Azo dye wastewater treatment is urgent necessary nowadays. Electrochemical technologies commonly enable more efficient degradation of recalcitrant organic contaminants than biological methods, but those rely greatly on the energy consumption. A novel process of biofilm coupled with electrolysis, i.e., bioelectrochemical system (BES), for methyl orange (MO) dye wastewater treatment was proposed and optimization of main influence factors was performed in this study. The results showed that BES had a positive effect on enhancement of color removal of MO wastewater and 81.9% of color removal efficiency was achieved at the optimum process parameters: applied voltage of 2.0 V, initial MO concentration of 20 mg/L, glucose loads of 0.5 g/L and pH of 8.0 when the hydraulic retention time (HRT) was maintained at 3 d, displaying an excellent color removal performance. Importantly, a wide range of effective pH, ranging from 6 to 9, was found, thus greatly favoring the practical application of BES described here. The absence of a peak at 463 nm showed that the azo bond of MO was almost completely cleaved after degradation in BES. From these results, the proposed method of biodegradation combined with electrochemical technique can be an effective technology for dye wastewater treatment and may hopefully be also applied for treatment of other recalcitrant compounds in water and wastewater.
Advanced automotive fleet repair facility wastewater treatment was investigated with Zero-Valent Iron/Hydrogen Peroxide (Air/ZVI/H2O2) process for different process parameters: ZVI and H2O2 doses, time, pH. The highest Chemical Oxygen Demand (COD) removal efficiency, 76%, was achieved for ZVI/H2O2 doses 4000/1900 mg/L, 120 min process time, pH 3.0. COD decreased from 933 to 227 mg/L. In optimal process conditions odor and color were also completely removed. COD removal efficiency was increasing with ZVI dose. Change pH value below and over 3.0 causes a rapid decrease in the treatment effectiveness. The Air/ZVI/H2O2 process kinetics can be described as d[COD]/dt = −a [COD]tm, where ‘t’ corresponds with time and ‘a’ and ‘m’ are constants that depend on the initial reagent concentrations. H2O2 influence on process effect was assessed. COD removal could be up to 40% (560 mg/L) for Air/ZVI process. The FeCl3 coagulation effect was also evaluated. The best coagulation results were obtained for 700 mg/L Fe3+ dose, that was slightly higher than dissolved Fe used in ZVI/H2O2 process. COD was decreased to 509 mg/L.
The paper presents results of research concerning operating of five small wastewater treatment plants working in two different technologies: hydrobotanical wastewater treatment plant and constructed wetland. Each object was designed for the treatment of domestic sewage after preliminary mechanical treatment in a septic tank. Hydrobotanical wastewater treatment plants and one of constructed wetland beds were built for treating sewage produced in educational institutions and resort. In the article attention is paid to possibility of exceeding the maximum allowable concentration of pollutants for three main indicators of pollution: BOD5, COD, and total suspension. The reduction of these indices is required by the Regulation of the Minister of Environment [14] for wastewater treatment plants with PE < 2000. In addition, the paper presents the effects of wastewater treatment to reduce biogens. The best quality of outflow was reached by outflows from constructed wetland treatment plants. None of the observed objects fulfilled the requirements in terms of allowable concentrations for total suspension. The most effective were objects operating in technology of “constructed wetland”.
Scaling and corrosion associated with the use of natural hard water in cooling towers during recirculation pose great problems from both economical and technical points of view, such as decreased system efficiency and increased frequency of chemical cleaning. Treated municipal wastewater (MWW) is a promising alternative to freshwater as power plant cooling system makeup water, especially in arid regions. In this work, hybrid systems of salt precipitation (SP), nanofiltration (NF) and reverse osmosis (RO) were investigated, as potential pretreatment processes for wastewater reuse as cooling water in the planned Jordan nuclear power plants. The As-Samra wastewater was used to calculate the potential of carbonate and sulfate scale formation. The results were compared to scale potentials from Palo Verde wastewater. Four cases were investigated; SP, NF, SP-RO and NF-RO. The SP pretreatment cases showed the highest monovalent to divalent ratio because of a high removal of Ca and Mg and addition of Na from the chemicals of the SP step. The NF pretreatment cases, showed the lowest calcium sulfate scale potential and this potential decreases with the % pretreatment. The scale amount increases very slightly with concentration times when the SP and NF product is desalinated by RO step.
The aim of the work was to determine the technological reliability of the selected pollution indicators removal BOD5, CODCr and total suspension from the sewage treatment plant working with the bioreactor Pomiltek Mann type. Wastewater treatment plant which is a subject of this study is located in Lesser Poland, in Siepraw commune. The analysis was per-formed using the Weibull method for basic indicators of impurities, BOD5, CODCr and total suspended solids. Physico-chemical analyses of raw and treated wastewater, were carried out in the period from 2003 to 2014 (11 years). The research period included measured values of pollutions indicators in 38 samples of raw and treated sewage. For each of pollution indicators descriptive statistic, percentage reduction (��) and treatment plant reliability factors (RF) were calculated. Aver-age reduction for BOD5 and TSS was on level equal 94%, only for COD the average reduction was lower and was on level 89%. The reliability values determined by Weibull method, were: 75% (BOD5), 90% (CODCr) and 89.5% (TSS). The relia-bility results have been lower than the presented by literature source, which means that work of wastewater treatment plant in Siepraw was not satisfied in 11 years of research.
The remarkable development of sanitation in Morocco has inevitably led to the production of sludge generated from wastewater treatment plants in increasing quantities. Consequently, the problem of sludge management becomes persistent and worrying.
