Reuse of pretreated cheese whey wastewater for industrial tomatoproduction (Lycopersicon esculentum Mill.)

Abstract

Due to the high organic load, suspended solids presence, fats content, salinity, etc., cheese whey wastewa-ter (CWW) disposal/management represents a complex issue from an environmental and engineeringpoint of view. In this work, an alternative wastewater management option is suggested. The processincludes the CWW pretreatment by means of a basic precipitation stage followed by neutralization of thesupernatant. This pre-stage is capable of reducing the organic, suspended solids and fats content to differ-ent levels. In a second step, the pretreated CWW has been used in the irrigation of tomato crops (cv. Romaand cv. Rio Grande). Different salinity levels corresponding to 1.75, 2.22, 3.22, 5.02 and 10.02 dS m−1havebeen tested. Taking into account the obtained results in control runs (fresh water), the salinity level ofthe pretreated CWW had no significant effect on the flower clusters number per plant, tomatoes numberper plant, tomatoes number per cluster, longitudinal and transversal calipers and epidermis firmness ofthe fruits. Moreover, an increment of soluble solid content in fruits (16% for cv. Roma and 27% for cv. RioGrande) was observed in saline treatments. Among the drawbacks experienced after irrigation with highsalinity level were some physiological disorders such as blossom-end rot. In this line, epidermis firmnessand caliper reductions were observed compared to marketable fruit although cv. Rio Grande was lesssensible to the aforementioned disorder. The effects of irrigation with pretreated CWW on the soil prop-erties were also investigated. As expected, soil conductivity linearly increased with the pretreated CWWsalinity level. Additionally, soil contents in phosphorus, nitrogen and organic matter were increased afterthe pretreated CWW irrigation. Under controlled saline conditions, the tomato plants irrigation can be asolution for by-products management from cheese industry with the fruits characteristics improvementand the wastewater inadequate discharge reduction.