are in general ecologically and environmentally favourable. However, there are some inefficiencies relative to the media used in biofiltration processes, such as the need for an adequate residence time; the limited lifetime, and pore blockage of media, which at present render the technology economically non-viable. The aim of the study is to develop novel active media to be used in performance-enhanced biofiltration processes, by achieving an optimum balance and combination of the media adsorption capacity with the biodegradation of H2S through the bacteria immobilised on the media. An enrichment culture was obtained from activated sludges in order to metabolise thiosulphate. Batch-wise experiments were conducted to optimise the bacteria immobilisation on activated carbon, so as to develop a novel "biocarbon". Biofilm was mostly developed through culturing the bacteria with the presence of carbons in mineral media. SEM and BET tests of the carbon along with the culturing process were used to identify, respectively, the biofilm development and biocarbon porosity. Breakthrough tests evaluated the biocarbon performance with varying gas resistance time, inlet H2S concentration, and type of support materials. Fundamental issues were discussed, including type of support material, mode of bacteria immobilisation, pore blockages, and biodegradation kinetics, etc. This batch-wise study provides a basis for our future research on optimisation of the biofiltration process using a bio-trickling reactor.     

The application of surface engineered silica for the treatment of sugar containing wastewater

The removal of sucrose and fructose from water at various high concentrations by surface engineered silica (SES) was studied using dissolved sugar in pure water. The results indicate that sugar at concentrations of up to 800 g/L can be removed by SES at a relatively high dose of 250 to 300 g/L. Based on these results, process water from a soft drink filling station which was contaminated by sugar, flavour components, Escherichia coli, Pseudomonas aeruginosa bacteria and Candida pelliculosa yeast were treated to study the performance of SES using actual process water samples by analysing turbidity, biological oxygen demand (BOD), UV absorption, and various other standard parameters, and microbial tests. The study shows that at a dose of 100 g/L of SES bacterial contamination as well as turbidity, BOD and UV absorption can be significantly reduced. However, the study found the yeast species Candida pelliculosa could not be removed from the water samples.     

有效微生物菌剂处理淀粉糖废水的试验研究

本试验以有效微生物菌剂为试验材料,以淀粉糖废水为供试样品,通过有效微生物菌剂作用测定淀粉糖废水好氧和厌氧条件下的pH、悬浮物含量(SS)、臭阈值、氨氮含量、化学需氧量(COD)等指标参数,确定该微生物菌剂废水处理最佳菌浓度及处理时间等条件。结果表明:好氧条件下,处理时间为5天,有效微生物菌剂接种量V菌剂/V废水为1/2 500时,废水中的COD由1074mg/L降至165mg/L、氨氮含量由9.30mg/L降至1.63mg/L。对COD、氨氮的最高去除率分别为84%、85.3%。     

Photosynthetic bacteria pond system with infra-red transmitting filter for the treatment and recovery of organic carbon from industrial wastewater.

A photosynthetic bacteria pond system was applied to the treatment of food industrial wastewater and recovery of carbon in the form of purple non-sulphur bacterial (PnSB) cell. The effect of infra-red transmitting filter on the selection of microbial groups in the system was investigated. It was found that more than 90% of organic removal could be achieved when the system was operated at HRT of 3 to 10 days, even though some fluctuations were observed at lower HRT. Infra-red transmitting filter could suppress the growth of microalgae in the system and allow the purple non-sulphur to grow in the system. Nevertheless, they could be outgrown by sulphate-reducing bacteria at higher organic loading rates. The growth of purple sulphur bacteria associated with sulphate reducing bacteria was also observed. ORP is a crucial operating factor to control the system under micro-anaerobic conditions which is preferred to the growth of purple non-sulphur bacteria.     

Application of anaerobic biological treatment for sulphate removal in viscose industry wastewater.

Long term lab-scale and bench-scale experiments were performed to investigate the feasibility of the anaerobic process to treat wastewater from a pulp and viscose fibre industry. Anaerobic wastewater treatment enables an advantageous combination of COD, sulphate and zinc removal from viscose wastewater. The aim of the investigations was to evaluate the influence of the free sulphide concentration on COD and sulphate removal efficiency and on the substrate competition between sulphate reducing and methanogenic bacteria. Since the wastewater did not contain enough COD for complete sulphate removal it was of major interest to determine favourable process conditions to steer the substrate competition in favour of sulphate reduction. Further experiments at bench-scale permitted us to evaluate applicable COD-loading rates and gain fundamental information about process stability and optimization for large-scale implementation. The present work will deal with the most relevant experimental results achieved and with important technological aspects of anaerobic treatment of viscose wastewater.     

