The characterization of biochars derived from rice straw and swine manure, and their potential and risk in N and P removal from water.

Nowadays, the plant residual derived biochars have been widely applied to remove nitrogen (N) and phosphorus (P) from water. However, the application of animal manure derived biochars in N and P removal was less studied. To compare the different efficiency and risk of plant residual- and animal manure-derived biochar in removing N and P from water, this study chose rice straw and swine manure as representative to produce biochar at 700 °C, and modified the produced biochar by MgCl2. Then, the characteristics, removal efficiency and release of N and P of biochars were investigated. The results showed swine manure-biochars generally had higher ash content and cation exchange capacity (CEC), but lower pH and surface area relative to rice straw-biochars. Besides, MgCl2 modification reduced the ash content and surface area of both raw biochars, whereas the pH, CEC and pore size were enhanced. Furthermore, this work demonstrated that ammonium and nitrate could be removed by all biochars to certain extent, and MgCl2 modified biochars generally had higher removal efficiency. However, none of phosphate removal was achieved by all biochars. Additionally, the release of ammonium, nitrate and phosphate from biochars was observed, suggesting there might be a risk for applying biochars in N and P removal from water. Notably, the MgCl2 modification seemed to accelerate N and P release from biochars. This work provided important information that the production and modification of biochars should be carefully designed for higher removal efficiency of pollutants. Meanwhile, the risk of released pollutants as well as the release mechanisms should be paid more attention in the future.

A novel spatiotemporally anaerobic/semi-aerobic bioreactor for domestic solid waste treatment in rural areas.

To meet the requirements of domestic solid waste treatment and technological upgrading of bioreactors, a spatiotemporally anaerobic/semi-aerobic bioreactor (STASAB) was designed. The STASAB took full advantages of anaerobic and semi-aerobic bioreactors by the sequential alternation of anaerobic and semi-aerobic operation and by recirculation of mixed leachate from different-stage bioreactors. Results indicated that after the start-up stage, the pH of leachate in the STASAB always remained higher than 6.88, even in the hydrolysis and acidogenesis stage. The maximum total nitrogen concentration in the STASAB was 1461 mg·L-1, which was merely half that of the sequentially anaerobic/semi-aerobic bioreactor (SASAB) and had no adverse effects on the anaerobic process. Nitrogen removal in the STASAB reached 92.3%-95.5% when operated in the semi-aerobic phase and even reached 49.4% when operated in the anaerobic phase. The peak concentration of chemical oxygen demand was much lower and the anaerobic digestion lag time was much shorter in the STASAB than in the SASAB. The period of rapid biogas production in the STASAB was double that of the SASAB, which resulted in a 70% increase in biogas generation. Moreover, leachate could be exhausted by evaporation in just 3-5 months during the semi-aerobic phase. Therefore, the STASAB can eliminate acidogenic and ammonia inhibition during solid waste treatment, enhance the rate and extent of organic waste decomposition, rapidly initiate methanogenesis, enhance methane generation, and achieve zero leachate discharge (excluding rainfall infiltration). The STASAB is an efficient and feasible technique for treating domestic solid waste in rural areas.

Characteristics and management modes of domestic waste in rural areas of developing countries: a case study of China.

A huge accumulation of domestic waste has caused serious environmental contamination in rural areas of developing countries (RADIC). The characteristics and management of domestic waste are carefully discussed, based on field surveys and a literature review. The results indicate that the generation in most of RADIC is less than the median of 0.521 kg day-1 per capita in China, and much smaller than in rural areas of developed countries (RADEC). Organic waste and inert waste with an accumulative mass percentage of 72.31% are dominant components of domestic waste in the rural areas of China. There are trends of increasing amounts of kitchen waste, paper/cardboard, and plastic/rubber and a decreasing trend of ash waste. The RADIC composition of domestic waste had a high content of organic waste and a low content of recyclable waste compared to the RADEC. Domestic waste has good compressibility and a light bulk density ranging from 40 to 650 kg m-3. The moisture, ash, combustible, and calorific values of domestic waste were 53.31%, 18.03%, 28.67%, and 5368 kJ kg-1, respectively. The domestic waste has an abundance of nutrients including organic matter (39.05%), nitrogen (1.02%), phosphorus (0.50%), and potassium (1.42%). In RADIC, domestic waste can be used as an agricultural manure only after it has been collected and sorted for the potential risk of heavy metal accumulation. Based on these characteristics of domestic waste and the different situations of rural areas, four waste management modes including centralized treatment, decentralized treatment, group treatment, and mobile treatment are designed and discussed.

Sorption of tetracycline on H3PO4 modified biochar derived from rice straw and swine manure.

Currently, the information about the sorption of tetracycline (TC) on animal manure derived biochar was rare although plant residue derived biochar showed high sorption of TC). Therefore, this study explored the sorption of TC on swine manure derived biochar, and compared with rice straw derived biochar simultaneously. Also, H3PO4 was adopted to modify both types of biochar. The sorption kinetic and isotherm data showed H3PO4 modification enhanced the sorption of TC on both types of biochar (especially swine-manure-biochar), and indicated the chemisorptions including H-bonding and π-π electron donor acceptor interaction might be the primary mechanism. Moreover, the strengthened electrostatic attraction between TC and biochars might largely explain the enhanced sorption capacity of TC along with pH increasing from 5.0 to 9.0. At the same conditions, swine manure derived biochar demonstrated lower sorption capacity of TC than rice straw biochar, but still could be good material for the sorption of TC.

