Selective adsorption of tetracycline by β-CD-immobilized sodium alginate aerogel coupled with ultrafiltration for reclaimed water

In this work,a novel composite material based on β-cyclodextrin-immobilized sodium alginate aerogel(β-CD/NaAlg) was developed utilizing cross-linker of epichlorohydrin and applied as an adsorbent to remove tetracycline antibiotics from reclaimed wastewater.A series of characterizations were utilized to confirm the successful synthesis of the adsorbent and this β-CD/NaAlg presented a three-dimensional network at the nanoscale or microscale.Under optimal conditions(pH=4,t=8 h,β-CD:NaAlg=9,adsorbent dosage = 1.5 g·L-1),the maximum removal rate of β-CD/NaAlg to tetracycline was 70%.The adsorption behavior of tetracycline on β-CD/NaAlg conformed to the Freundlich isotherm model(R2=0.9977) and the pseudo-second-order kinetic model(R^(2)=0.9993).Moreover,the adsorbent still removed 55.3% of tetracycline after five cycles.Specially,the adsorbent was integrated with ultrafiltration to adsorb tetracycline antibiotics from simulated reclaimed wastewater,and the removal rate of tetracycline reached 78.9% within 2 h.The existence of Cr(Ⅵ) had a negligible impact on tetracycline removal,while the presence of humic acid exhibited a promoting effect.The possible adsorption mechanisms were also elucidated through X-ray photoelectron spectroscopy and density functional theory analysis.In summary,β-CD/NaAlg represents an environmentally friendly,efficient,and sustainable adsorbent for removing tetracycline antibiotics from reclaimed water.

Impacts of Irrigation with Reclaimed Water on Endophytic Bacteria in Chinese Cabbage in Urumqi City

[Objective] This study aimed to investigate the feasibility of agricultural irri- gation with reclaimed water in Urumqi City. [Method] Chinese cabbages were used as experimental materials and irrigated with control water, 50% reclaimed water and 100% reclaimed water, and then the number of endophytic bacteria in Chinese cab- bages was measured. [Result] Using 50% reclaimed water, the fresh weight of Chi- nese cabbage was improved by 68.94%; however, with the deepening internalization of exogenous microorganism internalization, the total number of endophytic bacteria and coliform flock in Chinese cabbages treated with 50% reclaimed water was sig- nificantly higher than the other two treatment groups （P〈0.05）. [Conclusion] Re- claimed water enhances both the weight of Chinese cabbage and the number of endophytic bacteria, which is unsuitable for irrigation of edible crops such as Chi- nese cabbage. Strengthening disinfection during the process of sewerage treatment could solve this problem.

Effects of reclaimed water irrigation and nitrogen fertilization on the chemical properties and microbial community of soil

The ecological effect of reclaimed water irrigation and fertilizer application on the soil environment is receiving more attention.Soil microbial activity and nitrogen（N）levels are important indicators of the effect of reclaimed water irrigation on environment.This study evaluated soil physicochemical properties and microbial community structure in soils irrigated with reclaimed water and receiving varied amounts of N fertilizer.The results indicated that the reclaimed water irrigation increased soil electrical conductivity（EC）and soil water content（SWC）.The N treatment has highly significant effect on the ACE,Chao,Shannon（H）and Coverage indices.Based on a 16S ribosomal RNA（16S rRNA）sequence analysis,the Proteobacteria,Gemmatimonadetes and Bacteroidetes were more abundant in soil irrigated with reclaimed water than in soil irrigated with clean water.Stronger clustering of microbial communities using either clean or reclaimed water for irrigation indicated that the type of irrigation water may have a greater influence on the structure of soil microbial community than N fertilizer treatment.Based on a canonical correspondence analysis（CCA）between the species of soil microbes and the chemical properties of the soil,which indicated that nitrate N（NO3-–-N）and total phosphorus（TP）had significant impact on abundance of Verrucomicrobia and Gemmatimonadetes,meanwhile the p H and organic matter（OM）had impact on abundance of Firmicutes and Actinobacteria significantly.It was beneficial to the improvement of soil bacterial activity and fertility under 120 mg kg^-1 N with reclaimed water irrigation.