Dutch analysis for P-recovery from municipal wastewater.

There is a considerable practical interest in phosphorus recovery from water authorities, elementary P-industry, fertilizer industry and regulators in a number of countries. Due to a handful of full-scale plants worldwide, P-recovery can be seen as technically feasible. However, the economic feasibility of P-recovery from sewage can still be judged as dubious. The most important reason for this is that the prices of the techniques (in euro/tonne P) are much higher compared to the prices of phosphate rock. In this paper an analysis is given to recover phosphate from municipal wastewater for the elementary P-industry Thermphos International B.V. and the fertiliser industry Amsterdam Fertilizers B.V. in The Netherlands. Several scenarios are evaluated and the end products of these scenarios are compared to the quality required by both industries. From a Dutch study it became clear that all end products from the final sludge treatment do not provide a good source of secondary phosphate. As a consequence of this, the most preferred possibility for P-recovery is to extract phosphate before sludge goes to the final sludge treatment. Different scenarios can be selected based on the position of P-recovery in the WWTP configuration, the type of P-recovery product, and the precipitation technique. Local conditions will determine which scenario is the most expedient. Because it is more realistic to judge a practical situation instead of theoretical estimations based on literature, some local situations have to be assessed in sufficient detail to gain more feeling for the expenses and possible savings of P-recovery. One important actor that should be involved in the process management around P-recovery, is the national government. Especially, the Government have the responsibility for sustainable development and should have attention for some stimulation of P-recovery in The Netherlands. Water authorities and the P- and fertilizer industry made already some good steps.     

The fate of metals in forest industry wastewater treatment systems.

The capture/removal of a range of metals was estimated for a number of pulp and paper wastewater treatment systems. Both long-term wastewater data and accumulated sludge data were examined. Only copper and lead were effectively captured (greater than 50%) by all sites and estimate methods. Zinc capture exceeded 50% in all but one case. Qualitatively, iron, aluminium, cadmium, and cobalt were usually captured to a significant extent. The sludge inventory-based approach and the wastewater system inlet-outlet approach gave reasonably similar capture estimates.     

Acrylic acid removal by acrylic acid utilizing bacteria from acrylonitrile-butadiene-styrene resin manufactured wastewater treatment system.

The aim of this study is to isolate the acrylic acid utilizing bacteria from the ABS resin manufactured wastewater treatment system. The bacteria should have the ability to remove acrylic acid and tolerate the acrylonitrile and acrylamide toxicity. The aim is also to understand the performance of isolated pure strain for treating different initial acrylic acid concentrations from synthetic wastewater. The results are: twenty strains were isolated from the ABS resin manufactured wastewater treatment system and twelve of them could utilize 600 mg/l acrylic acid for growth. Seven of twelve strains could tolerate the acrylonitrile and acrylamide toxicity, when the concentration was below 300 mg/l. Bacillus thuringiensis was one of the seven strains and the optimum growth temperature was 32 degrees C. Bacillus thuringiensis could utilize acrylic acid for growth, when the initial acrylic acid concentration was below 1,690.4 mg/l. Besides this, when the initial acrylic acid concentration was below 606.8 mg/l, the acrylic acid removal efficiency exceeded 96.3%. Bacillus thuringiensis could tolerate 295.7 mg/l acrylamide and 198.4 mg/l acrylonitrile toxicity but could not tolerate 297.3 mg/l epsilon-caprolactam.     

臭氧组合工艺深度处理酒精废水

研究了混凝-O3、O3-混凝、混凝-H2O2-O3等臭氧组合工艺对某酒精废水的深度处理效果.结果表明:混凝-O3工艺中臭氧的加入同样可以达到单独混凝所达到的出水效果,处理效率高,减少了混凝剂的投加量,从而减少了产泥量;O3-混凝工艺的试验表明,臭氧对混凝存在促进作用,在相同混凝剂和臭氧投加量的条件下,O3-混凝工艺对有机物的去除效果好于混凝-O3工艺;混凝-H2O2-O3工艺中,H2O2的加入提高了臭氧对CODCr的去除效果,H2O2的投加量存在最优值,在本试验中一次性投加H2O2 165 mg/L时CODCr去除率最高,达75%,比未投加H2O2时对CODCr的去除率提高了45%.H2O2分次投加比一次性投加对CODCr的去除率高,同时,随着臭氧投加量的增加,分次投加与一次性投加对CODCr的去除率差距变小.     

