Summary This paper proposes an improved moth flame optimization (IMFO) algorithm to effectively solve the optimal power flow (OPF) problems. The concept of moth flame optimization (MFO) is inspired from the movement of moth towards the moon direction. IMFO is mainly based on the concept of MFO with modifying the path of moths in new spirals around the flame. Standard IEEE 30‐bus, IEEE 57‐bus and IEEE 118‐bus test systems are used to validate and prove the efficiency and robustness of IMFO algorithm. The validation of the proposed algorithm is based on 15 case studies in terms of different single and multi‐objective functions: fuel cost minimization, gas emission reduction, active power loss minimization, voltage profile improvement, and voltage stability enhancement. The simulation results of the proposed algorithm are compared with those obtained by other well‐known optimization techniques. The obtained results demonstrate the capability and robustness of IMFO algorithm to solve OPF problems. The results reveal that IMFO algorithm is capable of finding precise and better OPF solutions compared with the other techniques. A comparison among the convergence characteristics of IMFO technique and the other techniques proves the prevalence of IMFO to attain the optimal power flow solution with fast convergence.

When sewage sludge is incorrectly applied, it may adversely impact agro-system productivity. Thus, this study addresses the reaction of Cucumis sativus L. (cucumber) to different amendment rates (0, 10, 20, 30, 40 and 50 g kg) of sewage sludge in a greenhouse pot experiment, in which the plant growth, heavy metal uptake and biomass were evaluated. A randomized complete block design with six treatments and six replications was used as the experimental design. The soil electrical conductivity, organic matter and Cr, Fe, Zn and Ni concentrations increased, but the soil pH decreased in response to the sewage sludge applications. As approved by the Council of European Communities, all of the heavy metal concentrations in the sewage sludge were less than the permitted limit for applying sewage sludge to land. Generally, applications of sewage sludge of up to 40 g kg resulted in a considerable increase in all of the morphometric parameters and biomass of cucumbers in contrast to plants grown on the control soil. Nevertheless, the cucumber shoot height; root length; number of leaves, internodes and fruits; leaf area; absolute growth rate and biomass decreased in response to 50 g kg of sewage sludge. All of the heavy metal concentrations (except the Cu, Zn and Ni in the roots, Mn in the fruits and Pb in the stems) in different cucumber tissues increased with increasing sewage sludge application rates. However, all of the heavy metal concentrations (except the Cr and Fe in the roots, Fe in the leaves and Cu in the fruits) were within the normal range and did not reach phytotoxic levels. A characteristic of these cucumbers was that all of the heavy metals had a bioaccumulation factor <1.0. All of the heavy metals (except Cd, Cu and Zn) had translocation factors that were <1.0. As a result, the sewage sludge used in this study could be considered for use as a fertilizer in cucumber production systems in Saudi Arabia and can also serve as a substitute method of sewage sludge disposal. Graphical Abstract The effects of different sewage sludge amendment rates on the heavy metal bioaccumulation, growth and biomass of cucumbers.

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Although several studies have examined the effect of sewage sludge (SS) application on various legume crops, there is insufficient information confirming the agronomic and environmental sustainability of SS usage in a broad bean cultivation systems.Therefore, a greenhouse experiment was completed to assess the soil heavy metal (HM) pools, growth, yield, and HM uptake of Faba sativa Bernh. (broad bean) grown in the agricultural soils supplemented with SS in comparison to control soils (nonamended). The experimental design was completely randomized with six replicates. The amendment with SS significantly elevated the organic matter (OM) content, soil salinity and Al, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn concentrations, although the soil pH decreased. As allowed by the Council of European Communities, the concentrations of the determined HMs were less than the accepted limit for SS used in agriculture. Generally, SS applications of up to 120 t/ha produced a considerable increase in the growth measurements and biomass of broad bean. However, the broad bean biomass, shoot height, number of branches, root length, absolute growth rate, number of leaves, and leaf area declined in reaction to a rate of 150 t/ha. The HM concentrations in various tissues of broad bean plants exposed to SS were significantly higher than those in the untreated plants. However, most HM concentrations were inside the permissible limits and did not overcome the maximum levels of phytotoxic. The broad bean was recognized by a bioaccumulation factor less than 1.0 for the majority of the HMs. The translocation factors for the determined HMs (excluding for Al, Co, and Pb in stems and leaves) were less than 1.0. Therefore, the SS utilized in this study could be used as a fertilizer for broad bean crops and could as well act as a replacement manner for SS elimination. K E Y W O R D Samendments, biosolids, growth parameters, soil quality, trace elements, Vicia bean

