Physico-Chemical Characterization of Local Tannery Waste Water Before and After Flocculation Treatment

Abstract

This paper presents the variation in physico-chemical properties of a local Maroua tannery effluent before and after a flocculation treatment. Tanning is a process that consists of the transformation of the animal skin into leather by using different baths which contain many chemical reagents and produces high quantity of liquid and solid waste. The used water of traditional tannery of Maroua is directly thrown in nature without any pre-treatment posing a potential risk to the environment and human health. Physico-chemical parameters such as temperature, pH and conductivity, Total suspended solids, Total hardness, chlorides, sulfides, nitrates,COD, BOD5 , ammonium ion, dissolve oxygen, turbidity, colour and odour were determined before and after aluminum sulfate powder flocculation treatment for effluents collected from soaking, liming, deliming and vegetable tanning stages of the tannery process. The results obtained showed that most of the physico-chemical parameters are higher than the international standard. The results obtained made it possible to classify these four effluents in order of toxicity as follows: Liming water > vegetable tanning water > deliming water > soaking water. The treatment of these waste waters by flocculation reduces the concentrations of certain pollutant loads such as TSS, turbidity, hardness, COD, BOD5, sulfate; but remains less effective on others such as nitrate, chloride and ammonium ion (8%). There is also a decrease in pH, an increase in dissolved oxygen and conductivity. The flocculation treatment thus considerably reduced the toxicity of these effluents, especially its organic load.

Artisanal tannery wastewater: quantity and characteristics

“…The black dye liquor (5.75) and the vegetable tanning wastewater (6.01) are slightly acidic due to the presence of the tannic acids emanating from the acacia pods ( Mahdi et al., 2006 ). Paltahe et al. (2019) reported pH values of 12.70, 9.10 and 7.10 for liming, deliming/bating liquors and vegetable tanning wastewater respectively which are in agreement with that obtained in this study.…”

“…The organic matter in the liquors stemmed from the use of plant materials (acacia pods, sorghum leaf sheath, pawpaw leaves), oils, as well as the hair, wool, flesh and adipose tissues which detached from the animal skins. Reported values in literature are 7100mgBOD 5 /L and 18330mgCOD/L for liming liquor; 3119mgBOD 5 /L and 8560mgCOD/L for deliming/bating liquor and 3042mgBOD 5 /L and 7640mgCOD/L for vegetable tanning wastewater ( Paltahe et al., 2019 ). Even though these are results from an artisanal tannery in Cameroun they differ from that obtained in this study possibly due to the variation in the number of skins processed and the quantities of plant materials or chemicals used in the preparation of the liquors as there are no strict measurement guiding the preparation of the liquors.…”

“…Information regarding water consumption, wastewater generation volumes and its characteristics are required for the design and management of these treatment schemes and also for the environmental impact assessment of indiscriminate discharge of tannery wastewater. Whilst this information is readily available for industrial tanneries ( Sawalha et al., 2019 ; Ilou et al., 2014 ; Islam et al., 2014 ), there is a paucity of it on artisanal tanneries, even though artisanal leather making remains a source of livelihood for lots of people in Ghana and in some other developing countries such as Ethiopia ( Gebremichael, 2016 ), Cameroun ( Paltahe et al., 2019 ), Sudan ( Skinner, 2007 ) and Nigeria ( Zaruwa and Kwaghe, 2014 ). From an extensive literature search, a study conducted by Paltahe et al.…”

“…Whilst this information is readily available for industrial tanneries ( Sawalha et al., 2019 ; Ilou et al., 2014 ; Islam et al., 2014 ), there is a paucity of it on artisanal tanneries, even though artisanal leather making remains a source of livelihood for lots of people in Ghana and in some other developing countries such as Ethiopia ( Gebremichael, 2016 ), Cameroun ( Paltahe et al., 2019 ), Sudan ( Skinner, 2007 ) and Nigeria ( Zaruwa and Kwaghe, 2014 ). From an extensive literature search, a study conducted by Paltahe et al. (2019) was the only work done investigating into the characteristics of artisanal tannery wastewater.…”

Optimization of Coagulation-flocculation Process for Pre-treatment of Artisanal Tannery Wastewater Using Response Surface Methodology

“…Although, it is estimated that 90% of tanneries world-wide engage in modern-day leather production practices (Dargo & Ayalew 2014), artisanal leather making is still an important source of livelihood for many people in most developing countries including Ghana (Wemegah 2014), Cameroon (Paltahe et al 2019), Ethiopia (Gebremichael 2016), Nigeria (Zaruwa & Kwaghe 2014) and Sudan (Skinner 2007). Wastewater emanating from these artisanal tanneries is usually discarded into the environment without treatment.…”