Impact of artificial waterfall using reclaimed water to VOCs and its health risk assessment

To study the impact of an artificial waterfall using reclaimed water on volatile organic compounds （VOCs） in air, air samples around the waterfall sight and over the CASS pond of a wastewater treatment plant were collected and VOCs were analyzed by MC-MS with USEPA Method TO-14. The total volatile organic compounds （TOVCs） concentration of a background sample is 2112 μg/m^3, and the sample over the CASS pond has a TVOC concentration of 1858μg/m^3. The TVOC concentrations of air samples within 10 m of the artificial waterfall are between 3216 μg/m^3 and 6362 μg/m^3, which are 1.52 - 3.0 times that of the background sample. The VOCs in air sample impacted by reclaimed water or waste water exhibit a relatively high proportion of toluene but low proportion of benzene. B/T/E/X （ Benzene/Toluene/Ethylbenzene/Xylene ） ratio of the air sample around the artificial water fall is（O. 36/11.78/1/1.10）. Health risk assessment （HRA） was done with the USEPA four-step approach. The result indicates that the artificial waterfall using reclaimed water indeed leads to the increase of human risk value. The total risk value of the sample around the waterfall is 2. 8 - 1.6 times that of the background sample. However, the total risk value of the air sample around the waterfall （2. 8 × 10^-6 ） for common people is still lower,compared to the acceptable public risk level（ 10^-5 ）. For occupational workers of the wastewater treatment plant, the sum of lifetime non-carcinogenic and carcinogenic risk values （ 1.26 × 10^ -5 ） is higher than that of the acceptable public risk level.

Migration of Heavy Metal Elements in Reclaimed Irrigation Water-Soil-Plant System and Potential Risk to Human Health

[Objectives]To study the impact of heavy metal pollution of soil and plants during the process of reclaimed water for irrigation of green land in arid areas and the potential health risks to humans during use.[Methods]Taking Zhongwei City in Ningxia,a typical arid area,as the research area,the irrigation water,soil and green grass in the reclaimed water irrigation region and the original green water irrigation region were sampled,the heavy elements Hg,As,Zn,Pb,Cd,Cr were detected,and the Nemerow method,biological absorption coefficient,and health risk assessment were employed to evaluate the degree of soil pollution,plant absorption capacity,and human health risks.[Results]Compared with the original green water,the Hg,Cd,and Cr pollution of the reclaimed water irrigated green land was higher,the As,Zn,Pb pollution was lower,and the content of Hg and Cd was higher than the environmental background values of soil in Ningxia;the Cr content exceeded the risk intervention values of the first type of land in the Soil Environmental Quality—Risk Control Standard for Soil Contamination of Development Land(GB 36600-2018).Compared with the original green water irrigation region,it is found that the reclaimed water irrigation reduced the heavy metal pollution of the soil to a certain extent.The heavy metal content of tall fescue grass(Festuca arundinacea)in the reclaimed water irrigation region was Zn,Cr,Pb,As,Cd,and Hg from high to low;the order of the biological absorption coefficient was Cd>As>Zn>Pb>Hg>Cr;irrigation water exerted a certain effect on the content of heavy metals in plants and the biological absorption coefficient through the soil.Using the health risk assessment method recommended by Environmental Protection Agency of the United States of America(USEPA),it was found that the reclaimed water has the highest risk through the inhalation route,and the occupational population has a higher risk of skin contact with soil and plants.[Conclusions]This study is intended to provide data support and theoretical basis for the environmental safety risk research of the application of reclaimed water in arid areas to urban greening.

