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Resultados 1 - 20 de 592
1.

Consumer Perceptions of the Safety of Ready-to-Eat Foods in Retail Food Store Settings.

J Food Prot; 80(8): 1364-1377, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28722484

Resumo

To better understand how consumers perceive food safety risks in retail food store settings, a survey was administered to 1,041 nationally representative participants who evaluated possible food safety risks depicted in selected photographs and self-reported their perceptions, attitudes, and behaviors. Participants were shown 12 photographs taken at retail stores portraying either commonly perceived or actual food safety contributing factors, such as cross-contamination, product and equipment temperatures, worker hygiene, and/or store sanitation practices. Participants were then asked to specifically identify what they saw, comment as to whether what they saw was safe or unsafe, and articulate what actions they would take in response to these situations. In addition to the survey, focus groups were employed to supplement survey findings with qualitative data. Survey respondents identified risk factors for six of nine actual contributing factor photographs >50% of the time: poor produce storage sanitation (86%, n = 899), cross-contamination during meat slicing (72%, n = 750), bare-hand contact of ready-to-eat food in the deli area (67%, n = 698), separation of raw and ready-to-eat food in the seafood case (63%, n = 660), cross-contamination from serving utensils in the deli case (62%, n = 644), and incorrect product storage temperature (51%, n = 528). On a scale of 1 to 5, where 1 was very unsafe and 5 was very safe, a significant difference was found between average risk perception scores for photographs of actual contributing factors (score of ca. 2.5) and scores for photographs of perceived contributing factors (score of ca. 2.0). Themes from the focus groups supported the results of the survey and provided additional insight into consumer food safety risk perceptions. The results of this study inform communication interventions for consumers and retail food safety professionals aimed at improving hazard identification.
2.

Piloting water quality testing coupled with a national socioeconomic survey in Yogyakarta province, Indonesia, towards tracking of Sustainable Development Goal 6.

Int J Hyg Environ Health; 2017 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-28743592

Resumo

There remains a pressing need for systematic water quality monitoring strategies to assess drinking water safety and to track progress towards the Sustainable Development Goals (SDG). This study incorporated water quality testing into an existing national socioeconomic survey in Yogyakarta province, Indonesia; the first such study in Indonesia in terms of SDG tracking. Multivariate regression analysis assessed the association between faecal and nitrate contamination and drinking water sources household drinking water adjusted for wealth, education level, type of water sources and type of sanitation facilities. The survey observed widespread faecal contamination in both sources for drinking water (89.2%, 95%CI: 86.9-91.5%; n=720) and household drinking water (67.1%, 95%CI: 64.1-70.1%; n=917) as measured by Escherichia coli. This was despite widespread improved drinking water source coverage (85.3%) and commonly self-reported boiling practices (82.2%). E.coli concentration levels in household drinking water were associated with wealth, education levels of a household head, and type of water source (i.e. vender water or local sources). Following the proposed SDG definition for Target 6.1 (water) and 6.2 (sanitation), the estimated proportion of households with access to safely managed drinking water and sanitation was 8.5% and 45.5%, respectively in the study areas, indicating substantial difference from improved drinking water (82.2%) and improved sanitation coverage (70.9%) as per the MDGs targets. The greatest contamination and risk factors were found in the poorest households indicating the urgent need for targeted and effective interventions here. There is suggested evidence that sub-surface leaching from on-site sanitation adversely impacts on drinking water sources, which underscores the need for further technical assistance in promoting latrine construction. Urgent action is still needed to strengthen systematic monitoring efforts towards tracking SDG Goal 6.
3.

Enabling the sustainable Faecal Sludge Management service delivery chain-A case study of dense settlements in Kigali, Rwanda.