纺织废水处理工程改造

某纺织企业由于产量及生产品种发生变化,其生产废水的污染物浓度增加,因此必须进行工程改造.改造工程充分利用原有设施,采用水解酸化-活性污泥-接触氧化工艺.结果表明,改造后的处理系统对CODCr、BOD5、SS和色度的去除率分别为95.6%、95.7%、83.3%、93.3%,出水达到《纺织染整工业水污染物排放标准》(GB 4287-92)一级标准.     

Photosynthetic bacteria production from food processing wastewater in sequencing batch and membrane photo-bioreactors

Application of photosynthetic process could be highly efficient and surpass anaerobic treatment in releasing less greenhouse gas and odor while the biomass produced can be utilized. The combination of photosynthetic process with membrane separation is possibly effective for water reclamation and biomass production. In this study, cultivation of mixed culture photosynthetic bacteria from food processing wastewater was investigated in a sequencing batch reactor (SBR) and a membrane bioreactor (MBR) supplied with infrared light. Both photo-bioreactors were operated at a hydraulic retention time (HRT) of 10 days. Higher MLSS concentration achieved in the MBR through complete retention of biomass resulted in a slightly improved performance. When the system was operated with MLSS controlled by occasional sludge withdrawal, total biomass production of MBR and SBR photo-bioreactor was almost equal. However, 64.5% of total biomass production was washed out with the effluent in SBR system. Consequently, the higher biomass could be recovered for utilization in MBR.     

硫酸盐还原菌及其在废水厌氧治理中的应用

硫酸盐还原菌(SRB)在废水处理方面有独特的优势,在厌氧环境中能以硫酸盐作为电子受体降解有机污染物。本文阐明了SRB处理废水中污染物的机理,综述了国内外利用SRB处理重金属离子废水、含硫酸盐有机废水和酸性矿山废水的研究进展。最后总结了目前在工程应用方面尚存在的问题。     

印染废水处理及回用实例

某集团印染废水处理采用水解酸化-接触氧化-双膜系统(连续微滤 反渗透),工程运行结果表明:进水CODCr为450～900 mg/L,BOD5为180～350 mg/L、SS为170～340 mg/L,其生化出水CODCr为74～110 mg/L,平均为90 mg/L,BOD5＜20 mg/L,SS＜10 mg/L,优于《污水综合排放标准》(GB 8978-1996)的二级标准;双膜系统(连续微滤 反渗透)出水优于企业染整软水标准,可作为企业染整用水.处理过程不产生固废,实现了废水的零排放.     

制药行业废水改造工程实例

山东某制药企业污水处理工程主体生化采用AO工艺,在实际运行过程中,污泥膨胀严重,出水COD、总氮长期不达标.改造工程优化AO工艺为多级AO,并增加弹性填料.运行结果表明,对COD、总氮的去除率分别达到98.9％、95.2％,出水水质稳定达到园区污水接管标准.     

超声强化铁炭微电解处理制浆造纸废水

考察了超声波、微电解以及其联合作用对制浆造纸废水的处理效果,试验结果表明:微电解法单独处理速率较慢,在pH为4,铁炭质量比为10的条件下,反应120min,CODCr的最大去除率仅为60.6%;在相同的处理条件下,超声强化微电解作用对处理制浆造纸废水有明显的协同效应,反应10min,CODCr的去除率达90%以上,色度的去除率达97.3%,提高了去除率,缩短了处理时间。     

Use of hydrogen peroxide in scrubbing towers for odor removal in wastewater treatment plants.

The aim of this work was to replace sodium hypochlorite (NaCIO) with hydrogen peroxide (H202) in chemical scrubbing towers, in order to avoid the formation of chlorinated species, harmful for human health. Some previous studies have already shown the ability of H2O2 to treat the hydrogen sulfide (H2S) pollution. However, an important decomposition of the oxidant was observed in the scrubbing solution (carbonates, transition metal and high pH are responsible for this decomposition) leading to high reactant consumption. Consequently, this study first focused on research into a compound able to reduce the hydrogen peroxide degradation. Experiments were conducted on a pilot unit (3,000 m3 h(-1)) in a wastewater treatment plant. The sodium silicate (Na2SiO3) proved to be a good scrubbing solution stabilizer. A very good removal of hydrogen sulfide (up to 98%) was also obtained. Finally, the study resulted in the determination of the best operating conditions to achieve both an efficient and economical process.