Impact of Reject of Dairy Wastewater into the Aquatic Environment: Case of the Bayo Dairy Company (Brazzaville-Congo)

The development of industrial activities is the source of the production of large quantities of wastewater. The last-mentioned are rejected in the environment often without any prior treatment and have serious short-term and sometimes long-term environmental consequences. The objective of this work is to assess the environmental impacts and to propose a process for treating wastewater of reject from Bayo dairy in Brazzaville-Congo. The samples were taken at four (4) stations before, during and after production of dairy products. Multivariate statistical analysis of the physicochemical data was carried out using Statistica 7.1 software. The results obtained show that the wastewater from the Bayo dairy has a basic pH which fluctuates between 8.32 and 9.17 with standard temperatures of reject. The salinity of the wastewater increases greatly during production, which shows rising mineralization. The contents of MES (49.78-181.80 mg/L), MO (40.23-72.64 mg O2/L), COD (51.08-98.91 mg O2/L), BOD5 (34.80-59.50 mg O2/L) and the turbidity (26-179) NTU are moderately high and reflect an increase pollutant load before, during and after production of dairy products in stations S2 and S3. The COD/BOD5 ratio reveals that the Bayo dairy wastewater is moderately biodegradable before, during and after production with a biodegradability coefficient which varies between 1.40 and 1.78. The ACP approves possible industrial pollution from wastewater from the Bayo dairy and reports on the impact of the rejects in the environment. Thus, this study is a contribution to raising awareness among the Congolese population and decision-makers on the quality of wastewater rejected by local industries.