Environmental sustainability opportunity and socio-economic cost analyses of phosphorus recovery from sewage sludge

Although phosphorus(P)recovery and management from sewage sludge are practiced in North America and Europe,such practices are not yet to be implemented in China.Here,we evaluated the environmental sustainability opportunity and socio-economic costs of recovering P from sewage sludge by replacing the current-day treatments(CT;sludge treatment and landfill)and P chemical fertilizer application(CF)in China using life cycle assessment and life cycle costing methods.Three potential P recovery scenarios(PR1‒PR3:struvite,vivianite,and treated sludge)and corresponding current-day scenarios(CT1‒CT3 and CF)were considered.Results indicated that PR1 and PR2 have smaller environmental impacts than the current-day scenarios,whereas PR3 has larger impacts in most categories.PR3 has the lowest net costs(sum of internal costs and benefits,39.1-54.7 CNY per kg P),whereas PR2 has the lowest external costs(366.8 CNY per kg P).Societal costs for production and land use of 1 kg P by P recovery from sewage sludge(e.g.,∼527 CNY for PR1)are much higher than those of P chemical fertilizers(∼20 CNY for CF).However,considering the costs in the current-day treatments(e.g.,∼524 CNY for CT1),societal costs of P recovery scenarios are close to or slightly lower than those of current-day scenarios.Among the three P recovery scenarios,we found that recovering struvite as P fertilizer has the highest societal feasibility.This study will provide valuable information for improved sewage sludge management and will help promote the sustainable supply of P in China.

Prediction of second-order rate constants between carbonate radical and organics by deep neural network combined with molecular fingerprints

Carbonate radical is among the most important environmental relevant reactive species which govern the transformation and fate of pharmaceutical contaminants(PCs).However,reaction rate constants between carbonate radical and most of the PCs have not been experimentally determined,and quantitative structural-activity relationships(QSARs)have not been established for rate estimation.This study applied Max Min data processing method and used molecular fingerprints(MF)as the input of a deep neural network(DNN)to predict the rate constants between carbonate radical and organic compounds.MF parameters and the hyper-structure of the DNN were adjusted to yield satisfactory accuracy of rate prediction.The vector length of 512 bits with radius of 1 for MF and 5 hidden layers gave the best performance.The optimized MaxMin-MF-DNN model was compared with some of the most commonly used QSARs and machine learning methods,including random data splitting,molecular descriptors,supporting vector machine,decision tree,etc.Results showed that the MF-DNN model out-performed the other methods by more than 10%increase in prediction accuracy.Applying this MF-DNN model,we estimated reaction rates between carbonate radical and pharmaceuticals used in human medicine(1576)and veterinary practice(390).Among them,46 drugs were identified as fast-reacting compounds,suggesting the important relations of their environmental fate with carbonate radical.

Enhanced formation of trihalomethane disinfection byproducts from halobenzoquinones under combined UV/chlorine conditions

Halobenzoquinones(HBQs)are highly toxic disinfection byproducts(DBPs)and are also precursors of other DBPs such as trihalomethanes(THMs).The formation of THMs from HBQs during chlorine-only and UV/chlorine processes with or without bromide was investigated experimentally.Density functional theory(DFT)reactivity descriptors were also applied to predict the nucleophilic/electrophilic reactive sites on HBQs and intermediates.The results were combined to explain the different behaviors of 2,6-dichloro-1,4-benzoquinone(2,6-DCBQ)and tetrachloro-1,4-benzoquinone(TCBQ)and to propose mechanism for the promoting roles of UV and hydroxylation of HBQs in THMs formation.Under UV/chlorine,UV significantly enhanced THMs formation from 2,6-DCBQ compared to chlorine-only,mainly due to the production of OH-DCBQ^(*).Excited 2,6-DCBQ^(*)by UV benefited nucleophilic hydrolysis to produce OH-DCBQ^(*),which favored electrophilic attack by chlorine,thereby inducing more THMs formation.UV/chlorine modestly promoted THMs formation from TCBQ compared to chlorine-only.Hydroxylation of TCBQ and UV irradiation were both important in promoting THMs formation due to the high electrophilic property of OH-TCBQ and TCBQ^(*).Meanwhile,hydroxylation of HBQs and CHCl3 formation were enhanced at higher pH.This work suggested that enhanced formation of THMs from HBQs should be considered in the application of combined UV and chlorine processes.

Performance of an ANAMMOX reactor treating wastewater generated by antibiotic and starch production processes

飞行员规模厌氧的氨氧化(ANAMMOX ) 反应堆被用来对待源于金霉素和淀粉生产过程的混合废水。结果，在 272 天的功课上镇定，证明到亚硝酸根， pH，和温度罐头的流入的铵的比率都影响氮移动的效率。到亚硝酸根的流入的铵的比率在 200 mg 敨 ? 下面在集中在大约 1:1 被维持 ? 灡牰慯档 ????