Phytoremediation performance of floating treatment wetlands with pelletized mine water sludge for synthetic greywater treatment

Buckets containing floating reed ( ) simulated floating treatment wetlands (FTWs) and were used to improve the remediation performance of synthetic greywater (SGW). The aim of the study was to investigate the behaviour of FTWs for treatment of key contaminants within artificial greywater. Pelletized ochre based on acid mine water sludge was introduced to selected FTWs, because of its capability in sequestration phosphorus and other trace elements. The impact of the following four operational variables were tested in the experimental set-ups of the FTWs (four replicates each): pollutant strength (high- (HC) and low- (LC) concentrations), treatment time (2- or 7-days of hydraulic retention time (HRT)), presence or absence of macrophytes ( ) and cement-ochre pellets. The results showed that 5 - day biochemical oxygen demand (BOD) and chemical oxygen demands (COD) were significantly (  < 0.05) reduced in all wetlands. Nitrate-nitrogen (NO -N) concentrations were significantly (  < 0.05) higher, and those measurements for PO -P were significantly (p < 0.05) lower than the corresponding ones determined for the influent. The existence of ochre pellets with significantly (  < 0.05) decreased B, Cd, Cr, Cu, Mg, Ni and Zn concentrations, but increased Al, Ca, Fe and K concentrations in the effluent, with the exception of sodium (Na). The FTW performances can be improved by utilising ochre-cement pellets to increase the pH of greywater. The presence of acts as a buffer to neutralise the pH of SGW. Rhizomes and biofilms mitigate increases in turbidity, TSS and colour values. [Abstract copyright: © The Author(s) 2019.

Assessment of capsicum annuum L. grown in controlled and semi-controlled environments irrigated with greywater treated by floating wetland systems

Accumulation of trace elements, including heavy metals, were evaluated in soil and fruits of chilli plants (Capsicum annuum L.) grown under both laboratory-controlled and semi-controlled greenhouse location conditions. Chilli plant biomass growth in different development stages and fruit productivity were evaluated and compared with each other for the impact of growth boundary conditions and water quality effects. Treated synthetic greywaters by different operational design set-ups of floating treatment wetland systems were recycled for watering chillies in both locations. Effluents of each individual group of treatment set-up systems were labelled to feed sets of three replicates of chilli plants in both locations. Results revealed that the treated synthetic greywater (SGW) complied with thresholds for irrigation water, except for high concentrations (HC) of phosphates, total suspended soils, and some trace elements, such as cadmium. Chilli plants grew in both locations with different growth patterns in each development stage. First blooming and high counts of flowers were observed in the laboratory. Higher fruit production was noted for greenhouse plants: 2266 chilli fruits with a total weight of 16.824 kg with an expected market value of GBP 176.22 compared to 858 chilli fruits from the laboratory with a weight of 3.869 kg and an estimated price of GBP 17.61. However, trace element concentrations were detected in chilli fruits with the ranking order of occurrence as: Mg > Ca > Na > Fe > Zn > Al > Mn > Cu > Cd > Cr > Ni > B. The highest concentrations of accumulated Cd (3.82 mg/kg), Cu (0.56 mg/kg), and Na (0.56 mg/kg) were recorded in chilli fruits from the laboratory, while greater accumulations of Ca, Cd, Cu, Mn, and Ni with concentrations of 4.73, 1.30, 0.20, 0.21, and 0.24 mg/kg, respectively, were linked to fruits from the greenhouse. Trace elements in chilli plant soils followed the trend: Mg > Fe > Al > Cr > Mn > Cd > Cu > B. The accumulated concentrations in either chilli fruits or the soil were above the maximum permissible thresholds, indicating the need for water quality improvements

Predominant mechanisms for the removal of nickel metal ion from aqueous solution using cement kiln dust

The experimental methodology achieved in the present study signified that the adsorption and precipitation were mainly mechanisms occurred together in the removal of nickel from aqueous solutions by sorption using cement kiln dust (CKD) byproduct as sorbent. Finding the contribution of each mechanism in the removal process and derivation an analytical model for finding the portion of precipitation were the focal points of this work. Results proved that the pure precipitation was increased with the increase of CKD dosage and metal concentration where total removal (adsorption-precipitation) ranged from 45 to 100%. The SEM micrographs of the CKD sorbent before and after sorption process certified that there was a crystal precipitates on the surface of the CKD. Also, these graphs in combination with FT-IR tests proved that [Ni(OH2)n]+2 (n=4-6) species were bonded with CKD and insoluble hydroxide species may be precipitated onto the CaO surfaces by co-precipitation, while K-O, Si-O and Ca-O groups enhanced the adsorption mechanism

Wetlands for wastewater treatment and subsequent recycling of treated effluent : a review