Study of Wastewater Advanced Treatment and Reclaimed Water Reuse for a Large General Hospital

A combined process of biological aerated filter,fiber ball filter and chlorine dioxide disinfection was used to treat effluent of primary hospital wastewater in Jinan.Its treatment capacity was designed as 400m^3/d based on the reclaimed water demand of the large general hospital.The quality of the effluent can meet the requirements of the Reuse of Urban Recycling Water——Water Quality Standard for Urban Miscellaneous Water Consumption(GB/T18920-2002).The project has less site area,low investment and operation cost and high automatic control level,so it can provide scientific references for design and operation of similar projects.

Enhanced Nutrient Removal with Upflow Biological Aerated Filter for Reclaimed Water

A two-stage upflow biological aerated filter was designed as an advanced treatment process to optimize the operating parameters and study the correlative factors influencing the efficiency of nitrification, denitrification and phosphorus removal. The experimental results showed that the final effluent of the two-stage upflow biofilter process operated in series could meet the stringent limits of the reclaimed water for the total nitrogen of 2 mg/L, and total phosphorus of 0.3 mg/L. The high treatment efficiency allowed the reactor operating at very high hydraulic loadings and reaching nearly complete nitrification and denitrifieation.

Orthogonal experiment on reclaimed water treatment and economic optimization model in green building

The efficacy of superior drainage in green building treated by combinational technique of coagulation sedimentation and constructed wetland was launched. The results show that the regression equation relating to effluent BOD5,cubage load (Nv),temperature (t) and addition dosage (ρ) is BOD5=2.05Nv-0.41t-0.82ρ+38.9. The orthogonal experiment results of constructed wetland post-treatment show that the regression equation relating to effluent BOD5,cubage load (NA),and temperature (t) is BOD5=1 190NA-0.32t+12.2. Based on the two orthogonal regression equations,combined of green building municipal gray reclaimed water quantity requirements in different seasons,a technology investment on economic optimization model of combinational technique was established. The results offer technological support for reclaimed water treatment,which regards superior drainage as the source and is purified by combinational technique of coagulation sedimentation and constructed wetland. According to the model,the reasonable scale of reclaimed water treatment systems can be determined,the treatment efficacy can be well predicted,and both the design and operating can be effectively guided.

Influence of Irrigation with Reclaimed Water on Antioxidant System of Maize and Soybean

Irrigation with reclaimed water is an important way to deal with water shortage of agricultural production and solve the problem of sewage pollution. The response of crop antioxidant enzyme system is an early-warning indicator of environmental factors changes. Compared with raw wastewater and used fresh water as controls, this research studied peroxides （POD）, superoxide dismutase （SOD） activities and malondialdehyde （MDA） content in leaves from maize （Zea mays L.） and soybean （Phaseolus vulgaris L.） with pot culture under irrigating with reclaimed water which with secondary and third treatment. The results showed that secondary reclaimed water had some adverse effects on antioxidant system of maize in seedling stage, and the influence decreased in later stage of maize; effect of the third reclaimed water on antioxidant system of maize was not significant. Irrigation with reclaimed water has little influence on antioxidant system of soybean in seedling and reaping stage, but it could bring some oxidative stress in blossom stage. As a result, irrigating maize with second or third reclaimed water is safe to the growth of maize and soybean, but it is suggested that second reclaimed water should not be used in seedling stage of maize and reclaimed water should not be used in the second stage of soybean.

Experimental Study on the Heavy Metal Pollution in the Soil Irrigated by Reclaimed Water from Sewage Treatment Plant

Reclaimed water irrigation is one of the potential ways of solving the shortage of water resources,and the pollution risk on migration behavior of heavy metals in the soil which are irrigated by reclaimed water and the related soil surface is still short of research. Through the experimental study of different kinds of water irrigation methods on vegetable,it can be concluded that compared with sewage irrigation and tap water irrigation,reclaimed water irrigation does not pollute the soil,and it greatly saves the cost of water resources,and even provides a large number of growth elements for vegetables. The results show that after leaching by reclaimed water for 60 days,Cr,Cd,As,Hg,Pb,Ni,Zn and Cu from reclaimed water are enriched in soil to a certain degree,but with the leaching time extending,concentrations of the heavy metal remain stable. The variation of heavy metal content in soil irrigated by reclaimed water is small in vertical depth,basically showing a horizontal trend. According to Soil Environmental Quality Standards( GB15618- 1995),soil irrigated by reclaimed water does not exceed the standard,better than soil quality standard of planting vegetables.

