Myla R. A. dos Santos, et. al. International Journal of Engineering Research and Applications www.ijera.com ISSN: 2248-9622, Vol. 10, Issue 6, (Series-III) June 2020, pp. 47-52 www.ijera.com DOI: 10.9790/9622-1006034752 47 | Page Lettuce (Lactuva sativa L.) Irrigated with Domestic Sewage Treated in Protected Environment Myla R. A. dos Santos 1 , Raimundo R. Gomes Filho 1 *, Gregório G. Faccioli 1 , Clayton M. de Carvalho 2 , Tatiana P. Nunes 1 , Leonaria L. S. de Carvalho 3 , Renisson N. de Araújo Filho 4 , Alceu Pedrotti 1 , Manoel Valnir Júnior 5 , Sílvio C. R. V. Lima 6 1 Universidade Federal de Sergipe, São Cristovão, Sergipe, Brasil. 2 Instituto Federal de Educação, Ciência e Tecnologia Baiano, Serrinha, Bahia, Brasil. 3 Unversidade Federal do Ceará, Fortaleza, Ceará, Brasil. 4 Unversidade Federal de Tocantins, Gurupi, Tocantins, Brasil. 5 Instituto Federal de Educação, Ciência e Tecnologia do Ceará, Sobral, Ceará, Brasil. 6 Instituto Inovagri, Fortaleza, Ceará, Brasil. *Corresponding author: Raimundo R. Gomes Filho ABSTRACT The reuse of wastewater has been a strategy for the scarcity of water resources in arid and semiarid regions and to reduce the impact of this waste in water courses. In view of this, the aim of this work was to evaluate the development and production of “Baba de Verão” Lettuce (Lactuca sativa L.) in two cycles submitted to different concentrations of domestic sewage treated (0, 50 and 100%) and three irrigation depths, corresponding to 75, 100 and 125% of the soil moisture in the field capacity in protected environment. The concentrations of domestic sewage treated were prepared using water from the city's supply company and the sewage from the Sewage Treatment Station. The research was conceived in a randomized block design, generating a 3 x 3 factorial, with 5 repetitions. Utisol was used in the 45 pots used to grow the lettuce. It was used a critical tension of -30 kPa to determine the soil moisture critical and apply irrigation depth. The characteristics of leaf number, plant height, fresh weight and dry weight of lettuce were analyzed. Influences of the concentration of domestic sewage and the irrigation depth applied were observed separately, while the interaction did not influence the variables studied in the two crop cycles. The greater irrigation depths and the higher concentrations of domestic sewage provided greater development in the crop. Keywords: field capacity, tensiometry, wastewater --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 21-05-2020 Date of Acceptance: 07-06-2020 --------------------------------------------------------------------------------------------------------------------------------------- I. INTRODUCTION Brazil has a vast water reserve, but arid and semi-arid regions may suffer from water scarcity during droughts and the use of wastewater has been an alternative, arousing great interest and showing significant research advances in recent years [1]. The use of sewage effluent treated is not a new practice, however, there is a growing interest in the need to reuse it, especially in agriculture [2]. Many recent works have been carried out with the use of sewage effluent treated in the irrigation of several crops, among them radish [3], banana [4], okra [5], lettuce [6] and [7] and pepper [8] and [9]. The use of wastewater has become an interesting option as it reduces contamination by direct discharge of sewage into water bodies, allows more rational use of resources and is an alternative source of water available for agricultural crops [10]. Lettuce is one of the most significant leafy vegetables planted worldwide and consumed throughout the year [11]. Due to its short growing cycle, lettuce is a very nutrient demanding crop, and deficiency of these nutrients has symptoms that can be visually identified as abnormal colour, growth, burning and distortion of plant parts [12]. Thus, in addition to acting as a source of water, domestic sewage treated has the properties of a biofertilizer that can provide mineral nutrition to the crop [13]. The yield of vegetables in protected environment has increased significantly in recent decades. In addition, increase vegetable production has less environmental impact compared to field cultivation [11]. RESEARCH ARTICLE OPEN ACCESS