Int J Hyg Environ Health; 220(6): 960-973, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28596087

Resumo

The lack of access to basic sanitation is a global concern and alarmingly prevalent in low- and middle- income countries. In the densely populated settlements of these countries, on-site sanitation systems are usually the only feasible option because dwellers there have no sewers in place to connect to. Using on-site sanitation facilities results in an accumulation of faecal sludge which needs to be properly managed to ensure the well-being of the users as well as the surrounding environment. Unfortunately, often the conditions for faecal sludge management (FSM) within dense settlements are adverse and thus hamper sustainable FSM. We use the normative framework of the FSM enabling environment to gather empirical evidence from densely populated settlements of Kigali city in Rwanda to examine current FSM practices and the extent to which these are being influenced and affected by the setting within which they are taking place. The analysis of the study findings confirms that the existing conditions for FSM in these settlements are inadequate. The specific constraints that hinder the achievement of sustainable FSM include limited government focus on the sanitation sector, high turnover of staff in relevant government institutions, pit sludge management is not placed on the sanitation projects agenda, the existing relevant bylaws are not pro-poor oriented, a lack of clear responsibilities, a lack of relevant local professional training opportunities, unaffordability of FSM services and an inhibition to discuss FSM. Drawing on the involved stakeholders' own perceptions and suggestions, we identify possible approaches to overcome the identified constraints and to allow all actors in the FSM chain to contribute effectively to the management of faecal sludge in densely populated low-income urban settlements. Finally, our study also presents a contribution to the theoretical conceptualisation of the enabling environment for sustainable FSM.
4.

Examining the safety of menstrual cups among rural primary school girls in western Kenya: observational studies nested in a randomised controlled feasibility study.

BMJ Open; 7(4): e015429, 2017 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-28473520

Resumo

OBJECTIVE: Examine the safety of menstrual cups against sanitary pads and usual practice in Kenyan schoolgirls. DESIGN: Observational studies nested in a cluster randomised controlled feasibility study. SETTING: 30 primary schools in a health and demographic surveillance system in rural western Kenya. PARTICIPANTS: Menstruating primary schoolgirls aged 14-16 years participating in a menstrual feasibility study. INTERVENTIONS: Insertable menstrual cup, monthly sanitary pads or 'usual practice' (controls). OUTCOME MEASURES: vaginal colonization, growth on sampled used cups, toxic shock syndrome or other adverse health outcomes. RESULTS: Among 604 eligible girls tested, no adverse event or TSS was detected over a median 10.9 months follow-up. prevalence was 10.8%, with no significant difference over intervention time or between groups. Of 65 positives at first test, 49 girls were retested and 10 (20.4%) remained positive. Of these, two (20%) sample isolates tested positive for toxic shock syndrome toxin-1; both girls were provided pads and were clinically healthy. Seven per cent of cups required replacements for loss, damage, dropping in a latrine or a poor fit. Of 30 used cups processed for growth, 13 (37.1%, 95% CI 21.1% to 53.1%) had growth. growth was greatest in newer compared with established users (53%vs22.2%, p=0.12). CONCLUSIONS: Among this feasibility sample, no evidence emerged to indicate menstrual cups are hazardous or cause health harms among rural Kenyan schoolgirls, but large-scale trials and post-marketing surveillance should continue to evaluate cup safety.
5.

Profiles and removal efficiency of polycyclic aromatic hydrocarbons by two different types of sewage treatment plants in Hong Kong.

J Environ Sci (China); 53: 196-206, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28372744

