Food processing wastewater purification by microalgae cultivation associated with high value-added compounds production——A review

Microalgae have been considered as an efficient microorganism for wastewater treatment with simultaneously bioenergy and high value-added compounds production.However,the high energy cost associated with complicated biorefinery(e.g.microalgae cultivation,harvesting,drying,extraction,conversion,and purification)is a critical challenge that inhibits its large-scale application.Among different nutrition(e.g.carbon,nitrogen and phosphorous)sources,food processing wastewater is a relative safe and suitable one for microalgae cultivation due to its high organic content and low toxicity.In this review,the characteristic of different food wastewater is summarized and compared.The potential routes of value-added products(i.e.biofuel,pigment,polysaccharide,and amino acid)production along with wastewater purification are introduced.The existing challenges(e.g.biorefinery cost,efficiency and mechanism)of microalgal-based wastewater treatment are also discussed.The prospective of microalgae-based food processing wastewater treatment strategies(such as microalgae-bacteria consortium,poly-generation of bioenergy and value-added products)is forecasted.It can be observed that food wastewater treatment by microalgae could be a promising strategy to commercially realize waste source reduce,conversion and reutilization.

Heavy Metal Contaminated Food Crops Irrigated with Wastewater in Peri Urban Areas, Zambia

Studies on peri urban farming in Zambia have not adequately tackled the issues pertaining to heavy metal contaminated wastewater irrigation farming. The study investigated heavy metal contamination of water, soils and crops at two peri urban areas in Zambia. Two study sites were New Farm Extension in Mufulira Town in the Copperbelt Province and Chilumba Gardens in Kafue Town in Lusaka Province. The heavy metals investigated were lead, copper, cobalt, nickel and chromium. These heavy metals were found to be higher than acceptable limits in wastewater used to irrigate crops and there are potential human health risks associated with consumption of heavy metal contaminated food crops which have implications on the livelihoods of people. Samples of water, soil and crops were collected and analysed for lead (Pb), copper (Cu), chromium (Cr), cobalt (Co) and nickel (Ni) using the Atomic Absorption Spectrometer (AAS). The data on heavy metals was analysed using mean, standard error and T-test. The results indicated that the levels of heavy metals in wastewater, soil and food crops were above acceptable limits at two study sites. It can be concluded that there was heavy metal contamination of wastewater, soil and food crops at the two peri-urban areas in Zambia. The study highlighted the actual levels of heavy metal contaminant uptake in food crops consumed by the peri urban population. The information from this study can be used by the relevant authorities to develop appropriate measures for monitoring and control of heavy metal contamination in wastewater irrigation farming systems in peri urban areas inZambia.

Wastewater irrigation and crop yield:A meta-analysis

Although wastewater irrigation in agriculture could be a potential adaptation to water scarcity, its effect on crop yield varies in the literature, making it difficult to evaluate its role in global food security comprehensively. Using agronomic experiment data from 62 studies between 1987 and 2021, we employ a meta-analysis to analyze the factors contributing to the heterogeneous effects of wastewater irrigation on crop yield. Our findings can be summarized as(1) the mean yield growth effect of wastewater irrigation is 19.7%;(2) domestic and breeding wastewater irrigation could significantly increase crop yield, while industrial wastewater has a negative effect although not significant;(3) high nutrients concentration of domestic wastewater is significantly positively correlated with crop yield;(4) agronomic experiment designs in terms of field experiment, experiment times, and fertilizer use could contribute to the divergent crop yield effects across the studies;(5) there is a publication bias of the research results between the English and Chinese literature;(6) the literature mainly sheds light on the short-run effect, and the long-run impact shall be an important research question in the future.

A review of modified and hybrid anaerobic baffled reactors for industrial wastewater treatment

This review discusses high-strength wastewater treatment using anaerobic baffled reactors(ABRs)and modified ABRs.The research findings and applications of ABRs in treating various types of high strength wastewater generated from food companies,livestock,and industries were summarized and reported.Measurement parameters affecting the performance of ABRs are briefly discussed.The state-of-the-art laboratory studies are compiled and critically reviewed.Critical challenges and suggestions for future investigation are also addressed.