The aim of this paper was to contribute to the study of sewage sludge management issue in Morocco by identifying the various constraints hampering the sustainable disposal and/or recovery of municipal sewage sludge and drawing up rec-ommendations for the decision-makers. Moreover, in the context of improving by learning from best practices and seeking common solutions regarding this problematic, benchmarking with other countries has been conducted as well.
To carry out this study, a methodological approach was defined based on bibliographic research, surveys, interviews and benchmarking.
The constraints hampering the sustainable management of sludge are numerous and complex, they have not been tech-nical and environmental but also a regulatory, institutional-organizational and economic-financial nature yet. Therefore, municipalities, government and academia ideally would be encouraged to participate in the decision-making process re-garding the management of sewage sludge. Technical solutions, when coupled with stakeholder participation, can lead to policy implementation with a higher chance of improving the present situation.
In the case of Morocco, when comparing with others sludge recovery and disposal routes, land application (reuse in ag-riculture, silviculture and rehabilitation of degraded soils) remains the most environmentally friendly option, as well as a sustainable and economically viable solution.
The paper presents preliminary results of investigations on a relationship between turbidity and other quality parameters in the SBR plant effluent. The laboratory tests demonstrated a high correlation between an effluent turbidity and a total suspended solids (TSS) concentration as well as between TSS and COD. Such a relationship would help to continuously monitor and control quality of a wastewater discharge using turbidity measurement.
The aim of this study was to assess the effects of two flocculants that are often used to overcome activated sludge bulking problems - aluminium chloride, AlCl3, and aluminium sulphate, Al2(SO4)3 - on Lecaneinermis (Rotifera, Monogononta) at three different temperatures: 8, 15 and 20°C. The mean EC50 value (effective concentration, mg dm-3) calculated for the 24 h mortality test was 0.012 mg Al3+dm-3. Next, the effects of low concentrations of the Al-salts on the population development from single individuals (parthenogenetic females) were tested in a 21-day experiment. At concentrations as low as EC4.8 and EC0.48, both Al-salts affected rotifer population negatively. However, temperature was the most pronounced factor that modified the toxicity of the Al-salts to the rotifers. On the 12th day of the experiment, there were significant interactions between temperature and the Al-salts, indicating that the chemicals were more toxic to the rotifers at 20°C than at lower temperatures. The weaker rotifers sensitivity to Al-salts (especially to AlCl3) in temperatures below 15°C, when the biggest problems associated with sludge bulking occurs,may means use both rotifers and chemicals reasonable and effective.
The aim of this study was to determine the impact of the temperature of wastewater in a biological reactor with activated sludge and the BOD5/N-NH4 ratio in the influent to the treatment plant on nitrification efficiency and the concentration of ammonium nitrogen in treated wastewater. Tests were carried out in a household wastewater treatment plant which collects and treats sewage from a school building and a teacher’s house. During the 3-year study, large fluctuations in the sewage temperature in bioreactor were noted which was closely related to the ambient temperature. There were also large fluctuations in the concentration of organic matter and the concentration of ammonium nitrogen in inflowing sewage. The influence of wastewater temperature in the bioreactor and the BOD5/N-NH4 ratio on the concentration of ammonium nitrogen in treated wastewater was determined using Pearson’s linear correlation. A statistical analysis showed that a 1°C decrease in the temperature of wastewater in the bioreactor increased the concentration of ammonium nitrogen in treated wastewater by 2.64 mgN-NH4·L-1. Moreover, it was found that nitrification depended on the ratio of BOD5 to the concentration of ammonium nitrogen in wastewater flowing into the bioreactor. An increase in the BOD5/N-NH4 ratio by 1 value led to a 5.41 mgN-NH4·L-1 decrease in the concentration of ammonium nitrogen.
This paper deals with wastewater treatment systems placed in motorway service areas (MSAs). In the years 2008-2009 eight of such facilities installed on the stretch of the A2 motorway between Poznań and Nowy Tomyśl were examined and analyzed. The system consists of a septic tank, a submerged aerated biofilter and an outflow filter. The volume of traffic on the highway was analyzed, the amount of water use was measured and peak factors were calculated. On this basis it was concluded that the inflows to the wastewater treatment systems in many cases exceeded the nominal design values.
Based on the analysis of effluent quality it was found that the effects of plant operation in large part did not meet the requirements. It was found that the bioreactor aeration system and the design of the suspension separator (outflow filter) should be modified. One of the solutions was to use the soil-reed bed for wastewater treatment. The treatment of wastewater from the MSAs is a task that must take into account the unusual character of these facilities and the atypical quality of the effluent.
This paper presents the use of multi-criteria analysis as a tool that helps choosing an adequate technology for a household wastewater treatment plant. In the process of selection the criteria of sustainable development were taken into account. Five municipal mechanical-biological treatment plants were chosen for the comparative multi-criteria analysis. Different treatment technologies, such as sand filter, activated sludge, trickling filter, a hybrid system - activated sludge/trickling filter and a hybrid constructed wetland system VF-HF type (vertical and horizontal fl ow) were taken into account. The plants’ capacities were 1 m3∙d-1 (PE=8) and they all meet the environmental regulations. Additionally, a solution with a drainage system was included into the analysis. On the basis of multi-criteria analysis it was found that the preferred wastewater treatment technologies, consistent with the principles of sustainable development, were a sand filter and a hybrid constructed wetland type VF-HF. A drainage system was chosen as the best solution due to the economic criteria, however, taking into consideration the primary (ecological) criterion, employment of such systems on a larger scale disagree with the principles of sustainable development. It was found that activated sludge is the least favourable technology. The analysis showed that this technology is not compatible with the principles of sustainable development, due to a lack of proper technological stability and low reliability.