Resumo

Sewage discharge could be a major source of polycyclic aromatic hydrocarbons (PAHs) in the coastal waters. Stonecutters Island and Shatin Sewage Treatment Works (SCISTW and STSTW) in Hong Kong, adopted chemically enhanced primary treatment and biological treatment, respectively. This study aimed at (1) determining the removal efficiencies of PAHs, (2) comparing the capabilities in removing PAHs, and (3) characterizing the profile of each individual PAHs, in the two sewage treatment plants (STPs). Quantification of 16 PAHs was conducted by a Gas Chromatography. The concentrations of total PAHs decreased gradually along the treatment processes (from 301±255 and 307±217ng/L to 14.9±12.1 and 63.3±54.1ng/L in STSTW and SCISTW, respectively). It was noted that STSTW was more capable in removing total PAHs than SCISTW with average total removal efficiency 94.4%±4.12% vs. 79.2%±7.48% (p<0.05). The removal of PAHs was probably due to sorption in particular matter, confirmed by the higher distribution coefficient of individual and total PAHs in solid samples (dewatered sludge contained 92.5% and 74.7% of total PAHs in SCISTW and STSTW, respectively) than liquid samples (final effluent-total contained 7.53% and 25.3% of total PAHs in STSTW and SCISTW, respectively). Despite the impressive capability of STSTW and SCISTW in removing PAHs, there was still a considerable amount of total PAHs (1.85 and 39.3kg/year, respectively for the two STPs) being discharged into Hong Kong coastal waters, which would be an environmental concern.
6.

Associating liver partition and portal vein ligation for bleeding hepatocellular carcinoma in HBV cirrhosis: a safety strategy.

Artigo em Inglês | MEDLINE | ID: mdl-28447055

Resumo

The incidence of hepatocellular carcinoma (HCC) spontaneous tumor rupture varies between 3% and 26%. For resectable HCC ruptures, emergency hepatectomy or staged hepatectomy after transcatheter arterial embolization (TAE) are life-saving procedures, and efficient therapeutic methods. We report a multimodal therapy including TAE, associating liver partition and portal vein ligation (ALPPS) and immunoglobuline infusion for a huge bleeding HCC with portal vein tumor thrombosis (PVTT) in hepatitis B virus (HBV) cirrhosis. ALPPS first step began with an abdominal toilette due to the massive hemoperitoneum and a portal vein incision at the bifurcation of the right and left portal veins was performed. A freely floating left part of the thrombus was extracted from the left portal vein in order to restore the left portal vein. The right portal vein with complete thrombosis was closed. Liver partition was then performed. The second step was performed without complications. A HCC Edmondson grade 4 (pT3b) and a cirrhotic liver parenchyma were described. Postoperative ascites decompensation was treated and patient was discharged in postoperative day 21. The reported triple strategy allowed us to prolong patient live. A multimodal therapy including TAE, ALPPS and immunoglobuline is a good option for a life treatment in case of huge bleeding hepatocellular carcinoma with PVTT in HBV cirrhosis.
7.

Sewage sludge disposal strategies for sustainable development.

Environ Res; 156: 39-46, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28314153

Resumo

The main objective of the present review is to compare the existing sewage sludge management solutions in terms of their environmental sustainability. The most commonly used strategies, that include treatment and disposal has been favored within the present state-of-art, considering existing legislation (at European and national level), characterization, ecotoxicology, waste management and actual routs used currently in particular European countries. Selected decision making tools, namely End-of-waste criteria and Life Cycle Assessment has been proposed in order to appropriately assess the possible environmental, economic and technical evaluation of different systems. Therefore, some basic criteria for the best suitable option selection has been described, in the circular economy "from waste to resources" sense. The importance of sewage sludge as a valuable source of matter and energy has been appreciated, as well as a potential risk related to the application of those strategies.
8.

Towards sustainable sanitation management: Establishing the costs and willingness to pay for emptying and transporting sludge in rural districts with high rates of access to latrines.

PLoS One; 12(3): e0171735, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28323885