Factors that influence public awareness of domestic waste characteristics and management in rural areas.

Public awareness of domestic waste characteristics and management (PADWCM) is a prerequisite for a domestic waste management (DWM) plan. In this study, we considered China as a typical example of developing countries to investigate the public perception of environmental pollution (PEP), its PADWCM, and its socioeconomic factors, using questionnaires and statistical methods. The results indicated that the public PEP was mainly due to obvious environmental contamination in local villages, and the PADWCM is still inadequate in rural areas. However, 83.9% of the respondents agreed that DWM is highly necessary. The PADWCM, including the hazard, recyclability, and characteristic pollution caused by domestic waste, was learned mainly from people's direct PEP, experiences, and repurchasing by recyclers. Education period had highly significant positive correlations and regressions with PEP and PADWCM, respectively. Additionally, education directly affected public awareness in different income and age groups. Demonstration projects had a significant positive effect on the awareness of characteristic pollution caused by domestic waste, which was readily perceived. Propaganda had a significant positive influence on the awareness of treatment necessity. Age and gender had no obvious effects on public PEP and PADWCM. Some aspects of PADWCM requiring a deep understanding became stronger as income increased; however, the PADWCM located close to poor people became weaker. Some aspects of PEP could significantly influence the awareness of characteristic pollution caused by domestic waste and awareness of treatment necessity. Therefore, improving environmental education, performing demonstration projects and effective environmental propaganda, increasing people's income, and attracting young people to participate in DWM will be important for enhancing environmental awareness and DWM in rural areas. Integr Environ Assess Manag 2018;14:395-406. © 2018 SETAC.

Influencing factors of domestic waste characteristics in rural areas of developing countries.

Waste management in rural areas has become a major challenge for governments of developing countries. The success of waste management decisions directly lies in the accuracy and reliability of the data on which choices are based; many factors influence these data. Here, we examined the factors influencing domestic waste in rural areas of developing countries (RADIC), using both field surveys and by reviewing previous literature. The social factors included population, education and culture. There was a positive linear relationship between waste generation amount and population size (R2 = 0.9405). Environmental education, training and demonstration projects played a positive role in improving people's awareness of the benefits of recycling and reducing waste. Traditional and national cultures, consumption and living habits contributed to variations in the generation and composition of domestic waste. Generally, practices related to conservation of and reverence for nature and green consumption encourage people to reduce, reuse and recycle waste in their daily life. Economic factors included household income and expenditure, energy and fuel structure, and types of industry that occurred in villages. A Kuznets inverted "U" curve relationship existed between domestic waste generation and people's income in rural areas of China. However, the waste generation rate had a linear relationship with the gross national income per capita in RADIC. The composition, bulk density and calorific value of domestic waste were variously affected by the energy and fuel structure and the types of industry that occurred. The natural factors included geography and climate (including rainfall, humidity, temperature and harvest seasons). The moisture content of waste was directly influenced by rainfall and humidity. Temperature affected waste characteristics by influencing residential heating modes. The waste characteristics were also influenced by the mixing of agricultural and aquacultural waste into domestic waste in the harvesting season. In different geographies, significant differences of domestic waste characteristics were observed as a result of comprehensive effects caused by multiple factors. Other factors included the administrative levels of communities and survey methods. The characteristics of domestic waste in towns or central villages were similar with those in cities, but were different from those in common villages (the smallest type of community). The domestic waste sampled in households indicated a lower rate of generation and lower ash content than when the waste was sampled at transfer stations or dumping sites. Based on the above analysis, the factors influencing domestic waste must be considered in order to optimize the design of waste management strategies in the RADIC. Furthermore, it is valuable and important to obtain more accurate data about waste characteristics.

Mechanism of adsorption of humic acid by modified aged refuse.

In the present study, aged refuse (AR) was modified to be applied as an adsorbent to remove humic acid from water. The efficiency of humic acid removal by modified aged refuse (MAR) under different preparation conditions (calcination temperature, dose of aged refuse for calcination and holding time) was systematically investigated. Results showed that the optimum preparation conditions are calcination temperature = 700 °C, AR dose for calcination = 25 g, and holding time = 2.0 h. The characteristics of the modified aged refuse obtained under different calcination conditions were determined by Fourier transform infrared, X-ray diffraction and X-ray photoelectron spectroscopy analysis. In addition, the effects of modified aged refuse dose and initial solution pH on adsorption performance were studied. The removal of humic acid increased with higher doses of modified aged refuse, and weak alkaline (initial pH = 8.0) conditions were favorable for humic acid removal. A pseudo-second order model fitted the experimental data well. Moreover, the adsorption isotherms were well described by the Langmuir isotherm model, in which the monolayer surface loading was calculated to be approximately 37 mg g-1. During the adsorption process, the molecular weight, degree of condensation and aromaticity of humic acid were considerably decreased, according to 3D-EEM analysis. MAR as a new type of adsorbent thus provides a potential adsorption method for humic acid.