Due to water scarcity challenges around the world, it is essential to think about non-conventional water resources to address the increased demand in clean freshwater. Environmental and public health problems may result from insufficient provision of sanitation and wastewater disposal facilities. Because of this, wastewater treatment and recycling methods will be vital to provide sufficient freshwater in the coming decades, since water resources are limited and more than 70% of water are consumed for irrigation purposes. Therefore, the application of treated wastewater for agricultural irrigation has much potential, especially when incorporating the reuse of nutrients like nitrogen and phosphorous, which are essential for plant production. Among the current treatment technologies applied in urban wastewater reuse for irrigation, wetlands were concluded to be the one of the most suitable ones in terms of pollutant removal and have advantages due to both low maintenance costs and required energy. Wetland behavior and efficiency concerning wastewater treatment is mainly linked to macrophyte composition, substrate, hydrology, surface loading rate, influent feeding mode, microorganism availability, and temperature. Constructed wetlands are very effective in removing organics and suspended solids, whereas the removal of nitrogen is relatively low, but could be improved by using a combination of various types of constructed wetlands meeting the irrigation reuse standards. The removal of phosphorus is usually low, unless special media with high sorption capacity are used. Pathogen removal from wetland effluent to meet irrigation reuse standards is a challenge unless supplementary lagoons or hybrid wetland systems are used

Mineral and biological contamination of soil and Capsicum annuumirrigated with recycled domestic wastewater

Due to water scarcity in many arid countries, there is considerable interest in recycling wastewaterstreams such as treated urban wastewater for irrigation in the agricultural sector. The aim of this study isto assess the contamination of soil and Capsicum annuum (grown in pots) irrigated by domestic wastew-aters treated by different wetland types between September 2013 and September 2014. The objectiveswere to assess (a) the suitability of the irrigation water for growth when using recycled wastewatercontaminated by trace minerals and pathogens, (b) the impact of differently treated wastewaters on soiland fruits as a function of the wetland type, and (c) the marketable yield of the harvest as a functionof mineral and biological contamination risk. Ortho-phosphate-phosphorus, ammonia–nitrogen, potas-sium and manganese concentrations in the irrigation water considerably exceeded the thresholds. Highcontamination levels by total coliforms, Salmonella spp. and Streptococcus spp. were detected. No mineralcontamination was observed in the soils due to irrigation with treated wastewater. Results showed thatslight to moderate zinc contamination was detected in some vegetables. Potassium accumulation in theyield showed the highest values followed by zinc. In contrast, the lowest mineral accumulation of theyield was observed for iron. No bacterial contamination was detected for fruits harvested from plantsirrigated by wetland outflow water. In contrast, fruits harvested from those plants irrigated by prelimi-nary treated wastewater showed high contamination by total coliforms, Streptococcus spp. and Salmonellaspp. especially for fruits, which were located close to the contaminated soil surface. However, findingsindicate that vegetables receiving wastewater treated with wetlands can be considered as safe comparedto those receiving only preliminary treated wastewater. High yields in terms of economic return wereassociated with tap water and an organic growth medium, and a wetland with a small aggregate size anda low contact time

Recycling of domestic wastewater treated by vertical-flow wetlands for irrigating chillies and sweet peppers

Due to water scarcity in many arid countries, there is considerable interest in recycling various wastewater streams such as treated urban wastewater for irrigation in the agricultural sector. The aim was therefore to assess if domestic wastewater treated by different wetlands can be successfully recycled to water commercially grown crops. The objectives were to assess variables and boundary conditions impacting on the growth of two different types of peppers fed by domestic wastewater pre-treated by diverse mature constructed treatment wetlands. The growth of both Sweet Pepper (California Wonder; cultivar of Capsicum annuum Linnaeus Grossum Group) and Chilli (De Cayenne; C. annuum (Linnaeus) Longum Group ‘De Cayenne’) fed with different treated and untreated wastewater types were assessed. A few plants suffered from either a shortage and/or excess of some nutrients and trace minerals. The overall growth development of Sweet Peppers was poor due to the high concentrations of nutrients and trace minerals. In contrast, Chilies did reasonably well, but the growth of foliage was excessive and the harvest was delayed. High yields were associated with tap water and an organic growth medium, and a wetland with a high aggregate size, leaving sufficient space for biomass. Low fruit numbers correlated well with inorganic growth media and irrigation water contaminated by hydrocarbons. Findings indicate that nutrient concentrations supplied to the Chillies by a combination of compost and treated waste water are usually too high to produce a good harvest. However, as the compost is depleted of nutrients after about eight months, the harvest increased for pots that received pre-treated wastewater. The project contributes to ecological sanitation understanding by closing the loop in the food and water chain. Findings will lead to a better understanding of the effects of different wetland treatment processes on the recycling potential of their outflow waters