Resumo

MOTIVATION: Proper management of fecal sludge has significant positive health and environmental externalities. Most research on managing onsite sanitation so far either simulates the costs of, or the welfare effects from, managing sludge in situ in pit latrines. Thus, designing management strategies for onsite rural sanitation is challenging, because the actual costs of transporting sludge for treatment, and sources for financing these transport costs, are not well understood. METHODS: In this paper we calculate the actual cost of sludge management from onsite latrines, and identify the contributions that latrine owners are willing to make to finance the costs. A spreadsheet-based model is used to identify a cost-effective transport option, and to calculate the cost per household. Then a double-bound contingent valuation method is used to elicit from pit-latrine owners their willingness-to-pay to have sludge transported away. This methodology is employed for the case of a rural subdistrict in Bangladesh called Bhaluka, a unit of administration at which sludge management services are being piloted by the Government of Bangladesh. RESULTS: The typical sludge accumulation rate in Bhaluka is calculated at 0.11 liters/person/day and a typical latrine will need to be emptied approximately once every 3 to 4 years. The costs of emptying and transport are high; approximately USD 13 per emptying event (circa 14% of average monthly income); household contributions could cover around 47% of this cost. However, if costs were spread over time, the service would cost USD 4 per year per household, or USD 0.31 per month per household-comparable to current expenditures of rural households on telecommunications. CONCLUSION: This is one of few research papers that brings the costs of waste management together with financing of that cost, to provide evidence for an implementable solution. This framework can be used to identify cost effective sludge management options and private contributions towards that cost in other (context-specific) administrative areas where onsite sanitation is widespread.
9.

Evaluation of thermal hydrolysis efficiency of mechanically dewatered sewage sludge via rheological measurement.

Water Res; 116: 34-43, 2017 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-28292678

Resumo

In this study, laboratory tests of both low temperature (60-90 °C) and high temperature (120-180 °C) thermal hydrolysis (LTHP and HTHP) were performed on mechanically dewatered high-solid sludges (at total solid of 14.2 wt% and 18.2 wt%) to evaluate the extent of organic solubilization through rheological measurements. The effects of treatment temperature and duration on organic solubilization and viscoelastic behavior of the sludge were comprehensively investigated. The results indicated that the organic solubilization contents including soluble chemical oxygen demand, soluble protein, and soluble polysaccharides increased logarithmically with the treatment time. Protein solubilized considerably faster than polysaccharides during thermal hydrolysis. The rheological curves exhibited the Payne effect in the amplitude sweep oscillation test. The elastic modulus in linear viscoelastic regime decreased logarithmically with treatment time. The viscoelastic behavior of sludge was well modeled by the Kaye-Bernstein-Kearsly-Zapas (KBKZ) model with paralleled Maxwell elements to describe the frequency dependence of elastic modulus and viscous modulus. With respect to the relaxation spectrum, the relaxation modulus first decreased with relaxation time and then increased. The relaxation modulus in each Maxwell element decreased with the treatment temperature and duration. Furthermore, in the HTHP, the influence of treatment temperature on enhancing organic solubilization and decreasing viscoelasticity exceeded the influence of treatment duration. In contrast, the treatment duration played a more important role than temperature in the LTHP. The content of organic matters was linearly related and logarithmically related to the elastic modulus in the LTHP and in the HTHP, respectively. The rheology analyses demonstrated that viscoelastic properties could be used as indicators to estimate the extent of organic matter solubilization in thermal hydrolysis process. The developed viscoelastic model provided insights for future research in numerically simulating the fluid dynamics of sludge.
10.

Removal of hydrogen sulfide generated during anaerobic treatment of sulfate-laden wastewater using biochar: Evaluation of efficiency and mechanisms.

Bioresour Technol; 234: 115-121, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28319759

Resumo

Removal of hydrogen sulfide (H S) from biogas was investigated in a biochar column integrated with a bench-scale continuous-stirred tank reactor (CSTR) treating sulfate-laden wastewater. Synthetic wastewater containing sulfate concentrations of 200-2000mg SO /L was used as substrate, and the CSTR was operated at an organic loading rate of 1.5g chemical oxygen demand (COD)/L·day and a hydraulic retention time (HRT) of 20days. The biochar was able to remove about 98.0 (±1.2)% of H S for the ranges of concentrations from 105-1020ppmv, especially at high moisture content (80-85%). Very high H S adsorption capacity (up to 273.2±1.9mg H S/g) of biochar is expected to enhance the H S oxidation into S and sulfate. These findings bring a potentially novel application of sulfur-rich biochar as a source of sulfur, an essential but often deficient micro-nutrient in soils.
11.