A review of groundwater contamination near municipal solid waste landfill sites in China.

Landfills are the most widely used method for municipal solid waste (MSW) disposal method in China. However, these facilities have caused serious groundwater contamination due to the leakage of leachate. This study, analyzed 32 scientific papers, a field survey and an environmental assessment report related to groundwater contamination caused by landfills in China. The groundwater quality in the vicinity of landfills was assessed as "very bad" by a comprehensive score (FI) of 7.85 by the Grading Method in China. Variety of pollutants consisting of 96 groundwater pollutants, 3 organic matter indicators, 2 visual pollutants and 6 aggregative pollutants had been detected in the various studies. Twenty-two kinds of pollutants were considered to be dominant. According to the Kruskal-Wallis test and the median test, groundwater contamination differed significantly between regions in China, but there were no significant differences between dry season and wet season measurements, except for some pollutants in a few landfill sites. Generally, the groundwater contamination appeared in the initial landfill stage after five years and peaked some years afterward. In this stage, the Nemerow Index (PI) of groundwater increased exponentially as landfill age increased at some sites, but afterwards decreased exponentially with increasing age at others. After 25years, the groundwater contamination was very low at selected landfills. The PI values of landfills decreased exponentially as the pollutant migration distance increased. Therefore, the groundwater contamination mainly appeared within 1000m of a landfill and most of serious groundwater contamination occurred within 200m. The results not only indicate that the groundwater contamination near MSW landfills should be a concern, but also are valuable to remediate the groundwater contamination near MSW landfills and to prevent the MSW landfill from secondary pollutions, especially for developing countries considering the similar situation of MSW disposal.

Characteristics and management of domestic waste in a rural area of the Tibetan Plateau.

UNLABELLED: In the rural area of the Tibetan Plateau (RATP), the characteristics of domestic waste, people's environmental awareness, people's willingness to pay and their influence factors were firstly studied by questionnaires, field samplings and laboratory tests. The results showed that, in the RATP, the generation of domestic waste was 85 g•d-1 per capita and it was mainly composed of plastics, inert waste, kitchen waste, glass and paper. The waste bulk density, moisture content, ash, combustible and low calorific value were 65 kg•m-3, 19.25%, 44.90%, 35.85% and 10,520 kJ•kg-1 respectively. These characteristics are influenced by income sources and geographical position to some extent. Classified collection should be promoted widely on the household and the village basis. Compost, fermentation, landfill, bioreactor landfill and semi-aerobic landfill have been approved as effective techniques to treat domestic waste, except incineration. The distance of 50-800 m between each collection facility and the disposal fee of around $0.8 per month per household are suggested. For suburbs or large population villages, it's better to treat domestic waste by the centralized way. But for the remote rural areas, a decentralized way is proposed. Significantly, the educational and economic influence should be considered into an effective domestic waste management program. IMPLICATIONS: The current situatio n of the environment in the rural areas of the Tibetan Plateau (RATP) was surveyed. There, the generation of organics and moisture of domestic waste were low but ash, recyclables, and combustibles were high. People's knowledge of domestic waste was absent but their participation in management was strong. Based on the current situation, compost, fermentation, and landfill were effective but incineration was inappropriate. Also, a localized mini landfill for a cluster of villages and or settlements was the best method there.

Electrophysiologic effects of nicorandil on the guinea pig long QT1 syndrome model.

INTRODUCTION: The slow component of the delayed rectifier K+ current IKs modulates repolarization of the cardiac action potential (AP), and the loss of IKs is known to cause long QT1 (LQT1) syndrome by prolonging action potential duration (APD). In this study, we generated a guinea pig LQT1 syndrome model using the IKs blocker chromanol 293B and then assayed the electrophysiologic effects of the ATP-sensitive potassium channel IK,ATP opener nicorandil on this model. METHODS AND RESULTS: Transmembrane action potentials of perfused right ventricular papillary muscle preparations and both in vitro and in vivo ECGs of guinea pigs were recorded. Blockade of IKs by chromanol 293B (30 microM) prolonged the action potential duration at 90% repolarization (APD90) by 8.5% and QT interval by 16.5% of control values. In addition, proarrhythmic early afterdepolarizations (EADs) and ventricular fibrillation were observed. Venoinjection of chromanol 293B (1 mg/kg) revealed 10.9% QT prolongation. Nicorandil (5-30 microM) dose-dependently shortened APD90 under the control condition, whereas it reversed the AP prolongation effect of chromanol 293B by 7.4% at the 30 microM concentration. Moreover, nicorandil shortened QT intervals both in vitro and in vivo and displayed an inhibitory effect on EADs and ventricular fibrillation. CONCLUSION: The ATP-sensitive potassium channel opener nicorandil may be an effective drug in the therapy of LQT1 syndrome by shortening APD and the QT interval.