*2.1. Study Area*

The study area is located in Kaduna state (Lat. 10.52◦ N and Lat. 12◦ N, Long. 7.44◦ E and Long. 9◦ E). Kaduna state is located in the northern guinea savannah zone of Nigeria as one of the most developed industrial cities (Figure 1). The textile industry, flour mill, fertilizer, plastic, agrochemical, brewery, and bottling companies are some of the major industries sited in Kaduna state. The climatic conditions like most of Nigeria are characterized by the dry and wet season. The wet season commences either in April or May and ends in October of the same year while the dry season begins towards the end of October and ends in March the following year. Annual rainfall on average is between 1450 to 2000 mm with a temperature regime average of 25 to 43 ◦C, and relative humidity estimated to be between 20 and 40% in January and 60 to 80% in July. The solar radiation of the Kaduna state was 25.0 Wm−<sup>2</sup> day−<sup>1</sup> [24].

The River Kaduna is one of the major rivers in Nigeria. It stretches southwest and south course before completing a flow of 550 KM into River Niger. During its course through Kaduna city, it stretches along the southern part of the state through Kakuri where it receives industrial and domestic wastewater. It serves as a source of domestic water supply and irrigation farming for Kaduna urban settlements and its various industries [25].