Long-term stability and nutrient removal efficiency of aerobic granules at low organic loads.

Bioresour Technol; 234: 336-342, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28340438

Resumo

The feasibility of application of aerobic granular sludge cultivated with high organic loads for biological nutrient removal (BNR) from low-strength wastewater was studied. Granules obtained with high-strength (COD=1400mg/L) wastewater were fed with medium (COD=700mg/L) and then low-strength (COD=400mg/L) wastewater. The granules rapidly acclimated to the medium-strength wastewater. However, feeding with low-strength wastewater reduced the F/M ratio from 0.4 to 0.2gCOD/gVSSd and granules disintegration occurred. Re-granulation was obtained after poor settling biomass was washed out and the F/M ratio reached 0.4gCOD/gVSSd. Disintegration of granules coincided with the decrease in extracellular polymeric substances (EPS) content and protein-to-carbohydrate ratio and re-granulation was assisted with the increase in EPS and protein-to-carbohydrate ratio. The results indicated that cultivation of aerobic granules with high organic loads and its implication for BNR treatment of low-strength wastewater while balancing the F/M ratio can be an alternative to reduce start-up period.
12.

Multiple approaches to assess the safety of artisanal marine food in a tropical estuary.

Environ Monit Assess; 189(3): 125, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28238170

Resumo

In this study, metal and metalloid concentrations and pathogens were measured in shellfish at different locations in a tropical estuary, including sites impacted by sewage and industry. Oyster, mangrove snails and mud snails did not exceed Australian and New Zealand Food Standards maximum levels for copper, lead or estimated inorganic arsenic at any site although copper concentrations in oysters and mud snails exceeded generally expected levels at some locations. Bacterial community composition in shellfish was species-specific regardless of location and different to the surrounding water and sediment. In the snails Telescopium telescopium, Terebralia palustris and Nerita balteata, some bacterial taxa differed between sites, but not in Saccostrea cucullata oysters. The abundance of potential human pathogens was very low and pathogen abundance or diversity was not associated with site classification, i.e. sewage impact, industry impact and reference.
13.

Sustainable use of tannery sludge in brick manufacturing in Bangladesh.

Waste Manag; 60: 259-269, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28081994

Resumo

Chromium-rich tannery sludge generated from tanneries has the potential to become a serious environmental burden in Bangladesh and a promising avenue for disposal of this sludge is by stabilizing it in clay brick products. But for sustainable industrial application of such technique it needs to be ensured first that the engineering properties of bricks as a building material are not diminished by addition of sludge, the process becomes energy efficient compared to alternatives and the use of such bricks do not pose any harmful environmental effects in the long run. In this study, clay bricks were prepared with different proportions of sludge (10%, 20%, 30% and 40% by dry weight) in both laboratory-controlled and field conditions and their suitability as a construction material was assessed based on their strength, water absorption, shrinkage, weight-loss on ignition and bulk density. For the sludge incorporated bricks, the compressive strength ranged from 10.98MPa to 29.61MPa and water absorption ranged from 7.2% to 20.9%, which in most cases met both the Bangladesh and ASTM criteria for bricks as a construction material. Volumetric shrinkage, weight loss and efflorescence properties of sludge-amended bricks were found to be favorable and it was estimated that an energy saving of 15-47% could potentially be achieved during firing with 10-40% tannery sludge-amended bricks. The quality of sludge-amended bricks made in the brick kiln was relatively inferior compared to bricks produced in the laboratory due to operating in a less-controlled environment with respect to maintaining adequate compaction and optimum moisture content. The leaching behavior of several heavy metals (Cr, As, Cu, Ni, Cd, Pb and Zn) from sludge-amended bricks has been found to be insignificant and far below the Dutch regulations and USEPA regulatory limits. Results from this study indicate that tannery sludge can be sustainably stabilized in clay bricks and large-scale application of this technique can be envisaged in the context of Bangladesh where brick remains a dominant building material.
14.

