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.

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.

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.

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.

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.

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.

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.

Sensitivity Analysis of Parameters in Water Quality Models and Water Environment Management

The impacts of changes of various parameters and stochastic factors on water quality models were studied. The impact of deviation of the degradation coefficient on the model results was investigated. The degradation coefficient was decomposed into the exact part and the deviation part, and the relationship between the errors of the water quality model results and the deviation of the degradation coefficient was derived. The impact of changes in the initial concentration on the model results was discussed. A linear relationship between the initial concentration changes and errors in the model results was obtained, and relevant recommendations to the water quality management were made based on the results. The impacts of stochastic factors in the water environment on the water quality model were analyzed. A variety of random factors which may affect the water quality conditions were attributed to one stochastic factor and it was further assumed to be the white noise. The solutions to the water quality model including the stochastic process were obtained by solving the stochastic differential equation. Simulation results showed that the decay trend of the concentration of the solute would not be changed, and that the results would fluctuate around the expectation centered at each corresponding displacement

Architecture Water-saving Design and Building Technique of Sponge Yard

The reclaimed water that we can use in daily life accounts for as much as 35 %,but we do not give it enough concern.The authors focus on the design methods and approaches of green buildings,which refer to water saving and environmental protection.In this paper,the authors illustrate the generating channels of reclaimed water in architecture design:rainwater collection integration design,sewage zero discharge of reclaimed water reused by biological technology,and sponge yard,thereby protecting environment.

Evaluation of the exploitation of nontraditional water resources—Case study of Yantian District in Shenzhen

Yantian District in Shenzhen is a water deficient area. Water shortage has become a major obstacle to its further economic progress. Consequently, rational exploitation of nontraditional water resources(NWR)has been naturally adopted to increase local available water volume. The purpose of this paper is to analyse the exploitation of two kinds of NWR, namely wastewater reuse and seawater utilization, in Yantian District, and assess the contribution of each mode to deal with the water crisis. Two different nontraditional water supply systems respectively based on the reclaimed water and sea water were presented, and the effects of each system were evaluated in terms of technology, economy and environment. The result shows that both wastewater reclamation and reuse (WRR) and direct utilization of seawater (DUS) are of great importance to cope with the tight water resource situation in the district. The data indicate that the fresh water saved by WRR system and DUS system is 29 and 17 million m3/a respectively. Moreover, the BOD, COD, NH3-N and T-P reduced by the WRR system are 870, 2900, 725 and 87 t/a, respectively. Considering the integrated effectiveness, the development of WRR system, which is of specific significance to exploiting new water resource and save natural fresh water supplied from distant water diversion project, is the preferred methods used to solve the water shortage problem in Yantian District and recover the water environment as well as maintain the sustainable development of the city zone.

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.

Research on optimal design of wastewater reclamation and reuse for a university

An optimal design of wastewater reuse for a University is concerned in this paper. The raw water and the capacity of wastewater reuse were determined according to the wastewater characteristic of a university; the treatment process was chosen by building a cost-benefit model; and the modeling test was performed about the operation effect of the proposed project and the recommended water quality of reclaimed water. It is estimated that 3.4×10^5 m^3/a tap water and 6.1×10^5 Yuan/a will be saved if the project was put into operation and the proposed project will reduce the total quantity of pollutant efficiently and bring lots of social and economic benefits.

Ecological and Low-carbon Technology in Urban Decentralized Treatment and Reclamation of Wastewater

China's water shortage situation is grim.Deep exploration of non-traditional water resources and relief of contradiction between China's economic development and water resources shortage is the only way to ensure the sustainable development of China.Urban sewage treatment and reclamation is a more stable and widely used method of non-traditional water resources development and utilization.However,urban centralized reclaimed water treatment faces many problems such as high transportation cost and difficulty in laying reusing pipe network.Relatively speaking,decentralized reclaimed water treatment technology has obvious advantages and is gradually getting more attention.In this research,three types of wastewater treatment process featured with urban decentralized low-carbon ecological technology have been mainly introduced.In addition,the operating data of relevant domestic and foreign engineering cases were analyzed from the perspectives of treatment effect,energy consumption level,applicable scale and occupied area,etc.This study considers that these three new sewage processes based on the principle of ecological engineering have the advantages of compact structure,small footprint,low water consumption,stable effluent quality,beautiful appearance and large applicable scale,and are worthy of researching and importing.