生化-超滤-纳滤组合工艺在餐厨垃圾废水处理中的应用

采用除渣预处理+厌氧反应器+二级AO+外置式超滤+NF(双膜法)组合工艺进行餐厨垃圾废水处理,研究结果表明,当进水COD为72315~78562 mg/L时,NF系统产水COD为264~347 mg/L,对有机物的去除率达到99.5%~99.7%,研究了NF系统压力、温度、pH和运行时间对膜分离性能的影响。NF出水可以达到《污水排入城镇下水道水质标准》(GB/T 31962-2015)标准B等级指标,NF系统浓水用于静脉产业园垃圾焚烧炉飞灰固化。最后,对工程投资、运行费用和经济效益进行了分析和讨论。

日本核废水排海对我国水产品进出口的影响及对策研究

日本政府宣布核废水排海,其生产的水产品安全性难以保证,中国政府禁止进口日本水产品势必对中日水产品进出口贸易产生重要影响,主要包括对我国出口市场的冲击、进口安全风险的加剧及对日贸易政策的调整。基于2015—2023年中日水产品贸易现状,本文运用对比分析法分析2023年我国对日本水产品进出口月度数据,研究核废水排海前后中日水产品进出口的变化情况,发现禁止进口日本水产品对我国水产品贸易既是挑战又是机遇,据此本文提出可以通过建立严格的核污染水监管机制、加强海洋环境管理与保护工作、发展国内水产品等策略降低核废水造成的不良影响,以供参考。

含盐食品工业废水脱氮除磷性能研究

为研究含盐食品工业废水脱氮除磷的性能,将不同盐度(NaCl)引入实验室模拟食品工业废水处理系统中,选择厌氧/缺氧/好氧(A/A/O)的运行方式,考查处理系统中化学需氧量(COD)、NH_(4)^(+)-N、NO_(3)^(-)-N、NO_(2)^(-)-N、PO_(4)^(3-)-P等理化指标的变化情况,并结合污泥性质和功能微生物菌群结构揭示不同盐度对食品工业废水脱氮除磷性能的影响机理。结果表明,引入盐度既能提高系统中有机物的去除效果,COD去除率从84.08%增大至90.33%,还能促进厌氧阶段除磷菌释磷及硝化作用,NH_(4)^(+)-N去除率从95.79%增大至98.85%,但会抑制除磷菌好氧吸磷性能;低盐度(0.5g/L)能够促进系统反硝化性能,但当盐度升高至3.0g/L时,会降低系统反硝化性能;随着盐度的升高,微生物胞外聚合物(EPS)含量增大,当盐度为3.0g/L时,EPS含量为38.81mg/gVSS;引入盐度还会增加微生物菌群的相对丰度,改变微生物菌群结构,促进Chloroflexi、Actinobacteriota和Planctomycetota等反硝化菌门富集,同时随着盐度的升高,Caldilineaceae、Ferruginibacter、Kouleothrix等功能微生物的相对丰度增大,而Candidatus_Competibacter的相对丰度降低,这保证了含盐系统稳定的脱氮除磷效果。

双膜法在食品废水深度处理中水回用工程中的应用

采用双膜法(超滤+反渗透)对某食品企业污水站二沉池出水进行深度处理,处理后的中水回用至卫生间及冷却塔,达到节约自来水的目的。二沉池出水先进碟滤系统,去除大颗粒悬浮物(SS)后再进超滤系统。在进入超滤系统前加入次氯酸钠,降低化学需氧量引起的有机物污堵。单套超滤膜装置产水量为20 m^(3)/h,共2套,回收率在90%左右,产水浊度在0.3NTU以下。反渗透进水中添加阻垢剂、还原剂,避免膜被氧化,单套反渗透装置产水量为14m^(3)/h,共2套,回收率在70%左右。反渗透产水电导率低于80uS/cm,符合中水回用水质要求。

高级氧化技术在食品工业废水处理的研究进展

食品工业产生的含脂肪族、芳香族、糖类、酚类等有机废水,具有机物含量高,难降解,成分复杂等特点。若不经处理直接排放会严重污染环境。高级氧化技术能有效去除废水中难降解有机物,通过产生强氧化性的原位自由基,将食品工业废水中有机污染物矿化成为H_(2)O、CO_(2)等小分子物质。对电化学氧化、芬顿、臭氧氧化、光催化氧化、空化、过硫酸盐氧化法等食品工业废水处理方法的研究,并展望高级氧化技术在食品工业废水处理领域研究前景和发展趋势。