Efficiency of sewage sludge biochar in improving urban soil properties and promoting grass growth.

Chemosphere; 173: 551-556, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28142113

Resumo

It is meaningful to quickly improve poor urban soil fertility in order to establish the green land vegetation. In this study, a series rates (0%, 1%, 5%, 10%, 20% and 50%, in mass ratio) of biochar derived from municipal sewage sludge was applied into an urban soil and then turf grass was grown in pots. The results showed that biochar amendment induced significant increases in soil total nitrogen, organic carbon, black carbon, and available phosphorus and potassium by more than 1.5, 1.9, 4.5, 5.6 and 0.4 times, respectively. Turf grass dry matter increased proportionally with increasing amount of added biochar (by an average of 74%), due to the improvement in plant mineral nutrition. Biochar amendment largely increased the total amounts of soil heavy metals. However, 43-97% of the heavy metals in the amended soil were concentrated in the residual fraction with low bioavailability. So the accumulation of heavy metals in turf grass aboveground biomass was highly reduced by the addition of biochar. These results indicated that sewage sludge biochar could be recommended in the poor urban raw soil as a soil conditioner at a rate of 50%. However, the environmental risk of heavy metal accumulation in soil amended with sewage sludge biochar should be carefully considered.
15.

Fertilisers production from ashes after sewage sludge combustion - A strategy towards sustainable development.

Environ Res; 154: 171-180, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28086102

Resumo

Sustainable development and circular economy rules force the global fertilizer industry to develop new phosphorous recovery methods from alternative sources. In this paper a phosphorus recovery technology from Polish industrial Sewage Sludge Ashes was investigated (PolFerAsh - Polish Fertilizers form Ash). A wet method with the use of mineral acid and neutralization was proposed. Detailed characteristic of SSA from largest mono-combustion plans were given and compared to raw materials used on the market. The technological factors associated with such materials were discussed. The composition of the extracts was compared to typical industrial phosphoric acid and standard values characterizing suspension fertilizers. The most favorable conditions for selective precipitation of phosphorus compounds were revealed. The fertilizers obtained also meet EU regulations in the case of the newly discussed Cd content. The process was scaled up and a flow mass diagram was defined.
16.

Food safety knowledge, attitudes and practices of institutional food-handlers in Ghana.

BMC Public Health; 17(1): 40, 2017 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-28061850

Resumo

BACKGROUND: In large scale cooking, food is handled by many individuals, thereby increasing the chances of food contamination due to improper handling. Deliberate or accidental contamination of food during large scale production might endanger the health of consumers, and have very expensive repercussions on a country. The purpose of this study was to evaluate the food safety knowledge, attitudes, and practices among institutional food- handlers in Ghana. METHODS: The study was conducted using a descriptive, cross-sectional survey of 29 institutions by conducting face to face interview and administration of questionnaire to two hundred and thirty-five (235) institutional food-handlers. The questionnaire was peer-reviewed and pilot tested in three institutions in the Upper East Region of Ghana, before the final version was distributed to food-handlers. The questionnaire was structured into five distinctive parts to collect information on (i) demographic characteristics, (ii) employees' work satisfaction, (iii) knowledge on food safety, (iv) attitudes towards food safety and (v) food hygiene practices. RESULTS: Majority of the food-handlers were between 41-50 years (39.1%). Female respondents were (76.6%). In our study, the food-handlers were knowledgeable about hygienic practices, cleaning and sanitation procedures. Almost all of the food-handlers were aware of the critical role of general sanitary practices in the work place, such as hand washing (98.7% correct answers), using gloves (77.9%), proper cleaning of the instruments/utensils (86.4%) and detergent use (72.8%). On disease transmission, the results indicates that 76.2% of the food- handlers did not know that Salmonella is a food borne pathogens and 70.6% did not know that hepatitis A is a food borne pathogen. However, 81.7% handlers agreed that typhoid fever is transmitted by food and 87.7% agreed that bloody diarrhea is transmitted by food. Logistic regression analysis testing four models showed statistically significant differences (p < 0.05), for models in which the explanatory variable was the level of education. CONCLUSIONS: In generally, the institutional food-handlers have satisfactory knowledge in food safety but this does not translate into strict hygienic practices during processing and handling food products.
17.