Nitrogen Removal Efficiency of the Reclaimed Water by Land Treatment System

[Objective] The research aimed to study nitrogen removal effect of the land treatment process on reclaimed water. [Method] By using land treatment system, reclaimed water which reached one-level A standard was conducted advanced processing, and nitrogen removal efficiency of the effluent was inspected. [ Result] There was a positive correlation between organic matter content of the soil medium and nitrogen removal effect. With appropriate soil medium, TN and NH3-N could obtain the removal efficiency of more than 90% and 75% respectively, and they could be removed at 30 and 10 cm height of soil medium respectively with land treatment system to treat reclaimed water. [ Conclusion ] The research provid- ed theoretical basis for application of the land treatment system into nitrogen removal of the reclaimed water.

Analysis on Technology Requirements of Garden Irrigation for the Recycling and Use of Reclaimed Water

The lack of water resource is the resource and environmental problem of various countries in the current international environment face, and a better way to solve the shortage of water resource is to adopt the reclaimed water for civil irrigation. But the development of science and technology in China started late, it leads to that our country doesn＇t have deep experience in the use of the reclaimed water application technology, thus, the development and requirements of this technology in the domestic world are very urgent and demanding. In this paper, the author makes a detailed technology requirement explanation for the technology requirement level of supervision, technology, technics and management aspect on wastewater reuse technology.

Microbiological Induced Corrosion on Brass in Recycling Cooling Water System Makeup by Reclaimed Water

The impacts of microorganism on brass corrosion were studied in static experiment in this paper. Two main factors, temperature and concentration ratio, were considered. According to the actual operation of recycling cooling water system, four temperatures (15℃, 25℃, 35℃ and 45℃) and four concentration ratios (1, 2.5, 3.5 and 4.5) were selected in the experiment. Corrosion potential, current density, average corrosion rate were measured by time. The results showed that: Microorganism often aggravated corrosion of brass during initial and final stages, but alleviated its corrosion at the middle time. With the extension of time that brass immersed in the solution, the microbes began to intensify the corrosion of the metal. When concentration ratios were 2.5 and 3.5 and temperature was 15℃, microbe promoted brass corrosion obviously and corrosion degrees.

Effect of Rural Sewage Irrigation Regime on Water-Nitrogen Utilization and Crop Growth of Paddy Rice in Southern China

Reclaimed water irrigation has become an effective mean to alleviate the contradiction between water availability and its consumption worldwide.In this study,three types of irrigation water sources(rural sewage’s primary treated water R1 and secondary treated water R2,and river water R3)meeting the requirements of water quality for farmland irrigation were selected,and three types of irrigation water levels(low water levelW1 of 0–80 mm,medium water level W2 of 0–100 mm,and high water level W3 of 0–150 mm)were adopted to carry out research on the influence mechanismS of different irrigation water sources and water levels on water and nitrogen use and crop growth in paddy field.The water quantity indicators(irrigation times and irrigation volume),soil ammonium nitrogen(NH4+-N)and nitrate nitrogen(NO3−-N),rice yield indicators(thousand-grain weight,the number of grains per spike,and the number of effective spikes),and quality indicators(the amount of protein,amylose,vitamin C,nitrate and nitrite content)of rice were measured.The results showed that,the average irrigation volume under W3 was 2.4 and 1.9 times of that under W1 and W2,respectively.Compared with R3,the peak consumption of rice was lagged behind under R1 and R2,and the nitrogen form in 0–40 cm soil layers under rural sewage irrigation was mainly NH4+-N.The changes of NO3−-N and NH4+-N in the 0–40 cm soil layer showed the trend of declining and then increasing.The water level control only had a significant effect on the change of NO3−-N in the 60–80 cm soil layer.Both irrigation water use efficiency and crop water use efficiency were gradually reduced with the increase of field water level control.The nitrogen utilization efficiency under rural sewage irrigation was significantly higher than that under R3.Compared with the R3,rural sewage irrigation could significantly increase the yield of rice,and as the field water level rose,the effect of yield promotion was more obvious.It was noteworthy that the grain of rice under R1 monitored the low nitrate and nitrite content,but no nitrate and nitrite was discovered under R2 and R3.Therefore,reasonable rural sewage irrigation(R2)and medium water level(W2)were beneficial to improve nitrogen utilization efficiency,crop yield and crop quality promotion.