易腐垃圾沼液作为污水处理厂补充碳源的资源化利用探索——以浙江某污水处理厂为例

低强度进水制约了城镇污水处理厂的总氮(TN)脱除效果。采用易腐垃圾沼液作为补充碳源,在强化污水处理厂脱氮效果的同时,降低了污水处理和易腐垃圾沼液运行成本及碳排放量。实验分析了沼液成分,并研究了不同沼液/进水混合比对污染物去除、运行稳定性及污泥性状的影响。结果表明,当混合比为0.100%(体积分数)时,工艺具有最佳运行效果。沼液投加后生化段反硝化速率增加了2.23倍,同步硝化反硝化(SND)效率增加了39.2%,TN去除率提高了1.34倍。污水处理厂出水水质稳定,达到《城镇污水处理厂主要水污染物排放标准》(DB 33/2169—2018)(“准四类”排放标准)。工艺流程中重金属(Pb、Cd及Cr)含量均未超标,出水的环境污染风险可控。沼液的资源化利用每年约减少污水处理厂运行成本38万元,易腐垃圾运行成本144万元,并削减近84 t CO_(2)排放。结果表明,对易腐垃圾沼液的资源化利用“以污治污”,有助于碳减排目标的实现,降低了运行成本,并具有良好的社会和环境效益。

O+A/O-MBBR一体化装置处理食品加工废水工程实例

针对某食品加工废水COD和氨氮浓度高,可生化性好,固体杂质含量高的特点,采用O+A/O-MBBR一体化装置进行处理。介绍了废水处理工艺流程、主要工艺单元设计参数、运行效果及运行费用。工程运行结果表明,O+A/O-MBBR一体化装置运行稳定,处理后的食品加工废水满足GB 13457—1992《肉类加工工业水污染物排放标准》中表3肉制品加工一级排放标准的要求(ρ(COD)≤80 mg/L,ρ(氨氮)≤15 mg/L),废水处理费为3.6元/m^(3)。

肉制品废水AO生化处理工艺调试研究

中国人无法停下对美食追求的脚步,越来越多的工厂为了制作美食崛地而起。在我国快速发展食品工艺的同时,水污染也成了一个不可忽视的问题,净化废水成为迫在眉睫的一件事情。课题组采用改进的AO工艺法对红毛鸡爪厂的废水进行处理,文章在原水水质分析的基础上,采用三阶段法对项目的水质工程进行调试分析。研究结果表明低负荷挂膜;提负荷适应;原水适应的三阶段调试方法,成功进行了工程项目调试。挂膜效果明显,镜检发现了漫游虫、轮虫、钟虫等指示污泥系统的改善及指示污泥处理效果好的微生物,废水中的总磷、氨氮、SS、CODCr去除效果明显,且结果显示调试后排出的废水达到(GB18918-2002)《城镇污水处理厂污染物排放标准》一级排放标准。

涡凹气浮+改良Bardenpho+磁混凝沉淀应用于食品加工类污水处理厂准Ⅳ类出水

根据食品加工类废水为主的市政污水厂进水有机污染物浓度高但易生物降解、氮磷浓度高的特点,同时考虑出水标准严格的情况,设计采用了“预处理+涡凹气浮+改良Bardenpho+磁混凝沉淀+反硝化滤池+次氯酸钠消毒工艺”的工艺方案,工程设计中选用的工艺和设备注重节约能耗和药耗,减少运行成本。详细介绍了处理工艺方案选择、工艺特点和各处理单元的工程设计参数,同时对实际运行情况进行了总结。项目投产后运行稳定良好,出水水质完全达到了地方要求的准Ⅳ类水质标准。

食品工业废水处理实践

食品工业废水的主要特点是有机型污染,可生化性较好,水质水量不稳定,废水中COD、BOD5、氨氮、总磷及动植物油浓度较高。现行的国家标准和地方管理对排放水质要求较高。因此,去除废水中的有机物、悬浮物的同时,高效的脱氮、除磷,确保出厂废水达到排放标准要求是工艺设计的关键所在。文章简要介绍了废水的产生环节、主要污染指标和源强,“格栅+隔油沉淀+调节+气浮+IC厌氧塔+A/O+沉淀”的工艺思路、工艺过程的设计参数、主要配套设备及建成后的运行情况。建成后出水水质可以满足《污水综合排放标准》(GB8978-1996)表4二级标准要求及产业集聚区污水处理厂接管标准要求。

某食品废水厌氧处理技术节能效果与经济效益评估

以某食品厂为实例,对比在厌氧+好氧MBR与单独好氧MBR工艺中,厌氧技术的节能效果和经济效益。结果表明,单独好氧MBR和厌氧+好氧MBR对于食品废水中有机污染物的降解效果均较好,COD去除率分别达到98.02%和98.93%;单独好氧MBR吨水运行能耗为7.33k Wh/m3,而厌氧+好氧MBR吨水运行能耗为3.64kWh/m3,约节50.34%的运行能耗。单独好氧MBR吨水处理费用约为7.244元/m3;厌氧+好氧MBR不计沼气的收益,吨水处理费用为3.262元/m3,计入沼气收益吨水运行费用为0.291元/m3,经济效益显著。