Three-step effluent chlorination increases disinfection efficiency and reduces DBP formation and toxicity.

Chemosphere; 168: 1302-1308, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27919529

Resumo

Chlorination is extensively applied for disinfecting sewage effluents, but it unintentionally generates disinfection byproducts (DBPs). Using seawater for toilet flushing introduces a high level of bromide into domestic sewage. Chlorination of sewage effluent rich in bromide causes the formation of brominated DBPs. The objectives of achieving a disinfection goal, reducing disinfectant consumption and operational costs, as well as diminishing adverse effects to aquatic organisms in receiving water body remain a challenge in sewage treatment. In this study, we have demonstrated that, with the same total chlorine dosage, a three-step chlorination (dosing chlorine by splitting it into three equal portions with a 5-min time interval for each portion) was significantly more efficient in disinfecting a primary saline sewage effluent than a one-step chlorination (dosing chlorine at one time). Compared to one-step chlorination, three-step chlorination enhanced the disinfection efficiency by up to 0.73-log reduction of Escherichia coli. The overall DBP formation resulting from one-step and three-step chlorination was quantified by total organic halogen measurement. Compared to one-step chlorination, the DBP formation in three-step chlorination was decreased by up to 23.4%. The comparative toxicity of one-step and three-step chlorination was evaluated in terms of the development of embryo-larva of a marine polychaete Platynereis dumerilii. The results revealed that the primary sewage effluent with three-step chlorination was less toxic than that with one-step chlorination, indicating that three-step chlorination could reduce the potential adverse effects of disinfected sewage effluents to aquatic organisms in the receiving marine water.
20.

Non-destructive soil amendment application techniques on heavy metal-contaminated grassland: Success and long-term immobilising efficiency.

J Environ Manage; 186(Pt 2): 167-174, 2017 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-27594691

Resumo

Extensive contamination of grassland with cadmium (Cd), lead (Pb) and zinc (Zn) is a typical problem close to Pb/Zn smelter sites. The entry of Cd or Pb into the food chain is very likely, as are toxicity effects of Zn in plants. Previous promising results from pot and field experiments showed the high potential of using amendments for immobilisation to reduce metal input into the food chain via crops grown on smelter-contaminated soils at Arnoldstein (Austria) (Friesl et al., 2006). The aim of this study was to find a practical solution for large-scale contaminations in hilly regions that avoids erosion. Field application of amendments without destroying the vegetation cover (grassland) involved two approaches: (a) slurrying (Slu) the amendments into cut gaps in the vegetation cover and (b) injecting (Inj) the amendments through the vegetation cover. Here, we investigate the immobilising and long-term efficiency of treatments [gravel sludge (2.5%) + red mud (0.5%) (GS + RM)]. Risk assessment was based on soil, plant and water samples taken over a period of 10 years. Ammonium-nitrate-extractable Cd was reduced up to 50%, Pb up to 90%, and Zn over 90%. Plant uptake into the grass mixture and narrow leaf plantain was significantly reduced for Cd, Pb, and Zn. Harvesting early in vegetation period can further reduce uptake and meet the threshold for fodder crops. The reduction of these elements in the seepage water in 24 samplings within these 10 years reached 40%, 45% and 50%, respectively. Immobilisation increased microbial biomass and decreased human bioaccessibility for Pb. Our investigation of the long-term efficiency of GS + RM in all treatments shows that the Slu and Inj amendment application techniques have promising potential as a realistic and practical method for extensively contaminated hilly land. Slurrying performed best. We conclude that grassland remediation methods involving tillage are counterproductive from the viewpoint of bioaccessibility and soil protection and therefore should be avoided.
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