*Article*

#### **Study of Temperature Fields and Heavy Metal Content in the Ash and Flue Gas Produced by the Combustion of Briquettes Coming from Paper and Cardboard Waste**

**Harouna Gado Ibrahim 1,\*, Salifou K. Ouiminga 2, Arsène Yonli 2, Oumar Sanogo 3, Tizane Daho 2 and Jean Koulidiati 2**


Received: 16 May 2018; Accepted: 12 July 2018; Published: 13 July 2018

**Abstract:** The present study focused on the combustion of four types of briquettes made from paper and cardboard waste produced in Ouagadougou (Burkina Faso). Rotary and tubular kilns were used to study the combustion. The combustion mean temperatures, nitrogen, phosphorus and potassium (NPK) content in the ash and heavy metals content in the ash and the flue gas were analyzed. The combustion steady phase mean temperatures ranged from 950 ◦C to 750 ◦C were obtained according to briquettes type. The temperature favored the transfer of the heavy metal in the flue gas comparatively to the ash mainly for Hg, Cd and Pb. The Pb, Hg and Mn content in flue gas and the ash are higher than their content in the parent wood used for paper production due to the additive during the manufacturing process. The results showed a high content of heavy metal in flue gas produced by combustion of briquette made with office paper and in the ash for the briquette made of corrugated cardboard. Furthermore, the low heavy metal contain in the ash allow their use for soil amendment. However, ash contained a low proportion of NPK (less than 2%) which does not allow their usage as fertilizer alone.

**Keywords:** briquettes; ash; nitrogen-phosphorus-potassium; heavy metals