Assessing Quality of Reclaimed Urban Wastewater from Algarrobo Municipality to Be Used for Irrigation

In the European Mediterranean area, the lack of available water resources had led to consider the reclaimed urban waters as an integral part of water resources. Reclaimed urban waters could mitigate water shortage, support agriculture sector and protect rivers and groundwater resources. This work is focused on the evaluation of reclaimed urban water (RW) from Algarrobo municipality, which is located in the Málaga province in the Mediterranean coast at South-East of Spain. Wastewater in the municipal waste water treatment plant, was treated by a membrane bioreactor (MBR) as a tertiary treatment. The main goal of this work was to determine the composition of RW to be compared with fresh local water (LW) from the Algarrobo River, in order to evaluate its suitability for irrigation. Electrical conductivity (EC), pH, sodium absorption ratio (SAR), and mineral content were weekly measured from September 2017 until June 2018. Assessment of RW quality was carried out considering the limit values for each parameter as stated by the current Spanish legislation RD 1620/2007 for reuse of reclaimed water and European Directive for water reuse (EU 91/271/EEC, Annex I). The MBR facility was also focused on preserving essential minerals for plant nutrition to use them for crop fertilization instead of commercial fertilizers. The average content of nitrogen, phosphorous and potassium were, respectively, 72%, 65% and 46% of the amount needed for the Hoagland 1/4 strength solution that was used in this study for irrigation of tomato, avocado and mango crops. From this study it appears that it is possible using membrane technology, to treat urban wastewater in order to supply a good quality of water for irrigation. Water analysis has also proved MBR to be efficient for removal of microbiological pollutants, inorganic compounds, some trace elements and heavy metals. The assessment of RW shows that the evaluated parameters of water-quality are within the range of values stated by Spanish legislation and the current European Directive for secure use of reclaimed water for irrigation.

环境因子对河流底泥-水界面氮释放规律影响

潮白河作为北京重要城市河流水源之一,其顺义减河河段属于典型的再生水回补河道。研究不同点位代表的自然河段与再生水河段中底泥-水界面的养分释放规律及其影响因素,对河道水质改善具有重要意义。该研究通过室内土柱模拟实验,分析不同p H、溶解氧(DO)和温度条件下河道不同断面底泥氨氮释放规律,估算了底泥-水界面氨氮释放通量。结果表明:(1)下游汇流(S1)、潮减交汇处(S2)和自然河道(S3)上覆水和间隙水中NH4+-N呈明显的释放趋势,再生水河道中段(S4)和再生水排水口(S5)释放不明显或发生NH4+-N吸附作用。(2)不同断面土柱模拟中,间隙水中NH4+-N通量为上覆水的2.5~66.7倍,验证了底泥氮先释放到间隙水再扩散到上覆水的过程。(3)不同环境因子(p H、DO和温度)对底泥NH4+-N释放的影响呈现出不同规律:随p H升高,底泥NH4+-N释放通量先降低后增加,在p H=7时达到最低值;随DO浓度增加,底泥NH4+-N释放通量减小,DO浓度为3 mg/L时NH4+-N释放通量最大;温度越高,NH4+-N释放通量越大。潮白河水体在酸性或碱性条件下,DO浓度越低,温度越高,NH4+-N释放通量越大,该研究结果可为潮白河水质改善提供参考。