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Summary Unified power flow controller (UPFC) is utilized to regulate the bus voltage as well as the power flow through a power system. A solution of optimal power flow (OPF) problems with UPFC is a crucial and complex task due to the required modifications for considering the parameters of UPFC. This work proposes a simplified UPFC modeling into an OPF code in order to avoid the programming complexity. Moreover, the solution of an OPF problem with a UPFC model is obtained by a recent physical‐based optimization technique called lightning attachment procedure optimization (LAPO). Different objective functions including minimizing fuel cost and fuel cost with valve point effect (VPE), reduction of emission, improvement of voltage profile, and improving the voltage stability index are considered. The proposed algorithm is tested using the standard IEEE 30‐bus system. The results obtained by the proposed algorithm are compared with those obtained by other optimization techniques. However, the obtained results verify the applicability of the simplified UPFC model in OPF.

In this study, we present the response of spinach to different amendment rates of sewage sludge (0, 10, 20, 30, 40 and 50 g kg) in a greenhouse pot experiment, where plant growth, biomass and heavy metal uptake were measured. The results showed that sewage sludge application increased soil electric conductivity (EC), organic matter, chromium and zinc concentrations and decreased soil pH. All heavy metal concentrations of the sewage sludge were below the permissible limits for land application of sewage sludge recommended by the Council of the European Communities. Biomass and all growth parameters (except the shoot/root ratio) of spinach showed a positive response to sewage sludge applications up to 40 g kg compared to the control soil. Increasing the sewage sludge amendment rate caused an increase in all heavy metal concentrations (except lead) in spinach root and shoot. However, all heavy metal concentrations (except chromium and iron) were in the normal range and did not reach the phytotoxic levels. The spinach was characterized by a bioaccumulation factor <1.0 for all heavy metals. The translocation factor (TF) varied among the heavy metals as well as among the sewage sludge amendment rates. Spinach translocation mechanisms clearly restricted heavy metal transport to the edible parts (shoot) because the TFs for all heavy metals (except zinc) were <1.0. In conclusion, sewage sludge used in the present study can be considered for use as a fertilizer in spinach production systems in Saudi Arabia, and the results can serve as a management method for sewage sludge.

The current study aimed at evaluating the effects of different sewage sludge (SS) amendment rates as biofertilizers on growth of Corchorus olitorius plants and soil properties, with an emphasis on heavy metal (HM) allocation in plant parts and postharvest soil. Then, the soil was supplemented with various SS rates (0, 10, 20, 30, and 40 g kg −1). The effects of these SS amendment rates on different growth parameters of Corchorus olitorius and soil properties were investigated. The SS amendment rate of 20 g kg −1 triggered the highest growth rates of Corchorus plants. Micronutrient HMs, including Co, Cu, Mn, and Ni, increased in the shoots of plants grown in soils amended with 20 g kg −1 , but with levels sufficient for normal plant growth and below the phytotoxic limits. The sludge application significantly increased the content of organic matter in postharvest soil from 1.38 to 4.83% at the amendment rate of 20 g kg −1. Furthermore, our data showed that the quantities of the estimated HMs remaining in postharvest soils were below (Cu, Fe, Mn, Mo, Zn, and Pb) or within (Co, Ni, Cd, and Cr) the maximum permissible concentrations in agricultural soils at all of the SS amendment rates. Taken together, our findings suggest that soil application of SS can provide a sustainable safe practice for SS disposal and improve plant growth, while exerting no environmental threats provided there is no accumulation of HMs to toxic levels in shoots of the grown plants or in the amended soils.