西安市餐厨垃圾提油废水的资源化利用

餐厨垃圾提油废水富含有机质和油脂,蕴含热能,同时兼具水资源属性。为合理利用餐厨垃圾提油废水,避免资源浪费,降低运营成本,西安市餐厨垃圾资源化利用和无害化处理项目总结一期经验,在二期应用厌氧产沼发电、用作稀释水、用作生产冲洗水、余热利用、用作沼液生化系统碳源等方式,将餐厨垃圾提油废水充分资源化利用。二期发电量与一期持平,厌氧产沼发电量均为35 000 kW·h/d。相较于一期,二期节约用水25 t/d,节省蒸汽36%,节省碳源50%,提高提油量20%,真正做到变废为宝。

预处理+高效厌氧+A/O+MBR+NF组合工艺处理餐厨垃圾废水工程实例

以某餐厨垃圾废水处理工程为例介绍一种“预处理+高效厌氧+A/O+MBR+NF”的组合工艺并详细说明了工艺流程和设计参数。餐厨垃圾废水经该工艺处理后主要出水水质可达到《污水综合排放标准》(GB 8978—1996)中的一级标准水质要求,COD_(Cr)、BOD_(5)、NH_(3)-N、SS去除率可分别达到99.88%、99.95%、99.60%、100%。此外针对项目存在的膜污染、浓缩液处置等问题进行论述并提供解决思路,对类似项目具有一定指导意义。

食品废水处理填料结垢分析及工艺改造实践

生物接触氧化池能否稳定运行对整个污水生物处理系统的稳定性有着至关的重要性,而结垢问题是影响接触氧化工艺稳定运行的主要因素之一。处理过程中CaCO_(3)等垢体的形成将抑制生物膜的形成和生长,导致处理性能下降。因而,对含钙废水采取合理有效防止CaCO_(3)结垢的措施,具有重要的实际意义。文章对贵州某食品公司生物接触氧化法污水处理过程中填料结垢的问题进行分析,探讨填料结垢机理及影响CaCO_(3)垢形成的相关因素,并提出处理对策,为类似项目提供参考。

O+A/O-MBBR工艺系统对食品加工废水处理特性研究

构建O+A/O-MBBR工艺系统试验装置对食品加工废水进行处理。研究不同温度(T)、填充率(PR)、溶解氧(DO)、水力停留时间(HRT)、回流比(R)对O+A/O-MBBR工艺系统污染物去除性能的影响。结果表明,O+A/O-MBBR工艺系统在20℃、PR为35%、DO为4.5 mg/L、HRT为16 h和R为200%条件时,对COD、氨氮、总氮浓度分别为1035.3~1360.8 mg/L、 116.2~143.6 mg/L、124.4~168.2 mg/L,pH为6.8~7.3的食品加工废水有较好的处理效果(去除率分别为94.04%、91.73%和76.18%),处理后的废水达到《肉类加工工业水污染物排放标准》(GB13457-1992)中的标准。

Treatment of wastewater from food waste hydrothermal carbonization via Fenton oxidization combined activated carbon adsorption

Hydrothermal carbonization(HTC)of food waste can produce hydrochar for further utilization as high-quality fuel or carbon materials,but the by-product of liquid effluent,named HTC wastewater,has a high chemical oxygen demand(COD)content and other organic pollutants.This study focused on the feasibility of Fenton oxidation combined with activated carbon(AC)to reduce COD in HTC wastewater.The effects of different parameters including pH,dosage of hydrogen peroxide,molar ratio of Fe^(2+)/H_(2)O_(2),and reaction time were tested and discussed.Eventually,through the optimized Fenton oxidation(pH=3,H_(2)O_(2)dosage=1.5 mol/L,Fe^(2+)/H_(2)O_(2)=1:15,reaction time=60 min)combined optimized AC adsorption process(AC dosage=30 g/L),the COD value reduced from 42,000 mg/L to 3075 mg/L,indicating a COD removal efficiency of 92.7%and a color removal ratio of 91.9%,respectively.The comparison of GC/MS(gas chromatography mass spectrometer)and FTIR(Fourier transform infrared spectrometer)of liquid residual from different treatment methods also indicated that the types of organic substances in HTC wastewater were significantly reduced through Fenton oxidation and AC adsorption.