鞍钢鲅鱼圈焦化废水减量及回用改造实践

介绍了鞍钢鲅鱼圈焦化废水处理工艺运行概况,分析了焦化废水工艺存在的问题,通过提升预处理单元、生化处理系统和深度处理系统的功能,新增膜脱盐处理系统,大大提升了焦化废水系统出水水质,中水回用率达到70%以上。最终膜脱盐处理系统的浓水水质指标达到了《炼焦化学工业污染物排放标准》(GB 16171—2012)中的间排标准,全部回用于烧结混料,净水全部回用于循环水系统,实现了焦化废水零排放的目标。

农村生活污水原污水、再生水灌溉对林地植物生长及土壤理化性质的影响

为研究农村生活污水原污水和再生水灌溉对林地植物生长和土壤质量的影响,选择优良的速生树种,以107杨、2001杨、2025杨、苏柳172、苏柳799、中科1号构树、中科2号构树、中科3号构树8种人工林为研究对象,分别灌溉农村生活污水原污水、再生水和地下水,统计分析土壤中物理性质(容重、土壤孔隙度、土壤含水量)和化学性质(有机质、全氮、全磷、速效钾、pH值、氯离子、交换性钠)等理化性质变化规律。结果表明,再生水灌溉下土壤容重最小,孔隙度最大,含水量最高。土壤有机质、全氮、全磷、氯离子、交换性钠含量原污水最高,再生水次之,地下水最低;土壤速效钾含量原污水最高,地下水次之,再生水最低。林木生长量、土壤有机质含量杨树最高;土壤的全氮、速效钾、氯离子含量构树最高;交换性钠含量柳树最高;各处理下土壤pH值均为弱碱性。再生水灌溉下杨树、柳树、构树长势和土壤质量改善效果明显,可作为优良树种在农业污水处理“生物生态”组合上推广应用。

再生水投入与长江和黄河流域经济发展的互馈效应研究

基于面板向量自回归模型,收集了2011—2020年长江和黄河流域18个省(自治区、直辖市)的面板数据,在验证了面板数据的有效性基础上,分析了模型的结果、脉冲响应函数及方差分解结果,考察了再生水投入与长江和黄河流域经济发展之间的相互作用及动态双向影响。结果表明:再生水投入与长江和黄河流域经济发展之间具有相互促进、共同发展的关系,并具有区域差异性特征;在流域经济发展对再生水投入的影响上,黄河流域的依赖性明显大于长江流域;在再生水投入对流域经济发展的影响上,黄河流域和长江流域整体上均呈现正向影响,但长江流域正向影响滞后性更强。

再生水灌溉对园林植物、土壤和浅层地下水水质的影响

为研究再生水灌溉对几种常规园林植物、土壤和浅层地下水水质的影响,试验于2017—2020年在河北省石家庄市栾城区洨河湿地东侧的绿化带内,筛选梧桐、榆树、女贞、月季、马莲、鸢尾和海棠等7种常规园林植物进行再生水灌溉。结果表明:同自来水灌溉对照相比,再生水灌溉的7种常规植物叶片中N、P、K和Na的含量增大了1.4%~37.7%;微量元素含量增加了0.7%~48.5%;重金属元素Cr和Cd的含量增大了1.9%~22.9%;Cu的含量增加了4.4%~22.7%;再生水灌溉的土壤全盐量、Na+和pH的增大不明显,而氯化物含量增加了25.1%~86.3%。7种常规植物土壤养分较对照均略有增加,但差异不大。洨河再生水灌溉条件下7种常规园林植物均长势较好,未见有生长异常现象,土壤没有产生明显的恶化,地下水除总硬度外均符合标准,但应进行长期的监测。